Download Report

Ford’s RV Training & Service presents
Evaluation of RV Refrigerators:
A side by side independent evaluation of
Atwood and Dometic Refrigerators
1.0 Introduction
The marketplace of RV refrigerators over the last 20 years has been dominated by Dometic
and Norcold with no other competitors. The introduction of a new competitor, namely
Atwood, as well as its use of helium rather than hydrogen, prompted the ownership of
Ford’s RV Training & Service to conduct a side by side independent evaluation. Absorption
refrigeration has used hydrogen since commercial production of absorption refrigerators
began in 1923 so the introduction of a new chemical after all this time is a major change.
This evaluation was conducted with the expressed goal of determining for the consumer
and RV industry how the new helium technology performed relative to hydrogen based
absorption refrigerators by putting like models of refrigerators through a series of tests.
Every effort was made to ensure that the test products were treated equally by ensuring
that conditions for each product were identical.
2.0 Products Tested
The products tested for this evaluation were refrigerators from two different
manufacturers. Though there are three manufacturers of RV refrigerators at this time, one
of the manufacturers, namely Norcold Inc., chose not to participate in this evaluation.
Atwood Mobile Products, LLC (Atwood) and Dometic, LLC (Dometic) donated the required
refrigerators (refer to Table 1 below), cooling units, and associated literature to be used in
this evaluation. Ford’s RV Training & Service would like to express it’s appreciation to
Atwood and Dometic for their willingness to take part in this evaluation showing confidence
in their product.
Table 1 Products Tested
Manufacturer Atwood
Dometic
Atwood
Dometic
Model
HE-0601
RM2652
HE-0801
RM2852
Height (in.)
52.5
53.4
59.4
59.6
Width (in.)
22.8
23.4
22.8
23.4
Depth (in.)
23.7
24.0
23.7
24.0
Fan*
Yes
No
Yes
No
© 2012 Ford’s RV Training & Service
*Fan was disconnected for equal comparison purposes
1
2.1 Product Features
Though the refrigerators tested all utilize absorption refrigeration and the comparisons
were made on models of the same basic size (i.e. 6 cu. ft. and 8 cu. ft.), there are a few
differences that should be noted. Below is a table which lists many of the features. The door
alarm and tilt sensor features of the Atwood models were tested and found to operate as
indicated by the manufacturer.
Table 2
Product Feature Comparison
Feature
Atwood
Dometic
Comments
Absorption
Refrigeration Gas
(Other than Ammonia)
Power Failure Recovery
Helium
Hydrogen
Helium is not flammable therefore
reduces the chances of a chemical fire.
None
Automatic
Door Alarm
Included
None
Door Handles
Pull
Push/Pull
Tilt Sensor
Included
None
Warranty
2 years Limited
Interior Light
LED
2 years
Limited
Incandescent
Refrigerator Storage
Integrated
Latches
If a power failure occurs even
momentarily, the Dometic models start
operation immediately when power is
restored while the Atwood models
remain off when power is restored.
Door alarms on the Atwood models to
indicate that the door was left open
Atwood handle is more intuitive as you
just pull whereas the Dometic handle
must be pushed with thumb while
pulling with the other fingers.
Atwood's tilt sensor indicates operation
at severe angles of inclination
Both manufacturers offer a 2 year
limited warranty
Incandescent bulbs are less energy
efficient and have a shorter lifespan.
The position cards are separate from
the refrigerator. The integrated latch is
built into the door handle.
Airing
Position
Cards
Dometic Door Handle
Atwood Door Handles w/
integrated latches
Dometic ”Eye Brow” Controls
© 2012 Ford’s RV Training & Service
Atwood Controls
2
Atwood Interior Light
Dometic Interior Light
3.0 Test Methods
The methods employed in testing are those based upon the standards established at Ford’s
RV Training & Service which in many aspects exceeds the testing standards in ANSI Z21.19.
