How to Build a Solar Hot Water System
By
John Canivan
Printing January, 2004
Sunny Future Press, Wantagh, NY
Copyright © John Canivan 2002
ISBN 0-9754980-0-2
All rights reserved. No part of this book may be reproduced or transmitted
in any form or by any means electronic or mechanical without the express
permission of the publisher. On line support is available from www.JCSolarHomes.com. If you have any questions or comments about this book
feel free to publish them on the JC Solar Collector Forum or join the Solar
Energy group or send email to [email protected].
How to Build a Solar Hot Water System is dedicated to:
My devoted wife, who lovingly tolerates the chaos I create, and…
Monday, a very special cat, who is now sleeping.
I
f you have $2000 and a few weeks of labor to invest this book can easily save
$50,000 or more in hot water. You folks with carpentry and plumbing skills have a
definite advantage. This book is also for anyone with a grasp of the English
language willing to learn carpentry and plumbing skills. A good solar heating
system is not free. It seems like it should be; after all heat from the sun is free why
isn’t the solar heating system? Fossil fuel contractors throw in oil burners for free
when they sign you sign up for a five-year contract. Why doesn’t Mr. Sunshine
give us the same deal? I guess Mr. Sunshine is just a mean old man.
We are all part of a vast, interdependent universe. Energy for life is our birthright
like the air we breathe or the water we drink. Our sun has enough energy to sustain
us, and still we burn the fluid remains of our ancestors to stay warm. Buckminster
Fuller, who coined the saying “Doing more with less,” compared fossil fuel with
the starter motor of an automobile. He believed that the modern technological
world we live in was started with a little boost from fossil fuel consumption. Once
started technology should free us from dependence on non-renewable energy. Our
starter motors are growing weary. It’s time to start the motor of social harmony,
get back to our roots and welcome in the “Solar Age”.
SOLAR ELECTRICITY:
The photovoltaic power industry has a long way to go
before becoming a practical investment for the average consumer although some
remote locations miles from the power grid find that it’s more practical to install
solar panels than have power lines run to their house. Government incentives and
technological production breakthroughs are necessary before the photovoltaic
industry blossoms. $5.00/watt is still too much for me. When the price comes
down to $1.00/ watt give me a call. A typical $40,000 residential investment would
take about 40 years to reach payback. This is of course assuming that $40,000 has
the same value today as it would have forty years from now. Solar Electricity is a
beautiful thing, but for most of us the time is not right. We’ll have to wait a little
longer until this growing technology becomes feasible.
SOLAR HEATING
Solar heating is feasible today. The average American
household consumes between 1000 and 2000 gallons of number two fuel oil per
year. Efficient use of the sun’s energy could easily cut this consumption in half or
eliminate it entirely. The heating of water is perhaps the easiest, most cost effective
solar project a person can get involved with.
1
TOOLS AND MATERIALS
TOOLS:
You will need a hammer, a table saw, a miter box or a miter saw, a
drill, drywall bits, (1/8, ¼, ¾) drill bits, a 3/8 inch drill, a soldering torch and other
soldering tools, tin snips, a hacksaw, and a paint brushes.
MATERIALS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
for collectors
Two rolls of 50-foot 20” aluminum flashing
Four .060-inch thick 4X8 sheets of Kalwall Sun-Lite Glazing from:
www.solar-components.com .
Twenty 1X4X8 pine with few or no knots
Four 3/8x4x8 CDX plywood
Four 1x4x8 sheets of isocynate insulation with foil backing
Sheet metal screws #10x1
One gallon of roofing tar
One gallon of oil base paint
Angle iron for mounting
Sixteen ¼ X 3 lag bolts, sixteen ¼ X 1½ inch machine bolts with nuts
and washers
1 ¼ inch and 2 inch drywall screws
One pound of 1½ inch galvanized nails with small heads
PLUMBING SUPPLIES
a. Eight 3/8 to ½ adaptors
b. Four ½ inch T’s
c. Two ½ X ½ X ¾ T’s
d. One ¾ inch T
e. Four ½ inch unions
f. Eight ½ inch elbows
g. One ¾ inch street elbow
h. One ¾ sweat to ¾ female pipe
i. One pressure relief valve
j. Four sixty foot rolls of 3/8 ID copper tubing
k. ½ - inch rigid copper tubing type L
l. 3/8-inch flexible copper tubing 4(60’ rolls)
m. ¾-inch flexible copper tubing 8(60’ rolls) DEPENDING
n. ¾ - inch rigid copper tubing type L or M
o. Solder and flux
2
How to Build a Solar Hot Water System
Chapter I
SOLAR HOT WATER SYSTEMS
Theory
Passive hot water
Active hot water
Heat transfer
Flow rate dynamics
Parallel flow
Serpentine flow
Application
Side joined collectors
Top/bottom joined collectors
Chapter II ABSORBER PLATE CONSTRUCTION
Theory
Materials
Pounding jig construction instructions
Absorber plate construction instructions
9
10
11
13
14
15-16
17-18
20
21
22
23-27
Chapter III COLLECTOR BUILDING INSTRUCTIONS
Step 1. Cut framing boards
28
Step 2. Assemble frame
29
Step 3. Fasten collector bottom and sides
30
Step 4. Construct tube bending jig
31
Step 5. Bend copper tubing
32
Step 6. Install insulation
33
Step 7. Drill inlet, outlet and vent holes
34
Step 8. Install absorber plate
35
Step 9. Install serpentine tubing
35
Step 10. Install sweat union
38
Step 11. Cut serpentine tube supports
40
Step 12. Install tube supports
41
Step 13. Paint absorber plate
42
Step 14. Install Kalwall
42
3
Chapter IV COLLECTOR MOUNTING
Theory of orientation and pitch
Assembly of horizontal and vertical supports
44
45
Chapter V HOT WATER STORAGE
Thermodynamic theory
Multi tank theory
Heat exchange coil theory
46
48
49
Chapter VI HEAT STORAGE VAULT CONSTRUCTION
Step 1. Tank preparation
51
Step 2. 4X4 supports
51
Step 3. Bottom platform
51
Step 4. Placing tanks on platform
52
Step 5. Framing the storage vault
53
Step 6. Insulating the storage vault
54
Step 7. Installing sides
54
Step 8. Installing sheet insulation
55
Step 9. Making and installing the inner lid
55
Chapter VII HEAT EXCHANGE COILS
Theory
Assembly
Inner lid construction and installation
56-60
61
63-65
Chapter VIII CIRCULATOR AND VAULT PLUMBING
Mounting platform
66
Plumbing overview
67
Details of plumbing
68
Assembly
69
Chapter IX COLLECTOR PLUMBING
Overview
Union T assembly
Main output junction assembly
4
70
71
72
Main input junction assembly
73
Chapter X
THE SENSOR SYSTEM
74
Chapter XI
FILLING AND DRAINING THE SYSTEM
75-76
Chapter XII OTHER SOLAR APPLICATIONS
77
GLOSSARY
78-79
Author’s Note
80
5
I
SOLAR HOT WATER SYSTEMS
What once was a luxury is now a necessity. Billions of households have or would
like to have running hot water.
In 1970 a friend of mine left the civilized comforts of a New Jersey home to seek
out and experience the free, wild wilderness of an Adirondack hilltop in upstate
New York. Jack loved the country life and swore that he’d never leave his
mountain retreat. He endured the cold winters without electricity and baseboard
heating, but Jack still missed running hot water. When spring came he took a 300foot coil of black plastic tubing and connected one end to a spring high up on the
mountain. He draped the remainder of the 300-foot coil on his roof and spread it
out to cover as much surface area as possible. For a $50 investment and one hour’s
worth of labor Jack had himself a bona fide hot water shower. He made good use
of it whenever the sun was high on the mountain. I used it a few times myself. It
works. The roof might look a little funny and the hot water would sometimes run
out sooner than you’d like, but it did work when the sun was shining.
When the sun disappeared the shower would get very cold. By the end of
September water would freeze inside the exposed plastic tubing.
You might be interested in a simple system like this if you enjoy taking showers
when the sun shines. If you’re looking for a more sophisticated hot water system
you’ll need to invest more time and more money.
This book briefly examines the possibilities of various hot water systems. If you
live in a warm sunny area a simple passive batch heater is probably all you’ll
need. If you’re interested in an automatic system that works well in cold climates
with a minimum amount of sunlight you’ll need an active array of flat plate
collectors along with a heat storage system. Parabolic-trough heat concentrating
collectors are best suited for large scale power generation so they will not be
explored for their domestic hot water application in this book.
6
The construction of a cost effective solar hot water system from commonly
available construction and plumbing supplies is the main concern of this book. The
only materials requiring a special order will be the Kalwall glazing and a
differential sensor relay system.
For collector glazing you could use low iron glass, but it’s expensive, fragile
and heavy. Thermo pane low iron glass is the best, but it’s also the most
expensive. A four by eight sheet of thermo pane is much heavier than a 4x8 sheet
of Kalwall. I recommend that you stick with the Kalwall. It’s tough, light, resistant
to UV degradation and easy to work with.
For a storage vault I am suggesting that you use a series of tanks through which
heat exchange coils are immersed. Fifty-five gallon drums make good storage
tanks, but they must be waterproofed to prevent rust. Some people that I’ve
corresponded with have used plastic drums. I guess that’s one way of eliminating
the rust problem. If you have difficulty obtaining and rust proofing 55-gallon
drums you could purchase standard water tanks new from a plumbing supply house
or you could purchase used tanks from a metal salvage yard. You might even pick
up a few used hot water tanks free around your neighborhood. People who convert
from gas heat to oil heat no longer need their perfectly good gas hot water tanks.
Keep your eyes out for discarded water tanks. Recycling is good for everyone and
you can’t beat the price.
External heat exchange works great with these kinds of tanks. All you need
to do is wrap the lower area of the tanks with soft copper tubing, bind it tightly to
the tank with bailing wire and chicken wire and then plaster the mesh to the tank
with cement. Cement is an excellent conductor of heat. One inch of stuccoed
cement should be sufficient. Just don’t forget to wrap your tanks in insulation
when you’re done. If you decide to go with external heat exchange be sure to get in
touch with me, and I’ll walk you through the process.
I’m sure you’ll come up with your own ingenious methods of gathering and storing
heat from the sun. The concepts and methods of construction explored in this book
should be used as guidelines for your special project. Feel free to exchange your
ideas and concerns with me. You can also post on the SOLAR HOT WATER
FORUM accessed from my home page at www.jc-solarhomes.com .
And now let’s take a quick look at some popular solar hot water systems.
7
PASSIVE HOT WATER
BATCH HEATERS
In mild climates like
coastal California or almost any place in Florida
where freezing is a rare occurrence a
simple passive batch heating system is all
that’s necessary. The batch heater could
be as simple as a water tank painted
black. A more efficient system would
enclose this black tank in an
insulated box. Glass or some form
of glazing would be
installed
at an angle
perpendicular to the sun’s rays.
This is a practical, cost effective
passive solar hot water system, ideal
for mild climates.
For more information about this
system check out www.solarnet.org.
8
ACTIVE HOT WATER
Active solar hot water systems are designed for those less gentle climates.
Although they are a bit more complicated and require electricity to run a circulator
pump, active solar hot water systems harvest a lot of energy and save you money.
How much money will they save me on my fuel bill?
Good question. The answer to this question will of course depend on:
1. Your location
2. The orientation of your roof
3. The angle that you position your collectors
4. The number of collectors used
5. How well you insulate the ¾” heat transfer pipes
6. The size of your heat storage vault
7. The amount of insulation used on the heat storage vault
8. The amount of hot water used
You are avoiding my question.
OK it’s a fair question and I’m going to give you the best answer I can from data
on my collector performance and other environmental data. For my four-collector
system with a storage vault of four 55-gallon drums I estimate a minimum heat
energy harvest of 60 fuel oil equivalent gallons per year per collector per year. At a
value of $2/gallon I estimate that a four collector system like this should save at
least $480 per year and pay for itself in less than 4 years at the current cost of
materials if the price of fuel oil never changes. $500 savings per year on Long
Island.
But how about the cost of electricity used to harvest
heat from the sun?
sun?
I wouldn’t worry about that too much. An 85 watt Tyco circulator pump will
consume about 10,000 watts worth of electricity in a year to run the system. At a
cost of $.15/KWH the pump will use $1.50 worth of electricity per year.
9
HEAT TRANSFER THEORY
Before diving into the building plans for an active solar hot water system I’d like to
discuss a few basic concepts regarding light, heat and heat transfer.
How does light make heat?
Most of the sun’s energy that makes the 93,000,000-mile journey is in the form of
visible and ultraviolet light. Heat is produced when high frequency light is
converted into low frequency infrared radiation. Ultraviolet and visible light easily
passes through glass, however when they strike a darkened surface they are
converted into long wave infrared radiation. The glass or special solar glazing traps
these long waves. This is known as the greenhouse effect. CO2 is also capable of
trapping long wave radiation. Small amounts of CO2 keep our planet nice and
warm. Too much CO2 in the atmosphere may transform our forest into deserts. Is it
not ironic that we are using the same effect to save the planet that is destroying the
planet?
Now I understand the Greenhouse effect. Could you
explain what heat is?
Heat is the product of temperature and mass. Temperature measures the average
motion of molecules. When light strikes an object it causes the molecules to
vibrate faster. Intense light can ignite a log or melt steel. The faster an object
vibrates the hotter it becomes. It’s as simple as that.
OK I get it. Light causes molecules to move faster. So
how do these fast moving light excited molecules get
into my hot water system?
They don’t. If they did you would have a contaminated system and you’d get sick
and die, because collector fluid usually contains antifreeze. The molecules that are
excited by the sun never enter your domestic hot water. Only molecular movement
is transferred in the double insulated flat plat plate collector system that I am
proposing.
Wouldn’t it be easier to use plain old ground water for
collector fluid then you wouldn’t need antifreeze?
In gentle climates perhaps, however if you travel north of Georgia the batch tank
would lose too much heat in the evening to be practical. Under extreme conditions
the water in the tank might even freeze. For cold climates it is always best to
separate the heat collection area from the heat storage area.
10
How about that drain away system?
Good point. There is another type of system called the DRAIN BACK system that
allows heated water to drain back into a holding tank when sensors indicate that no
heat gain is possible. Some of these systems employ heat exchange tanks and some
use the solar heated water directly. These systems do save that hot water in the
pipes with a system of automatic valves and relays, but if a valve gets stuck you
might have a problem. Drain Back systems also use high head expensive pumps
that require more energy than closed loop circulator pumps.
OK! You convinced me. Should I get my tools? I feel
like hammering and drilling and sawing and screwing.
That’s good. Hold onto these feelings a bit longer. I want to be sure you understand
a few things about fluid mechanics.
Forget it. I have a friend who is still baffled by the
concept of fluid mechanics and he spent four years of
intense study at R.P.I.
Come on, it will be fun. Think of it as plumbing 101.
That sounds less threatening. I’ll give it a try.
try.
That’s the spirit. I’ll make this as painless as possible and even throw in a few
pictures to liven things up a bit. On the following pages I wish to compare and
contrast two types of flat plate collectors, the parallel and the serpentine. Since the
parallel collector is the most popular commercially available system I’ll discuss
this one first.
11
FLOW RATE THEORY
PARALLEL FLOW DYNAMICS
This parallel collector is designed to transport collector fluid from the bottom of
the collector to the top via a network of parallel pipes. Notice that the top and
bottom pipes are larger than the vertical pipes. There is a reason for this.
Fluid mechanics favors an increased flow rate for the end pipes. This is because
incoming fluid pressure is greatest at the base of the first pipe and outgoing fluid
pressure is smallest at the top of last pipe. If the top and bottom pipes are large the
pressure difference is moderated and the flow rate in each of the parallel pipes is
more uniform. These collectors may be connected in series because the top and
bottom distribution tubes are so large. It is unfortunate that the flow rate is minimal
at the center of the collector where most of the heat is concentrated. Other
problems associated with the parallel flow include cost and leaks. Half inch and
two inch copper tubes are expensive; also there is a leak risk from the dozens of
expensive special T fittings. One small, undetected leak on one T fittings could
become a catastrophic mess.
12
SERPENTINE FLOW DYNAMICS
The serpentine collector consists of one long continuous flexible tube so there is no
problem with uniform flow rate. The size of this flexible tubing is an important
consideration. Quarter inch copper tubing is inexpensive, however it restricts the
flow rate too much. Half inch flexible tubing is difficult to bend and fairly
expensive. 3/8 inch tubing is just right for the money. It has a reasonable flow
capacity, low cost, and ease of fabrication. What more could one ask for?
The main problem with a serpentine collector is flow rate restriction. Even the
larger half inch copper tubing restricts flow rate too much and puts an unnecessary
burden on the circulator pump. Connecting the serpentine collectors in parallel
alleviates this problem. A two-collector system works fine. A four-collector system
works even better. It is very important to bend this 3/8 copper tubing carefully to
avoid kinks. This will insure that the flow rate is uniform throughout the serpentine
collector array hooked in parallel. The following pages demonstrate how two, four
and eight serpentine collectors should be hooked in parallel to maximize uniform
flow rate and minimize fluid pressure on the pump and pipes.
Collectors may be joined from the tops and bottoms or from the sides. Side joined
systems are a bit easier to construct so I have decided to employ this method in my
construction plans. Two, four and eight side-joined collector systems are
illustrated.
13
14
15
Top and bottom joined systems are also illustrated. Please note that my assembly
instructions call for side joined systems.
TWO COLLECTORS TOP AND BOTTOM JOINED
16
FOUR COLLECTORS TOP AND BOTTOM JOINED
EIGHT COLLECTORS TOP AND BOTTOM JOINED
17
Now that we know what the serpentine collector looks like lets see if we can pop a
few together. My construction building plans are for the side joined systems,
however you can easily modify these plans if you decide to construct a top and
bottom joined system. Order the necessary Kalwall glazing now, if you haven’t
already done so, as it may take a few weeks to receive your order. I recommend
that you purchase the .060 inch thick Kalwall even though it costs a little more
than the .040-inch stock. You will need one 4X8 sheet for every collector you
build. You can save a little money if you purchase a fifty-foot roll. The fifty-foot
roll is good for 6 collectors. If you are using a 4-collector system you might be able
to talk a neighbor into purchasing two of your collectors to pay for the entire
project.
To order online go to www.solar-components.com and tell them JC sent you.
18
II
Absorber Plate Construction
Solar Collectors would not be very practical without absorber plates.
Absorber plates increase the surface area exposed to sunlight. More than
700 linear feet of copper tubing would be required to cover the same
surface area that could be covered with 60 linear feet bonded to a wellconstructed absorber plate.
Copper absorber plates facilitate the soldering of copper tubes, but they are
expensive, heavy, difficult to fabricate and unnecessary. Aluminum
absorber plates are less expensive, lighter, and easy to fabricate. You
should be relieved to know that my design calls for aluminum absorber
plates. Did you know that aluminum is a superior conductor of heat?
That’s nice to know but how do you expect me to solder
a copper tube to an aluminum plate?
I don’t. A metallic bond of copper to aluminum requires a special helium arc set
up. The process is time consuming and expensive. We’ll be using tar.
Sounds a little sticky to me.
It is sticky. That’s the point. Tar also provides a good conducting medium. If you
have ever walked on a hot tar roof you’ll know what I mean.
OK tar sounds good. How large should
should this absorber
plate be?