The refrigerators were tested under several different running conditions (refer to Table 3
below). Each manufacturer’s unit of similar size was tested under the same conditions at the
same time to ensure proper comparison was maintained. In addition, the refrigerators
being compared utilized identical testing tools and instruments which were used according
to manufacturer’s recommendations unless superseded by Ford’s RV Training & Service
standards and procedures. The refrigerators were tested while operating on both LP and
110V electricity. They were tested while running “free-standing” unless noted as being in a
test enclosure. Free-standing in this case means that the refrigerator is running outside of
an RV enclosure. The refrigerators were tested in a Temperature Controlled Environment
(TCE) which was a room where a heat could be regulated and increased in order to subject
the refrigerators to very high temperatures. Test enclosure testing refers to an apparatus
built to ANSI Z21.19 tolerance standards in which refrigerators were placed for testing. The
refrigerators were tested to compare the effectiveness of each refrigerator under as many of
the actual operating conditions each would face in the marketplace as possible within the
limitations of the testing facilities. In addition to testing under actual operating conditions,
the refrigerators were subjected to additional testing in accordance with the procedures
developed in the 30 years of Ford’s RV Training & Service.
Table 3
Test Methods By Refrigerator Model
LP
110V
Temp. Controlled Environment (TCE)
Test Enclosure
Unlevel Conditions
© 2012 Ford’s RV Training & Service
HE-0601
DM2652
√
√
√
√
√
√
√
√
HE-0801
DM2852
√
√
√
√
√
√
3
3.1 Additional Test Methods
In addition to the tests discussed above, other tests were completed on the refrigerators,
which although they do not directly relate to the compartment temperatures, they do reflect
important information to the manufacturer and consumer as to the reliability and efficiency
of the refrigerators. One such test involved taking the temperatures of the cooling unit in
several locations while attached to the refrigerator cabinet. Other tests included
determining the energy usage of the refrigerators, testing the alarms, and even running the
cooling units “in the raw”.
4.0 Test Results
The results given are those recorded from the raw data sheets which are archived at the
Ford’s RV Training & Service office. During testing, a Type K thermocouple was used in
conjunction with Fluke 902 True-rms HVAC clamp meter to measure temperatures inside
the refrigerator compartment and the freezer compartment. Temperatures taken outside of
the refrigerator were measured with a Fluke 62 Mini IR Thermometer. The 12 volt control
power required was provided by Iota DLS-15 and DLS-30 power converters. A basic
premise of the testing was that each refrigerator was capable of producing like results in all
situations. The results of the testing do seem to bare that out as will be seen in the details
below.
Type K Thermocouple
Fluke 902 Clamp Meter
Iota DLS-30 Power Converter
Fluke 62 Mine IR Thermometer
© 2012 Ford’s RV Training & Service
4
4.1 Overall Average Temperature Results
All test results are given in a manner as to best compare the units in like terms with the
exception of the overall temperature results which may include differing number of data
points depending on the number of points taken for that refrigerator. The overall average
temperatures seen in all refrigerators in all testing conditions were within one degree of
each other and well below the maximum refrigerator temperature allowed by Ford’s RV
Training & Service which is 41°F. It should be noted that the Dometic DM2852 maintained a
lower average temperature than its Atwood counterpart HE-0801. Table 4 given below
details the actual results.
Table 4
Overall Average Temperatures
HE-0601
DM2652
HE-0801
DM2852
Average Refrigerator Compartment Temperature
32°F
32°F
35°F
34°F
Average Ambient Temperature
83°F
83°F
86°F
86°F
Overall Average Refrigerator Compartment Temperature
36°F
35°F
35°F
34°F
34°F
33°F
32°F
32°F
HE-0601
DM2652
32°F
31°F
30°F
HE-0801
DM2852
4.2 Free-Standing Results
As stated above, free-standing refers to the refrigerator being operated outside of an RV
enclosure. The results given in this section are those of the refrigerators while operating
them through the controls on 110VAC power and liquid propane (LP) gas. All four
refrigerator models were operated in this manner in a wide range of temperatures (as low
as 22°F and as high as 113°F). Subjecting the refrigerators to elevated temperatures up to
113°F was accomplished by placing the refrigerators in the TCE. It should be noted that the
two 6 cu. ft. models (HE-0601 & DM2652) had fewer data points in this test method. The
results show that while all models maintained average temperatures well below the
maximum allowed both Dometic models maintained lower average temperatures than the
Atwood models.