The aluminum plate should cover the largest possible area inside the collector. The
inside dimension of a 4X8 collector would be 46½” X 94½ “. The width of the
absorber plate should be less than 46½ ” to accommodate the semicircle bends of
the copper tube.
19
So… the width of the absorber plate should be about 40 inches. The starting length
of the plate should be 100 inches. After 16 grooves are pounded into the aluminum
sheet the length should shrink about 6 inches. So … the finished absorber plate
should measure about 40 X 94 inches.
You may have difficulty finding sheets of aluminum that are 40 X 100 inches. Two
20 X 100 inch sheets work fine. If you purchase a 50-foot roll of 20-inch
aluminum flashing you will have enough for three collectors. A 67-foot roll would
be just right for four collectors, but I doubt that such an animal is commercially
available. You’ll need two 50-foot rolls for a four collectors, or three 50-foot rolls
for eight collectors. A fifty-foot roll of 20-inch aluminum flashing costs about $30.
What else will I need?
Good question. Might as well get everything you need in one trip.
Tools and Materials for Absorber Plate Construction
1.
2.
3.
4.
5.
6.
7.
8.
Two 50-foot rolls of 20-inch aluminum flashing for four collectors.
Four 1X6X8’s common pine. (Actual size ¾” X5½” X8’)
Two 7/16 inch steel rods.
Heavy hammer.
Tin snips.
One pound of 1 ¼ - inch drywall screws.
Hacksaw.
One gallon of roofing tar and a throw away brush.
Are we ready?
Let’s go.
20
I recommend that you work on a level concrete floor.
First you’ll need to build what I call a pounding jig. This jig will be used to pound
16 grooves into each 20 X 100 inch sheet of aluminum.
Pounding Jig Construction Instructions
1. From the wood that you purchased make four 1X6X4’s and seven 1X6’s 20
inches long.
2. Take the remaining piece of 1X6 and cut off a ½ inch strip. The width of this
strip should be precisely ½ inch. It will be used as a reference spacer.
3. Rip the remaining piece in half to make two 1X2’s 20 inches long
4. Place the eight 1X6X4’s in a row on top of the concrete floor with half-inch
spaces between them. This will be the base of the pounding platform. The
base platform should measure 24 inches by 48 inches.
5. Screw a 1x2 onto one end of the base platform with drywall screws
perpendicular to the base platform. Now secure a 20-inch 1X6 ½ inch from
the 1X2. Use the reference spacer between the 1X2 and the 1X6 to get
accurate spacing. Be sure all the 1X6 boards are also perpendicular to the
base platform and spaced ½ inch apart.
6. Fasten the top layer of boards to the base platform with 1¼-inch drywall
screws. The most important consideration in the construction of this jig is
the spacing between the boards. The ½ inch spaces should be centered 6
inches apart, and the pounding jig should look something like this when
you’re done. I will now refer to the spaces between the boards as slots.
Now for the pounding
21
1. First cut some aluminum sheets 100 inches long. You will need eight
20X100 inch strips for four collectors.
2. Cut a 7/16” steel rods in half so that you have two rods 24 inches long.
3. Lay the aluminum sheet on top of the pounding jig so that one end of the
sheet extends 3 inches beyond the center of the first space. It is important to
get off to a good start so I recommend that you center the aluminum sheet on
the pounding jig. The edge of the aluminum should be parallel with the edge
of the pounding jig platform. When the sheet of aluminum is properly
centered with one end protruding 3 inches from the center of the first space
place your knee on the aluminum to hold it in place and carefully press the
rod into the first ½ inch slot like this:
4. Now you must pound the rod into the slot to create the first groove like this:
22
5. Pound the rod till it is flush with the top of the aluminum like this:
6. Now place plywood or a nice flat board on top of the imbedded steel rod and
pound the board till you are sure that the rod is flush with the top of the
aluminum. I call this board the stabilizer board.
23
7. Now put some pressure on the stabilizer board to hold the aluminum
in the correct position and move on to the next space. Press the rod
into the second slot and pound it flush like you did to create the first
groove.
8. Now slide the stabilizer board over second groove and pound away until
your satisfied that the rod is flush with the top of the aluminum.
24
9. Keep on trucking. You’ve got 14 more grooves to make before this
absorber plate is complete.
10. There are only eight slots for making grooves on this pounding platform, so
you will need to slide the aluminum down after making the first eight
groves. Place the last two groves inside the first two slots. Be sure to line up
the sheet parallel with the pounding platform. Now press rods into the last
two groves that you made on the first run. Hold the rods in position with the
stabilizing board and your knee and continue the process until you make all
16 groves.
Congratulations! You have just made your first absorber plate. Now all you have
to do is pound out 7 more and you’ll have enough for a four-collector system.
25
The absorber plate should look something like this:
Guess it might seem a bit crude, but believe me it works. Once the serpentine tube
is bonded to the groove with tar and the absorber plate is coated with a lampblack
tar coating it will look something like this close up. Notice how the absorber plate
wraps around the copper tubing.
26
III
COLLECTOR BUILDING
INSTRUCTIONS
Before embarking on this project you might consider clearing out the garage or
finding another suitable work area.
STEP ONE
Cut framing boards
Take those carefully selected, straight 1X4’s with few or no knots and miter the
ends. The sidepieces should measure eight feet from tip to tip. The top and bottom
pieces should measure 4 feet from tip to tip. Paint the mitered end grain with your
oil base paint before assembling the frame. This is an excellent weather proofing
precaution.
27
STEP TWO
Assemble the frame
Find a nice hard level surface and assemble the frame like this. Be sure the length
is eight feet between the outside corners and the width is four feet between corners.
You could attempt to screw the corners together if you like, but you may find it
difficult to hold them in place while driving a screw.
I like to gently throw the 4X8 CDX plywood on top of the 1X4’s. One or two of
the 1X4 may fall down, but they can easily be put back in place. The important
thing is to line up the 1X4’s under the plywood one at a time. Make sure the
outside edge of the 1X4 is flush with the plywood and the corners of the plywood
line up with the outside tips of the 1X4’s.
Once the plywood is nailed or screwed into the 1X4’s the corners may
easily be joined with 2” drywall screws.
28
STEP THREE
Fasten the collector bottom and sides
Carefully place the CDX plywood on top of the 1X4’s. Be sure that the outside
corners of the 1X4’s meet the corners of the CDX plywood before nailing down
the plywood bottom of the collector. Place the 1½-inch nails about a foot apart and
throw in a few more near the corners. Predrill 1/8-inch holes into the 1X4 corners
and screw in some 2-inch drywall screws to secure the corners.
Make all your collector frames at once and then paint them inside and out with an
oil base paint of your choice.
Now take a break. You’ve earned it, and besides you’ll have to let the paint dry for
a few days before giving a second coat. If it becomes impossible to wait for paint
to dry you could spend some time working on the 3/8 inch copper tube-bending jig.
29
STEP FOUR…. Construct tube-bending jig
Take those four 1X6X8’s and cut them in half so that you have eight 1X6X4’s. Cut
semicircles on the ends of the 1X6 boards and then make 8 boards like this one.
Now cut each of these boards in half, and flip a collector frame over so that its
plywood bottom faces up. Center the bending jig boards on top of the collector
bottom in the manner demonstrated below. Use a half-inch reference spacer board
to position the bending jig boards so that they have a half-inch gap between them
and screw them into the CDX plywood with drywall screws. Two screws in each
board should be sufficient. Use a carpenter’s square to trace out guidelines on the
collector bottom. This will help you secure these 1X6 boards in this manner
demonstrated.
30
STEP FIVE
Bend copper tubing.
If you have carefully laid out the bending jig and have spaced the bending jig
boards correctly you should have no difficulty bending the copper tubing. Keep the
tubing snug when you press it down into the grooves, but do not put kinks in the
tube. Kinks restrict the flow rate and lower collector efficiency. If you do put a few
small kinks in the tubing don’t shoot yourself. With a little TLC you can squeeze
kinks out with the help of vice grip pliers.
You will be bending a sixty-foot coil of 3/8 inch ID copper tubing into the tube
bending jig slots from one end of the jig to the other. A friend may prove useful. If
you don’t have a friend to help you may wish to hold the start end down with a
board and a few screws. Start the tube about a foot from the top of the first loop so
that you have enough tube for the entire serpentine bend. The bent tube will look
something like this when you are done:
Find a good place to store your serpentine tubes. DON’T KINK THEM. Give all
the collector frames at least two good coats of oil enamel paint. After the collector
frames have thoroughly dried you can check yourself into a nearby mental hospital.
Say hello to my wife while you’re in there. Only kidding. If you have come this far
I think you’ll make it. Hang in there you are doing fine. Now go on to step 6.
31
STEP SIX. INSTALL INSULATION AND SUPPORT SQUARES
Turn a collector right side up and install a 4X8 sheet of one-inch ridged isocynate
insulation with a foil back. Place the insulation inside the collector foil side up and
trim off the excess with a drywall knife so that the insulation fits nice and snug.
MARK INSULATION: Mark the insulation where the copper tubes will go. The
lines should be 6 inches apart. The first line and last line should be 2¼ inches from
the inside edge of the collector frame. Now rip 5¼-inch strips of ½- isocynate
insulation and glue these pieces (with contact cement to the back of the absorber
plate as illustrated below. These squares will help position and support the
absorber plate.
32
STEP SEVEN
Drill inlet, outlet and vent holes
The absorber plate grooves will hold the serpentine copper tubing that you bent.
Before unrolling these groovy absorber plates I’d like you to drill four ¾-inch
holes into the sides of your collector frame. The inlet and outlet holes should be
centered to accommodate the inlet and outlet positions of the serpentine tube.
Center the inlet and outlet holes 3 inches from the collector corners and about 2
inches down from the top rim of the collector frame. A distance of 90 inches must
separate the inlet and outlet holes.
You will also need a few vent holes in the bottom side of your collector to vent
trapped collector moisture. Vent holes should be centered on the bottom side of the
collector one foot from the corners and 1½ inch down from the collector’s top rim.
Center the vent holes one inch down from the top and one foot over from the
bottom side corners.
The ¾-inch holes may seem a bit large but there is a reason for this. Half inch
copper union connectors will be inserted into the inlet and outlet holes. The space
between the tube and the wood will be filled with clear silicon caulking.
These vent holes are for the right collector. The left collector will have vent holes
on the other side. All vent holes should be on the bottom side of the collectors.
33
STEP EIGHT
Install absorber plate
Now unroll two absorber plates into the collector body, groove side up and overlap
them in the center of the collector body. Overlap the absorber plates so that their
outside edges are 4 inches from the inside edges of the collector sides. A distance
of 90 inches should separate the end grooves. You may wish to trim the ends of the
flashing to fit the collector body.
STEP NINE
Install serpentine tubing
If you did a good job bending the 3/8 inch tubing, installing it into the collector
body will be a piece of cake. Handle the tubing with care. You have come this far
without a kink; why spoil it now? Gently glide the tubing into position. This
serpentine assembly should measure about 94 inches long and be 45½ inches
wide.
34
Congratulations! Your collector should look something like this after the
serpentine tube is inserted. If you examine this three dimensional collector closely
you will notice that it has 14 groves instead of 16. This is merely a pictorial
representation of the actual collector. Your absorber plate should have sixteen
groves and the serpentine tube should fit into these groves, if they don’t, make the
necessary adjustments before continuing. Do not press the tubes into the grooves
yet.
Join 1/2 ID copper pipes to the 3/8 ID copper tube with adapter sweat fittings and
allow the ends to protrude through the predrilled ¾ inch holes. The solid
protrusions from the collector represent ½-inch copper tubes. These tubes will later
be trimmed to fit sweat unions that will fit snug against the side of the collector.
35
What is a sweat union?
A sweat union is a special fitting that allows copper pipes to be joined with
compression nuts. It looks like this:
First copper tubing is soldered to the union fittings like this:
Next the union nut is tightened onto the union fittings to join two copper pipes like
this:
The nice thing about unions is that they are temporary connections. If you decide
to move your collectors to a different location some day, unions facilitate the
move.
36
STEP TEN
Install sweat unions
Now we shall connect some unions to the inlet and outlet ends of the ½-inch
protruding copper pipe. Before doing this trim the ends of the copper so that it
extends only ¼ inch beyond the outside of the collector. Mark the pipe before
sliding it out and cutting it. You will need to push the inlet and outlet ends of the
tube beyond their natural resting position in order to trim them to the proper length
and to insert the union fittings. To do this without kinking the tube carefully lift the
tube bends over the collector rim and slide the inlet and outlet ends out.
Now slide the female union nut over the ½-inch inlet end and be sure that the
threads are facing away from the side of the collector. Slide the connecting nipple
onto the end of the pipe and solder it in place. The back of the female union nut
should rest flush with the outside of the collector after you put the serpentine tube
back into the collector body. Do the same for the outlet end.
The assembly should look like this:
After the serpentine tube is put back inside the collector body the union nut should
look like this:
37
The mounting and joining of collectors on the roof will be easy if you do a good
job of fastening unions to the inlet and outlet ends of the collectors. A ½-inch T
with two joining nuts and copper tube extension may be assembled on the ground
to facilitate the collector mounting process on the roof.
This assembly looks like this:
This assembly will later be used to join two collectors in parallel. Two inlets are
joined at the bottom and two outlets are joined at the top with unions and T fittings.
Don’t worry about this now. Let’s finish building our collectors first.
Next we will build a few supports to hold the serpentine tube firmly inside the
grooves.
38
STEP ELEVEN
Cut serpentine tube supports
Rip one 1 X 4 X 8’s in half so that you have two 1 X 2 X 8”s. Rip another 1X4 so
that you have a 2½” piece and a 1” inch piece. Put a beveled edge on the 1X2’s.
These boards will be used to hold the serpentine copper tube in place. You will
need to trim these boards to fit nicely into the collector body, but let’s worry about
that later.
That was easy enough. Don’t you wish life could be this easy?
39
STEP TWELVE
Install tube supports
Press the serpentine tube into the absorber plate grooves. Tube supports hold the
tubes in place and press them tight into the absorber plate grooves. You may need
to notch the bottom of tube support by the inlet and outlet holes. The beveled edge
is not entirely necessary. It is just a little finishing touch that allows more light to
strike the collector. The beveled edge should slope toward the center of the
collector.
Now cut the side supports to fit inside the collector body. They should be about 94
½ inches long. Screw them into the side of the collector from the inside with 1¼inch drywall screws. Press the supports into the edge of the tubing to hold the
tubing snug inside the absorber plate groove.
Now install the central support, 94½ X 2 inches. This support like all the supports
should stand upright. Center this support so that the top edge is flush with the top
edge of the collector. Drill some 1/8-inch holes through the sides of the collector
before joining the central support with 2-inch drywall screws. One screw in each
end is enough. To stabilize the central support screw one 3” drywall screw into the
center of the central support through the CDX plywood bottom. Do not drill
through the copper tubing and do not over tighten this screw. Snug is fine.
It should look something like this when you’re done:
40
STEP THIRTEEN
Paint the absorber plate
So far so good: the copper tubing is secured in place and you are almost ready to
nail down the Kalwall glazing and break for lunch, but there is one picky thing that
we should take care of before we batten down the hatch. Paint the grooves with a
mix of tar and mineral spirits, mostly tar. The tar will bond the copper to the
aluminum and enhance the conduction of heat from the absorber plates. I suggest
that you paint all the installed absorber plates at one time.
It’s best to lay them out flat in a sunny spot where they can dry easily before giving
the final coat of absorber paint. You could buy some expensive selective coating if
you like or you could mix up a batch of my top-secret absorber paint and save a lot
of money. It consists of lamp black, tar and mineral spirits. Equal volumes of each
work good for me. You’ll need about a gallon of the stuff. (Lamp Black can be
purchased as a masonry supply. It’s used to color cement.) Leave the installed,
painted collectors in the direct path of a hot sun for a few days to let them dry out..
STEP FOURTEEN
Install Kalwall
You will need four ½ X ¾ inch painted strips. Miter the ends so they fit together as
demonstrated in the picture below.
Place the 4X8 sheet of Kalwall glazing on top of the collector. Carefully center this
sheet and temporarily tack down one edge. Use a few # 4 finishing nails through a
scrap piece of ½ inch strip of wood. Do not drive these nails home because you
will be removing them shortly, they are used to hold the Kalwall in place while
you run a bead of clear silicon caulking along the edge of the collector under the
glazing. You might want to have a friend hold up the Kalwall while you apply the
bead of caulking.
Next run a thin bead of caulking on the top edge of the glazing and push the
½ X ¾ inch top trim into the wet caulking and nail it down with #4 finishing nails.
Remove the temporary trim, and caulk the remaining edges of the collector in a
like manner. Now nail down side and top pieces. The center top trim should not be
nailed. Caulk under the center strip, press the center strip into the caulking, drill
1/8 inch holes evenly spaced across this strip and screw it down with ¼ inch round
head brass wood screws.
You are almost finished. As long as you have the caulking, squirt some in the inlet
and outlet holes to seal the tubing in place. If you have some ½ inch copper tubing
handy, cut off a few one inch pieces, apply a little silicon caulking to the vent holes
and shove the tubes into them. Allow each of the tubes to protrude about ¼ inch.
41
CONGRATULATIONS! You have just built your first serpentine solar collector.
The others should go easy now that you have the hang of it.
Your finished collector should look something like this. The top center strip is not
necessary. If you decide to include this strip seal the underside with silicon and
screw it down carefully.
Build three more and then we’ll mount them on your roof.
42
IV
MOUNTING THE COLLECTORS
The problems associated with installing flat plate collectors vary with latitude,
orientation, pitch and type of roof. Installing four flat plate collectors on a flat roof
in Ecuador would be less challenging than installing the same collectors on a slate
roof in Maine with an easterly orientation.
ANCHORING THE ANGLE IRON
The one thing all installations do have in common is their need to be anchored
securely. Angle iron is commonly used to facilitate the process. Typically two
strips of angle iron are bolted into the roof and one strip of angle iron is bolted to
the collectors. Between the roof angle iron and collector angle iron additional
angle iron is used to elevate the collectors into an optimal angle for solar
collection.
ORIENTATION
In North America the optimum orientation needed to maximize solar gain would of
course be that of a Southerly direction. When radiant solar energy is perpendicular
to a surface, heat gain is maximized. If you live in a town centrally located in the
US the optimum angle from the horizon pointing toward the equator would be
about 45 degrees. If you live in Florida you might tilt your collectors 40 degrees
and if you live in Maine you might tilt them 50 degrees. If you decide to maximize
your heat gain in the summer you should lower your collectors a bit, but generally
speaking 45 degrees is a good year round angle for the central latitude of the USA.
If you are centrally located in the United States and have a roof with a pitch of 45
degrees facing south you are an ideal candidate for a simple solar collector
installation. Angle iron should still be used to simplify the installation. It is best to
position a few pressure treated 1X4s under the angle iron. For two collectors use
four 1X4X4s: two placed under the bottom roof angle iron support and two
positioned under the top roof angle iron support. The space between the 1X4s
allows water to easily drain off the roof. Bolt the angle irons through the 1X4s,
through the roof and into the roof rafters. For two collectors you will need eight ¼
X3 inch lag bolts, two bolts for each 1X4. To precisely locate a roof rafter from the
outside of a roof you should drill a small hole from the inside. Don’t worry about
the tiny hole. You can fill it with silicon caulking later.