© 2012 Ford’s RV Training & Service
5
Average Free-Standing Refrigerator Temperatures
36°F
35°F
35°F
34°F
34°F
34°F
33°F
32°F
31°F
31°F
30°F
29°F
HE-0601
DM2652
HE-0801
DM2852
4.3 Test Enclosure Results
The two 6 cu. ft. model refrigerators (HE-0601 & DM2652) were placed in test enclosures
which were built to ANSI Z21.19 tolerance standards. The enclosures utilized the side and
roof vents supplied and recommended by the manufacturer. While in the test enclosures,
the refrigerators were exposed to a wide range of temperatures (as low as 69°F and as high
as 117°F). The higher temperatures were achieved by placing the refrigerators in their
enclosures in a TCE. Test enclosures were utilized to simulate the environment that the
refrigerators would encounter while in an RV. Specifically, the test enclosures restricted the
air flow at the cooling unit. The chart below shows the average temperatures seen by both
models of refrigerators while in the test enclosure. It should be noted that the HE-0601
model was operated at a thermostat level of four which is one less than its maximum of five
and maintained a lower average temperature than the Dometic DM2652.
Test Enclosure Average Refrigerator Temperatures
31°F
HE-0601
32°F
DM2652
29.9°F
30.4°F
© 2012 Ford’s RV Training & Service
30.9°F
31.4°F
31.9°F
32.4°F
6
Dometic
DM2652
Atwood
HE-0601
6 Cu. Ft. Models in Test Enclosures
4.4 Out of Level Operation Results
The two 8 cu. ft. model refrigerators (HE-0801 & DM2852) were subjected to out of level
conditions while being operated in the free-standing test mode. The conditions were
simulated by utilizing a 1x4 board placed under each of the four sides of the refrigerators.
The 1x4 has a height of ¾” and the placement of the board under the refrigerators equated
to an approximate two degree angle of inclination. Both refrigerators where subjected to
this testing for a minimum of 24 hours at each out of level position. The chart below details
the results of the testing under these conditions. As can be seen in the chart, both the
Dometic and Atwood models average temperatures were well below the maximum allowed
by the ANSI Z21.19 standard though the Dometic model DM2852 did maintain lower
average temperatures than the Atwood model HE-0801 in all four of the out of level
conditions.
© 2012 Ford’s RV Training & Service
7
Out of Level Operation Temperatures
44°F
42°F
40°F
38°F
36°F
34°F
32°F
30°F
Absorber Vessel
(Right Side)
Boiler (Left Side)
DM2852 Average
Cooling Unit (Back)
HE-0801 Average
Doors (Front)
ANSI Z21.19 Max
Dometic DM2852 (left) and Atwood HE-0801 (right) operating in
“free-standing” out of level test mode with boiler side high
© 2012 Ford’s RV Training & Service
8
4.5 Temperature Controlled Environment (TCE) Results
The use of a TCE was necessary to bring about high ambient temperatures. Each model was
tested in this environment for a minimum of 6 days. The 6 cu. ft. models (HE-0601 &
DM2652) were tested in the TCE while in their respective test enclosures. In addition, the
refrigerator compartments of the 6 cu. ft. models were filled with approximately 715 fluid
oz. of water utilizing six 2-liter bottles, one 1-gallon jug, seven 1-pint bottles and one 64 oz.
jug. The 8 cu. ft. models (HE-0801 & DM2852) were tested in the TCE operating in the freestanding mode with empty compartments. For all models, the temperature probes were
located in the front-center of the top shelf of the refrigerator compartment. The thermostat
control was at set point four on both Atwood models (HE-0601 & HE-0801). The ambient
temperatures ranged from 82°F to 117°F with the 6 cu. ft. models having an average
ambient temperature of 112°F and the 8 cu. ft. models having an average ambient
temperature of 96°F.
Average Temperatures in Temperature Controlled Environment
8 Cu. Ft. Ambient
DM2852
HE-0801
6 Cu. Ft. Ambient
DM2652
HE-0601
0°F
10°F 20°F
30°F 40°F 50°F
© 2012 Ford’s RV Training & Service
60°F 70°F 80°F
90°F 100°F 110°F
9
Dometic DM2652 (left) and Atwood HE-0601 (right) operating in their test
enclosures in the Temperature Controlled Environment.