43
I like to use galvanized angle iron with pre-drilled holes. The ones shown here are
oversized for illustration purposes. Notice the orientation of the bottom angle iron.
Your collectors will rest on this slot so be sure to bolt the angle iron securely to the
roof joist. The top angle iron should be secured in a like manner. Once you decide
on the best elevation for the collectors you could cut some angle iron elevation
supports. You will need 4 one-inch machine bolts with nuts and washers to secure
the roof angle iron support to the collector angle iron support.
After the supports are secured, slide the collectors onto the bottom angle iron and
let them rest on the top support.
Secure the collectors temporarily with a few ¼X1 inch lag bolts through the angle
iron supports. Before hooking up the collectors with plumbing you should build the
storage tank facility.
44
V
HOT WATER STORAGE
All that hot water from the sun won’t help you take a bath on Saturday night if you
don’t have a heat storage vault. In the past I have made the heat transfer storage
vault with an 80-gallon water tank by wrapping it in copper tubing, chicken wire,
bailing wire and cement. It’s messy but it works great. You could do it this way if
you like. If you feel like going with cutting edge technology I’ll have to give you a
little quiz before continuing.
How well do you understand thermodynamic theory?
What is thermodynamics? Haven’t I suffered enough?
Thermodynamics is the study of heat transfer. Answer this question correctly and I
will never ask you another.
Promise?
Promise. If you want cutting edge you should understand something about
thermodynamics. This question should help clarify some basic principles of heat
conservation and heat loss.
Lay it on me.
Ralph goes to a diner and orders a cup of coffee. He tells the waitress that he wants
his coffee hot and light. The waitress pours him a cup of scalding hot coffee and
points to the creamer.
Ralph realizes that he needs to use the washroom, but he wants his coffee to be as
hot as possible when he returns. The question is: Should Ralph add the cream
before or after the trip to the washroom?
Beats me. How did your wife answer this question?
She said he should put a saucer on it.
I like that answer.
Me too. It demonstrates an understanding of heat conservation through the use of
insulation, but you and my wife are both avoiding the question. Want to take a stab
at it?
OK!
I say he should add the cream when he returns.
45
Wrong!
How come?
Let’s think about this. We are concerned with heat loss. Which system will cool
down at a faster rate?
A small volume of scalding hot black coffee… or
A large volume of less hot light coffee
The small volume of scalding hot black coffee will cool down at a faster rate than
the large volume of light coffee because the temperature difference of the black
coffee and the air is greater. Large volumes also cool down slower than small
volumes; therefore if Ralph adds the cream to his coffee before leaving he’ll return
to the hottest cup of coffee possible.
OK! Good for Ralph. He got a hot cup of coffee. What
does this have to do with solar hot water storage?
I thought you’d never ask. Solar hot water systems are basically systems designed
to transfer heat from the sun into a heat storage vault. The heat storage vault is
used to preheat ground water before it enters your regular hot water heating
system. Remember how Ralph’s hot coffee cooled at a faster rate than his less hot
coffee? The same principle of cooling applies to heating.
PRINCIPLE
Heat transfer rate is maximized when the temperature
difference between objects is the greatest.
THEREFORE: Heat is transferred at faster rate to the bottom of a tank than to the
top of a tank, because the bottom of a tank of water is colder than the top. This is
true because hot water is lighter than cold water. Cold water sinks, hot water rises.
THEREFORE:
Cold water fed into a collector will transfer more heat from the
sun than hot water.
THEREFORE:
If the hot water storage tank is too small the temperature
difference between the fluid entering and leaving the collector will soon become
negligible and heat transfer will be minimized.
HOWEVER:
If a tank is too large it may never or rarely reach the desired
temperature even if one takes advantage of the layering phenomena of hot and cold
water.
46
MULTIPLE TANK STORAGE SYSTEM
Taking all of these concepts into account we can design a Heat Storage Vault that
will maximize heat transfer by using multiple tanks.
Tank 3 would always be the warmest because this is the first tank used to transfer
collector heat by pumping hot collector fluid through a heat transfer coil. The
second tank is heated in a like manner though it will never get as hot as the third
tank. Call tank 2 the warmer tank. Tank 1 is designed to suck the last bit of heat
from the already cooled collector fluid. This is the warm tank. Collector fluid
returned from this tank will be nice and cold and ready for efficient heat transfer
when it’s returned to the collector.
This series of tanks is designed to preheat water in three successive stages. This
minimizes heat loss in tank 3 and delivers the hottest possible preheated water.
Notice that the collector fluid coils are located near the bottom of the tank and the
domestic hot water coils are located near the top of the tank. Why is that?
That’s
That’s because heat from the collector fluid is best
transferred into the coldest area of the tank and the
highest temperature possible for heat extraction into
domestic hot water is near the top of the tank.
Very good! I’m impressed. How’d you like to teach a course in thermodynamics?
No thanks, but I do have a question for you… What is a
heat exchange coil?
Good question. The diagram above is very simplistic with straight tubes in the area
that would be best for heat collection. The problem with this over simplistic
47
diagram is that it wouldn’t work very well because there isn’t enough surface area
for good heat transfer.
A heat exchange coil is an excellent tool for exchanging heat in a small area like
the inside of a 55-gallon drum. It looks something like this:
Where do I get these heat exchange coils?
You make them.
You’re killing me, man. My knuckles are still sore from
bending those serpentine things for the collectors.
Oh don’t be such a crybaby.
It’s easy. You’ll be using flexible, pre-coiled copper tubing. All you have to do is
cut off a few pieces, make a few adjustments and do a little soldering. Anyhow
don’t worry about heat exchange coils right now; we’ll get involved with them
when we discuss plumbing. How are your carpentry skills?
Good.
48
If I asked you to frame out a box three feet high with an inside measurements of
100 inches long and 28 inches wide would you be able to do it?
I think so. What should I use to build the frame?
2X3’s, 1X4’s or 2X4’s.
Let’s use 2X4’s spaced 16 inches apart so that we may later add insulation. The
size of your particular heat storage vault will vary depending on the number and
size of the tanks that you use, but the basic structure will be the same. Do you think
you could adjust the size of your storage vault based on the particular size of the
tanks you get?
I think I could.
I’m sure you can. I have the utmost confidence in your ability. Let’s get to work.
The tank vault instructions are for a three-tank system. I recommend that you build
a four tank system or larger for a four collector array.
49
VI
HEAT STORAGE VAULT CONSTRUCTION
STEP 1.
Tank preparation
Gather up some water tanks. I recommend that you that get four 55-gallon drums
for a four-collector system. They must be waterproof and rust resistant. If they are
not rust resistant you must paint them with two or three coats of polyurethane. Let
the paint dry thoroughly between coats.
STEP 2.
4X4 supports
Cut eight 4X4s 7 inches longer than the diameter of your tank.
Lay them out on your basement floor where your vault will go. Fill the spaces
between the 4X4s with sheet insulation after you position them correctly. You
should locate the vault near the oil burner to facilitate the plumbing hookup.
STEP 3
Bottom platform
If you would like to use the heat storage vault to heat water and also heat your
house leave a four-inch gap between the tanks and also a leave a four-inch gap
between the tank perimeters and the inside of the heat storage vault.
Measure the largest diameter of your tanks. So if your tanks are 24 inches in
diameter and you’re doing the three-tank system cut a piece of ½ inch CDX
plywood 32X88 inches. Now place the plywood platform onto the 4X4s as
illustrated on the following page. It is not necessary for the edge of the plywood to
meet the edge of the 4X4s. The 4X4s are used to support the weight of the tanks.
Run a few screws through the plywood into the 4X4s to hold it in position while
you frame the walls
50
THE BOTTOM PLATFORM
STEP 4
Placing tanks on the platform
Place the tanks on the platform to make sure you measured everything correctly.
You should have a four-inch border from tank to the edge of the platform.
51
STEP 5
Framing the storage vault walls.
Walls are easy to frame so get out those 2X4s. The first thing to determine is the
height of your walls. Determine the distance from the floor to the top of your tank.
Add at least four inches to this height. This will allow for the connecting pipes and
insulation that you will later add. If you measure 36 inches from the floor to the
top of your tank, the top of the heat storage vault should be at least 44 inches high.
Subtract the thickness or the top + bottom plate (3 inches) to calculate stud height.
Stud height =(vault top height) – (3 inches). Cut all the studs needed for the frame.
The quantity will probably be a few dozen.
Next determine the length and width of the storage vault.
The width of the platform is the length of the sidewall frames. Cut four studs this
length to make the top and bottom plates of the sidewall frame.
The length of the front and back walls is the length of the of the bottom platform
plus seven inches. Cut four studs this length for the top and bottom plates of the
front and back walls. Nail them together.
Hint: 12D nails are sufficient. Nail through the plates into studs 16 inches on center
or less. Use two through the top plate and two through the bottom plate. Do not
toenail through the studs into the plates.
52
STEP 6
Insulating the storage vault
Insulate the vault with 15-inch R13 fiberglass insulation with foil backing. It would
be best if you install the insulation from inside the storage vault. If you haven’t
already done so, remove the 55-gallon drums, as it will be difficult to staple
insulation from the inside with those drums in there. Staple the foil flaps onto the
inside frame. Now take a plastic drop cloth and staple this to the inside walls of the
vault frame. A piece on the bottom platform would not hurt. The inside of the vault
will become very moist from the hot water stored in the tanks. By insulating from
the inside and by lining the inside with plastic we can prevent moisture from
damping out the insulation. Put the tanks back now.
STEP 7
Installing sides to the heat storage vault
You could finish the sides of the chamber with almost anything. Use drywall,
Luan, chipboard or whatever you like.
53
STEP 8.
Installing sheet insulation
Slide 1-inch insulation boards between the drums and the plastic lined tank. This
will increase the R-value of the walls and further retard the damping of the
fiberglass insulation.
STEP 9.
Making the top lid
You could make a nice top lid with ¾ inch plywood.
…And there you have it: you’re very own nice neat Heat Storage Vault
Now all you have to do is hook up the plumbing and run a few sensors. Mr.
Sunshine will soon be working for you. Good job. Take a break. Just have your
plumbing tools with all the fittings and ¾ inch copper tubing ready for tomorrow.
54
VII
HEAT EXCHANGE COILS
Before you assemble heat exchange coils I wish to discuss fluid mechanics again
since it is so important for the success of this project. The rationale for hooking
pairs of serpentine collectors in parallel has been explained in Chapter One. This
system was devised to maximize heat gain at a minimal cost by maintaining
uniform flow rate in both collectors while putting minimal stress on the circulator
pump. An important concept to remember is that flow restriction should never be
less than the flow restriction of the carrier pipe. Since we are using a ¾ inch carrier
pipe the restriction to flow should never be less than this if possible. This is why I
recommend the four collector parallel system. A two-collector system would work.
A four or eight collector system would work better.
THEORY
Since the heat exchange system within the heat storage vault is on the same circuit
as the heat collection system we should be mindful of our flow restriction
limitations.
Here is a simplified schematic of a four-collector system:
Notice that the four serpentine collectors are nicely hooked in parallel, but
something is missing. That’s right, the heat exchange coils are missing. Without
them we won’t be able to store the heat we collect from the sun. What kind
plumbing system do we want inside our heat exchange tanks?
55
If we decide to employ a parallel heat exchange system like the one we are using
with the serpentine collectors, 3/8-inch copper tubing coils joined in parallel could
be used. Each coil would exchange heat with each tank in a uniform manner.
With this system all the heat storage tanks would always be at the same
temperature. This situation is not ideal from the thermodynamic point of view that
was discussed in chapter 2.
56
If you like the idea of fabricating heat exchange coils by connecting coils of ½ inch
flexible copper tubing in parallel you may decide to employ the next system of
heat exchange. Notice that this system uses four parallel heat coils joined in series.
Parallel heat exchange coil made from two half- inch coils:
57
The ½ inch parallel heat exchange coil system is acceptable from a thermodynamic
point of view because the coils are joined in series to allow for storage tank
temperature gradations. They are also acceptable from a fluid mechanics
perspective because this parallel flow system would not significantly restrict flow
rate. The problem with this coil has to do with difficulty of and cost of
construction. If ¾-inch flexible tubing is not available, consider fabricating the
parallel heat exchange coil using these steps:
Cut two 9-foot ½-inch coils. As you probably know, flexible copper tubing comes
in a coil. Use this fact to your advantage. Do not unravel the coil to measure it.
Step 1. Carefully shape these coils to fit inside 55-gallon drums.
Step 2. Clean and flux all fittings and tubes about to be joined.
Step 3. Place (½ to ¾ adaptors) on the ½-inch tube ends.
Step 4. INLET SIDE
Connect two ends with a ¾ inch T as shown above.
Insert a ¾-inch street elbow into the T.
This elbow should be inside the helix pointing up.
Insert a 3-foot length of ¾-inch tubing into the elbow.
Solder these connections.
Step 5. OUTLET SIDE
You should now be looking at a helix with three loops.
Remove one of the adaptors.
Trim that end to the appropriate length and reinstall the adapter.
Insert ¾- inch street elbows into the ends of the helix.
Insert ¾-inch street elbows into the street elbows.
Join these street elbows with two ¾-inch nipples and a ¾-inch T.
The open end of the T should point toward the center of the loop.
Insert a street elbow into this open end.
Insert a ¾ inch copper pipe into this elbow.
This outlet pipe should be pointing up like the inlet pipe.
Now solder all the outlet side connections.
Although you could fabricate heat exchange coils in this parallel manner I
do not recommend it. I have a much better, much simpler coil in mind that
you can make from ¾ inch flexible copper tubing.
Thank you.
You are welcome.
58
How flexible is ¾¾-inch copper tubing, and why is such
large tubing necessary?
¾-inch flexible copper tubing is plenty flexible for this project. It comes pre-coiled
so you’ll only need to make minor adjustments to fabricate it unless you want to
knock yourself out with the ½-inch parallel coils method. You will only need one
60 ft long ¾-inch flexible copper tube per coil. Since ¾-inch has the same ID as
the carrier pipe no adapters are necessary. This is the heat exchange coil that I
recommend that you build. The heat gain, heat exchange schematic flow diagram
looks like this:
Notice the simplicity of the heat exchange system. It is simply ¾-inch flexible
copper tubing joined in series with ¾-inch rigid copper tubing.
Would you like to see what one looks like?
You bet.
I’ll give a few instructions after the picture, though I believe its construction is so
easy that you probably won’t need any step-by-step instructions.
59
3/4–INCH SINGLE TUBE HEAT EXCHANGE COIL ASSEMBLY
The coil diameter should be about 2 inches less than the inside diameter of your
heat storage drum. For a two-foot diameter drum you will need about 60 feet of ¾inch tubing. The length of the tube determines the heat exchange rate.
STEP 1. Shape the entire 60 ft. of copper tubing into a neat helix.
STEP 2. Clean and flux two ¾-inch elbows and one ¾-inch street elbow.
STEP 3. Clean and flux the bottom end of the helix.
STEP 4. INLET
Cut, clean and flux a four-foot ¾-inch ridged copper tube.
Insert this tube into a street elbow.
Insert this street elbow into a regular elbow.
Insert the other end of this elbow into the bottom end of the helix.
Solder these fittings all at once so that they look like the picture.
STEP 5. OUTLET
Cut, clean and flux a three-foot ¾-inch ridged copper tube.
Insert this tube into a clean, fluxed elbow.
Insert the other end of the elbow into the top end of the helix.
Solder these connections as depicted in the photograph.
Congratulations! You have just built a heat input, heat exchange coil. You will
need to trim the ends of the ridged copper tubing to fit connecting plumbing. The
heat extraction, heat exchange coils are built in the same manner except that the
length of the ridged copper-connector tubes are shorter.
60
After you have completed the construction of four heat input coils and four
heat extraction coils you can solder them in place. Remove the inner lid boards
from inside the heat exchange vault and place the heat input coils (the ones with
the longest ridged copper input and output lines) into the heat storage drums. After
placing one coil in each drum look down into each drum. You should see
something like this looking back at you.
If you don’t see something like this when you look down into the drum you are
doing something wrong and you should e-mail me.
If you do see something like this then all systems are go and you may commence
with the soldering. A three-tank heat exchange hook up would look like this:
The actual heat input and heat extraction coils would be more compressed and
contain more loops. Heat transfer rate is determined by the surface area of the heat
transfer coils. A ¾ inch ID tube 60 ft. long has a surface area of about 15 square
feet so three coils would have a heat exchange surface area of 45 square feet. Plans
for an experimental heat storage vault can be found at the back of the book if you
decide to do some experimenting.
61
After completing the hookup of the heat input coils, install the heat extraction coils
above them. Remember these coils are flexible so if the heat input inlet tubes bump
into the outlet tubes of the heat extraction coils don’t shoot yourself. Just bend a
little, and bend the coils while you’re at it. The ¾-inch ridged tubing used to
connect the heat exchange coils should rest upon and be flush with the rims of the
heat storage tanks. Try not to set the tank varnish on fire when you solder. Prop
the coils up a bit to make the soldering easy. You may want to cover the soldering
area with aluminum foil.
Making and installing the inner lid
The inner lid should be made of a substance that will not degrade in the presence
of hot water such as ridged plastic or cement board. It should have a snug fit, and
should look something like this when all the notches are cut out and the heat
exchange coils are put into position.
62
The ¾-inch ridged copper tubing that connects the coils together should not rest on
the metal tank. After the inner lid is placed on top of the tanks, slide 1x4s under the
connecting tubing to get the copper off the tank. The 1x4s also provide support for
the heat extraction coils.
The top of the inner lid of the heat storage vault should now look like this.
The inlet and outlet tubes need to be trimmed so that the ends of these tubes are
about two inches below the bottom of the 2X4 top plate of the heat storage vault.
Next drill four 1½ holes in the sides of the heat storage vault to accommodate the
right angle connections you are about to make with the inlet and outlet tubes.
Clean the ends of the inlet and outlet tubes.
Clean and flux four ¾-inch elbows.
Cut and clean 4 one-foot pieces of ¾-inch ridged copper tubing.
Insert one tube into each of the four elbows.
Push the tube end of this assembly through one of the holes that you drilled.
Push this tube from the inside of the vault.
Insert the end with the elbow on it into an inlet or outlet tube.
Solder the elbow in place so that the end of this assembly is now on the outside of
the heat storage vault.
63
The finished heat storage vault should look like this. Notice the two copper tubes
protruding from the side of the vault. The tube on the left is for the ground water
input. It connects to the heat extraction coils with short stems that should be
positioned near the top of the 55-gallon drums.
The tube on the right comes from the heat release coils. This tube carries collector
fluid. A network of pipes will connect this collector fluid output and join it with
the circulator pump to return collector fluid to the collector input junction.
64
VIII
CIRCULATOR AND VAULT PLUMBING
PREPARE A MOUNTING PLATFORM FOR THE PUMP
The pipes connecting the solar circulator pump must be secured onto a stable
surface with pipe straps. The outside of the heat storage vault provides an excellent
mounting surface for the pump. Secure a 2X4 into the top and bottom sill plates of
the heat storage vault with four 3-inch drywall screws. Position one 2X4 six inches
from the top of the tank and the other six inches from the bottom of the tank.
Now you have something to mount the circulator pump and other plumbing
hardware to. A cartoon version of the plumbing on the outside of the storage vault
would look like the picture on the following page.
65
OVERVIEW OF CIRCULATOR AND VAULT PLUMBING
That’s the basic hook-up at the heat storage vault end except for collector fluid
inlet. This junction is where the carrier pipe comes from the collector and enters
the heat storage vault. We need to add a check valve and a shut off ball valve with
vent like this:
The check valve must be mounted horizontally and open towards the storage vault
to work properly. This valve blocks the flow of residual cold water inside the
collector fluid carrier pipe.
The shut off valve with vent is used to drain the collector fluid. Be sure the vent is
on the collector side of the pipe. To drain the collector fluid, open the drain down
spigot, shut off the drain down valve and open the drain down vent. This vent
allows air to replace collector fluid in the carrier pipe. Once the flow stops you
open the drain down valve to drain the remaining fluid inside the heat exchange
tubes.
66
DETAILED VIEW OF CIRCULATOR AND VAULT PLUMBING:
Note: Shut-off valve B has a vent.
They say a picture is worth a thousand words. You should be able to assemble the
circulator system from this picture.
67
ASSEMBLY
Mount the pump, fill/drain spigot, purge valve spigot, shut-off A, shut-off B(with
vent), dielectric connectors and ¾ copper pipe as demonstrated on the previous
page. Notice the collector fluid return line on the right of the picture. It connects to
a shut off valve with the vent on the right side of the valve. The position of the vent
is very important. When the collector pipes are filled with water the shut off valve
should be closed and the vent should be opened. This will allow trapped air to
escape from the collector pipe system. After all the air is purged from the system
the vent is closed and the shut off valve is opened. Shut-off B also has a vent on
the collector side of the valve to let air into the carrier pipes when draining the
system.
The fill/drain spigot is used to fill and drain the collector fluid from the system.
Dielectric unions are used to connect the copper pipes of the collector fluid system
with the circulator pump. They are used to isolate copper from iron and prevent a
chemical reaction that causes the cast iron pump to rust. The pump may come with
dielectric unions. If not be sure to isolate it with dielectric unions.
The expansion tank should be located a few feet above the top of the heat storage
vault on the collector return pipe. Let it hang down. The expansion tank helps to
moderate pressure inside the carrier pipes of the hot water system. You might want
to install a bleeder valve at this junction to collect and get rid of trapped air.
Trapped air will interfere with pumps ability to circulate. A fill valve is also a
good investment. One of the important functions of a fill valve is to maintain a
constant pressure within the circulator system.
I strongly recommend that you study a standard base hot water heating system
before attempting to build a solar hot water circulator system. If you feel unsure
about any aspect of this system seek the advice of an experienced plumber.
Once the circulator system is complete all you have to do is replace the ground
water connection of your fossil fuel heater with heat output from your storage tank.
This will complete the circulator pump end of the plumbing. BUT before doing
this you must complete the collector plumbing.
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IX
COLLECTOR PLUMBING
OVERVIEW
The four-collector system pictured below is simplified to give a general overview
of the collector plumbing connections. The main junction for the collector output is
depicted as a ¾-inch cross. This cross is rare and expensive so you will probably
make due with a few T’s. That funny looking thing on top represents a pressure
relief valve. If there is a power outage on a hot summer day or the circulator pump
does not go on when it should the collectors may overheat. The pressure relief
valve will vent steam if the circulator pump stops. Details of the main collector
output junction are on the following page.
69
Be sure to have the ½ inch union T assembly ready before climbing on the roof to
begin the collector plumbing.
Half inch union T assembly consists of one ½ inch T connected to two ½ inch
union fittings and a six inch piece of copper tubing. This six-inch piece will later
be trimmed and connected to a collector main junction. You will need four of these
assemblies for a four-collector system.
The 3/8-inch copper tubing of the collectors is terminated with ½ inch unions.
These unions will be attached to the union T assembly These assemblies will be
fitted with elbows and connected to main input and output junctions.
70
MAIN OUTPUT JUNCTION
The main junction of the collector output consists of a pressure relief valve, ¾ pipe
to sweat adaptor, one standard ¾-inch T, one ¾ X ½ X ½ T, a ¾ street elbow, ¾
copper tubing and ½ copper tubing. Additional plumbing is included to clarify
union connections to the collectors.
71
MAIN INPUT JUNCTION
The main collector input junction consists of a ¾ X ½ X ½ T
The proportional sizes of collectors and copper tubes are distorted to clarify the
plumbing connections. The actual length of the ½ inch copper tube connecting the
input junction T with the elbow is about four feet. The tube length between the
elbow and the union junction T would be about four inches. You will need to
adjust the length of these tubes for your particular installation.
72
X
THE SENSOR SYSTEM
A sensor system is one way to make your solar hot water system work
automatically. Sensors compare collector temperature with storage vault
temperature. If the collector temperature is higher than the storage vault
temperature the sensor relay turns on the circulator pump. You may adjust the
temperature difference sensitivity. A 10 degree F difference in temperature is a
good setting. If you make the adjustment too sensitive the pump will turn on and
off without accomplishing very much.
Place a collector sensor close to the collector output. Bind the sensor tightly to the
copper tube with a hose clamp. Connect a second sensor to a heat exchange tube
junction. The best connection will depend on your style of hot water usage. You
can always switch it later. You could instead install a P/V driven pump.
Now that the sensors are in place you’ll need to hook up the sensor relay to the
circulator pump. Don’t plug it in yet. We need to fill the system and check for
leaks before we turn on the pump.
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XI
FILLING AND DRAINING THE
COLLECTOR SYSTEM
FILLING THE COLLECTOR SYSTEM
Fill your solar hot water system with a garden hose from a ground water spigot.
You may wish to install a basement ground water spigot or simply use your outside
garden hose to fill the collector system. You’ll need a female-to-female connector.
A washing machine input hose will do fine.
ONE:
TWO:
THREE:
FOUR:
FIVE:
SIX:
SEVEN:
EIGHT:
NINE:
Hook the hose onto the fill/drain spigot.
Close shut off valve A.
Open shut off valve B.
Open purge valve.
Let water flow through the system until all the air is purged.
Close purge valve.
Close shut off valve B.
Purge the last bit of air from the line.
Shut off both spigots, disconnect the hose and open valve B.
Now you can plug the sensor relay into the circulator pump and try out the system.
If the sun is shining you should feel heat in less than one minute. If everything
looks good you can fill the heat storage vault tanks with water and batten down the
storage vault hatch.
INSULATION:
Don’t forget to place solid insulation on top of the inner lid of
the storage vault. You also need to put insulation on all the collector carrier pipes.
Don’t be cheap with the insulation; a good insulation job will pay for itself in a
very short time.
DRAINING THE COLLECTOR SYSTEM
If there is no danger of the pipes freezing give your system a week or so to break in
before draining it down and adding antifreeze. Measure the amount of water that
you drain from the system. Use this measurement to calculate the amount of
antifreeze to add.
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DRAINING THE CARRIER PIPES:
ONE:
TWO:
THREE:
FOUR:
FIVE:
SIX:
SEVEN:
Close the drain down valve.
Open the fill/drain spigot.
Open the drain-down-valve vent to let air into the collectors.
Let all the water drain from the collectors.
Cap the drain down valve vent
Open the drain down valve.
Let all the fluid drain from the system
ADDING ANTIFREEZE: Calculate the amount of antifreeze necessary for
your system from the amount of water drained in the drain down process. Now
hook up the garden hose and fill the collector system with water using the method
described on page 75. Shut off the water supply when the system is full. Don’t
close the fill/ drain spigot yet. Have a friend stationed by the supply spigot. (not the
fill/drain spigot) Have your friend bleed water from the system at this junction.
He/she could set up a bleeder valve at this junction or just loosen the hose
connection enough to let out a little water at a time on your signal.
You’ll need to set up some kind of communication
between the location of the collectors and the location
of the heat storage vault plumbing.
Get your butt up on the roof and unscrew the pressure
relief valve from the main output junction (page 72).
You should know how much antifreeze your system
needs if you measured the volume of water drained
from the system as on page 74. This is the amount of
antifreeze you should have with you on the roof.
Now signal your friend to gradually bleed water from
the system as you add antifreeze to the main output
junction.
Do this carefully so that no air is trapped in the carrier
pipes. When you have added all the antifreeze and the
fluid level is brimming at the main output junction and your friend has tightened
the hose connection seal the threads of the pressure relief valve with pipe
compound and screw down the pressure relief valve.
Now all you have to do is have your friend turn on the water supply while you
bleed any trapped air by pulling up the leaver on the pressure relief valve.
Congratulations! Turn off the water supply. Close the fill/drain spigot and you’re
ready to rock and roll.
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XII
OTHER SOLAR APPLICATIONS
FORCED HOT AIR HEATING: This solar hot water system is not intended
for home heating. However, a simple forced hot air system may be used to extract
some of the heat from the heat storage vault. If you have left some space around
the hot water tanks you could install a baffle system to guide forced hot air around
the tanks.
Connect ductwork from a floor register on your first floor to the base of one end of
the heat storage vault. The other end of the storage vault may then be connected to
another floor register with ductwork. Install a fan just under one of these floor
registers to force cold floor air down into the storage vault. Hot air should then
enter into the first floor from the other register.
BASEBOARD HEATING: An alternative to forced hot air is conventional
baseboard heating. You’ll need to insert additional heat extraction coils into the
heat storage vault tanks and provide an additional thermostatically controlled
circulator pump.
ELECTRICITY: Electricity may be produced from storage vault heat with a gaspropelled engine. Such engines do exist, but as yet they are not very practical;
perhaps you will design one that is cost effective.
The future looks bright for solar application technology. Our non-renewable
energy resources are becoming more rare and more expensive every day. The need
to burn the fluid remains of ancestors to stay warm is no longer valid. It’s time to
step out of the cave into the light of day and reestablish our life link with our sun.
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GLOSSARY
Absorber Plate:
a heat conductive metallic plate capable of converting
light energy into heat energy
Active Solar:
pertaining to systems that have mechanical devices such
as a fans or pumps to transport heat
Adaptor:
a plumbing fitting used to join different size pipes
Angle Iron:
a long iron strip with a right angle bend
Batch Heater:
a tiny solar greenhouse used to heat a tank of water
Carrier Pipes:
pipes used to transport fluid
Collector Fluid:
a mix of water and antifreeze circulated throughout the
collector system
Collector System: a network of carrier pipes, collectors, heat release coils
and circulator pump
Drain Valve:
a ball valve used to drain a network of pipes
Elbow:
a plumbing fitting used to join pipes at a right angle
Expansion Tank: a tank used to moderate pressure differences inside a
network of pipes
Fill Valve:
a ball valve used to fill the collectors and the carrier pipes
Fill/Drain Spigot: spigot used to fill or drain the collector system
Fluid Mechanics: study of fluid movement
Groove:
that indentation made by a steel rod into absorber plate
used to hold the serpentine carrier tube.
Ground water:
well water, city water or town water
Heat:
product of temperature and mass
Heat Exchange Coil:
a helix of copper tubing used to transport heat
from or to the carrier fluid
Heat Extraction Coil:
a heat exchange coil used to preheat ground water
Heat Release Coil:
a heat exchange coil used to add heat to the water
inside the storage vault tanks
Kalwall Glazing:
a fiberglass reinforced plastic specially designed for solar
glazing applications
77
Passive Solar:
pertaining to a system that utilizes the heat from the sun
without a mechanical interface
Pounding Jig:
a platform used to make the absorber plate
Pressure Relief Valve: a plumbing device that allows excess pressure to
escape from inside a plumbing system
Sensor Relay:
Sensor System:
Slot:
Solar Sensor:
Solar Collector:
Solar Glazing:
Stabilizing Board:
Street Elbow:
T:
Temperature:
Thermodynamics:
Tube-Bending Jig:
Union:
Union T assembly:
a switch activated when sensors detect temperature
difference
a network of heat sensors and a relay used to control the
on/off time of a circulator pump
the ½ inch space on the pounding jig used to make the
absorber plate groove
a device used to measure temperature differences
between collectors and storage tanks
a device used to harvest heat from the sun
a substance that allows visible and ultraviolet light
through while blocking infrared or heat
a board used to hold the aluminum flashing in place
while making grooves in the absorber plate
a plumbing fitting used to make a tight right angle female
to male connection
a plumbing fitting used to join three pipes
the average kinetic movement of molecules
the study of heat
a device used to facilitate the bending of a tube
a plumbing fitting used to temporarily join two pipes
a special assembly used to join serpentine
collectors at both the input and output junction.
78
Hi
Thank's for taking the time to read
about my solar hot water system. I
am presently a home improvement
contractor concerned about the
high cost of energy and the
dwindling supply of nonrenewable
resources. Fossil fuels are much
too precious to use for heating
water. Heating water is just one of
the many things that the sun does
best.
Back in 1980 I started the Adirondack Solar Association and helped organize solar
meetings, tours, workshops and sunspace constructions while teaching general
science in high school. Full time employment in the field of solar energy
technology would be nice; I’m still hoping. Perhaps someday we’ll all be
employed in making better use of the boundless, free energy from sunlight.
I
f any solar thermal concepts from this book are still unclear to you don’t hesitate
with e-mail. Send e-mail to [email protected].
O
r post a message in the forum at: www.JC-SolarHomes.com
79
g{x XÇw
Actually it’s more like the beginning. The field of solar thermal energy
is a new frontier with new possibilities for a new less dependent, more
earth friendly way of living. Cost effective solar applications that make
practical use of the sun’s boundless energy can help us find our way
back to our roots. As the price of oil increases products associated
with oil energy will rise. The cost of transportation, heating, electrical
power and food will become a major concern. I predict that small local
farms will be more valuable in the future and those small businesses
that encourage energy independence will be in a position to flourish. If
you understand how sun energy works you know the tools and materials
to build a better world do not depend on big business and big
government. They depend on natural resources and our ability to use
these resources wisely. Opportunity knocks.
Will we answer the door?
80
Experimental Non Pressurized Heat
Storage Vault with Built in Tanks
You’re probably sick of reading about heat storage vaults by now, but I’ve
got one more for you that will make the others look silly by comparison. As
far as I know this tank has never been built by mortal man or mortal woman
for that matter. This is a cutting edge design that I haven’t had time to test
yet, but I’m confident that it will work. Perhaps you’ll be the first to build it.
If you do, let me know if it’s as good as I think. It should be less expensive,
more efficient and easier to build than any of the other designs. No special
“hard to find” tanks are needed. You’ll build your own tanks from commonly
available construction materials and “… do more with less”.
This project is similar to the last one except that stand alone tanks will be
unnecessary. The idea came to me one day when I became frustrated with
the task of finding a good supply of 55 gallon drums. I see them chained to
posts in parks. I know they wait patiently on the edges of concession stands
and stand proud and tall at beaches, restraints and parking lots across the
nation, but when it comes time to purchase a 55 gallon drum at K mart or
Home Depot the clerks just shake their heads and throw up their hands in
confusion. People are always giving them to me but I never know where to
get them. Anyhow I got crazy one day and said to myself who needs those
rusty old tanks anyhow. That’s when I sat down and designed this simple
vault made from 2x6s, 2x4s plywood, polystyrene foam, siding insulation,
copper tubes, cement and a sheet of plastic. Non-pressurized tanks need not
be made of steel they only need to hold water.
Any water proof container can do that. Swimming pool inserts pressed tight
against pool walls provide an excellent seal against the inevitable leaks that
occur when the earth shifts and walls develop cracks. These inserts would
make an excellent lining for a heat storage vault, but even these hard to get
custom linings are unnecessary. A simple inexpensive polyethylene drop
cloth is all you need to waterproof the inside of a vault.
Why not? What do you think?
81
The base of a 14 foot long vault might be framed with 2x6 PT lumber.
Look familiar?
82
Heat Storage Vault Instructions
First construct a base frame like the one on the previous page.
Pack it with solid insulation before sheathing it with plywood.
Next secure a 2x4 frame to this plywood as shown below.
So far so
good
A network of copper tubes (coated with polyurethane) are then
placed in the hollow of the frame and cemented into position to
provide a heat input exchange area. Polyurethane protects the
copper from the corrosive effect of the cement.
83
VAULT FRAME WITH POLYSTYRENE BARRIERS
I’ll leave the framing of the vault up to you. If you’re not sure
how to frame contact me or find a carpenter.
[email protected]
When you’re done don’t forget to insulate and sheathe the frame,
but don’t break for lunch yet. You need to glue 2” strips of
isocynate insulation to the inside of the vault. These strips should
have a three inch gaps between them. These gaps will later be
used to support 3” polystyrene inserts that form the tank
petitions. The edges of the insulation should be smoothed,
plastered and sanded to avoid tearing the plastic sheet when the
3” polystyrene inserts are installed.
84
After you’re satisfied that the interior of the vault is as smooth as
a baby’s you know what, carefully insert and glue a sheet of
polyethylene plastic onto the vault walls. Use glue that remains
soft and flexible like rubber cement. Press the plastic into the
grooves. Now comes the hard part. Slide the polystyrene foam
barriers between the 3” grooves without tearing the plastic. Sand
the edges of the solid insulation first to avoid problems.
THE OPEN VAULT
If you did a good job, the open vault should look something like
this with some excess plastic hanging out over the sides. The
number of chambers is up to you, but you should have at least
two. Vaults like this could be hooked in series. If you decide that
additional heat storage is necessary it’s an easy matter to build
and install additional vaults.
85
The heat out or heat
extraction tubes is
where heat from the
hottest area of the
storage vault is
extracted into the
radiant heating system
or domestic hot water
system. Notice that the
water is heated in
stages. Each chamber
preheats the water
before it enters the
next chamber.
CROSS SUPPORTS
The cross supports not
only prevent the
chamber from collapsing
under the weight of all
that water, but they also
hold the polystyrene
foam barriers in place.
Without these cross
supports the foam
barriers would be
displaced by the water
and pop out of the
chamber.
86
TOP ENCLOSURE
Fill the chambers with water and than insulate the top of the
vault with solid foam insulation before screwing down the lid. You
could let the foam insulation float if you like but be sure to cover
this insulation with additional plastic to prevent a possible
moisture problem in the basement.
Best of luck with this, and all your solar thermal energy projects.
If you need help you may contact me: [email protected]
87
Greetings Sun Person,
How to Build a Solar Hot Water System should get you off to a good
start with a practical solar thermal energy project. If you follow the
instructions you should soon be saving money with free energy from
the sun. Suggestions are welcome and clarification is provided at:
“Sun Heat University” an online, interactive school located in the
wonderful world of www.JC-Solarhomes.com
Other great books available from Sunny Future Press include:
Solar Thermal Energy is a comprehensive guide into the
practical world of solar applications. This book/CD-ROM show
combination will bring you one step closer to the sun.
Energy Independent Housing will set you free from fossil fuel
corporations forever. Imagine saving fuel oil and electricity, while
reversing the process of land and air pollution.
Solar Heating Projects provides the reader with a step
by step guide to dozens of solar heating projects designed
to save energy and save money. These projects include:
Solar Concentrators, Hot Boxes, Window Boxes, Trombe
Walls, Solar Greenhouses, Batch Heaters, Thermo Siphoning
Systems, Solar Collector Construction, Collector Mounting,
Five Heat Storage Systems, Collector Plumbing, Solar
Thermal Roof Theory, Solar Thermal Roof Construction,
Energy Independence, Solar Cell Theory, Cu/CuO solar cell
construction as well as some solar thermal engine theory.
]É{Ç VtÇ|ätÇ
May the sun forever shine upon you…
88