4.6 Cooling Unit Test Results
The cooling units were tested in two different capacities. They were tested while attached to
the refrigerator cabinets and also “in the raw” which means detached from the refrigerator
cabinet with the insulation removed. While operating attached to the cabinet, temperatures
taken of the cooling unit at the steam line just before it enters the condenser, at the top
absorber coil, at the bottom absorber coil, and at the evaporator as it exits the urethane. The
temperatures seen at the four areas taken were within the ranges expected. More
importantly, the temperatures were consistent over time and between models as can be
seen in the charts below. Operating the cooling units “in the raw” allows for a very clear
visual test of the effectiveness of the cooling unit and its associated chemical mixture.
© 2012 Ford’s RV Training & Service
10
Steam Line just before
it enters condenser
Evaporator as it exits
urethane
Bottom Absorber Coil
Cooling Unit attached to refrigerator cabinet while operating “free-standing” in
the TCE. The above markers show where the temperatures were taken which is
typical for all models.
© 2012 Ford’s RV Training & Service
11
Attached Cooling Unit Average Temperatures
130°F
120°F
110°F
100°F
90°F
80°F
70°F
60°F
Steam Line Temp
HE-0601
Top Absorber Coil Temp
DM2652
Bottom Absorber Coil
Temp
HE-0801
Evaporator Exit Temp
DM2852
Attached Cooling Unit Maximum Temperatures
160°F
150°F
140°F
130°F
120°F
110°F
100°F
90°F
80°F
Steam Line Temp
HE-0601
Top Absorber Coil
Temp
DM2652
© 2012 Ford’s RV Training & Service
Bottom Absorber Coil Evaporator Exit Temp
Temp
HE-0801
DM2852
12
The cooling units from the 8 cu. ft. models (HE-0801 & DM2852) were operated “in the raw”
to compare the ice formations on the evaporator. Measuring the length of evaporator
covered by ice revealed that HE-0801 had 34.25” of ice at 79°F while DM2852 had 32.5”.
Measurements taken at 103°F ambient temperature showed that HE-0801 had 22.875” of
ice and DM2852 had 21.75” of ice.
“In the Raw”
Ice Formation (32.5”) on Dometic
Cooling Unit’s Evaporator
© 2012 Ford’s RV Training & Service
Ice Formation (34.25”) on Atwood
Cooling Unit’s Evaporator
13
4.7 Energy Usage Test Results
In addition to the tests which involved taking temperatures, the two 6 cu. ft. model
refrigerators (HE-0601 & DM2652) were monitored using a P3 International P4460 Kill A
Watt EZ Electricity Usage Monitor to determine the approximate power usage of each unit.
Both units were tested while within the test enclosure. The HE-0601 model had its
thermostat control at set point 4 while the DM2652 model was running on its automatic
thermostat. The energy usage was monitored for over a week and then the results were
extrapolated to determine the average usage in a month’s time. The HE-0601 model used
less energy during the test saving over four (4) kilo-watt hours (KWH) in the tested time
period which when extrapolated for a month is over fourteen kilo-watt hours (14 KWH).
The national average cost per KWH ($0.1196) was used to determine the cost of operating
each model over a period of time. Both refrigerators maintained comparable temperatures
at these settings.
Energy Cost Comparison
$25.00
$22.39
$20.67
$20.00
$15.00
$10.00
$4.82
$5.22
$5.00
$0.00
Cost/Week
Cost/Month
HE-0601
DM2652
P3 International P4460 Kill
A Watt EZ Electricity Usage
Monitor
© 2012 Ford’s RV Training & Service
14
5.0 Conclusions
The performance of the refrigerators was well within the parameters of the standard ANSI
Z21.19. Placing both the Atwood and Dometic refrigerators in adverse situations even more
severe than those called for in the standard did not greatly affect the refrigerators. Both
manufacturers’ models performed better than required. The Atwood and Dometic models
performed similarly in almost every phase. There were differences with the Dometic models
averaging lower temperatures in most cases and the Atwood averaging lower energy usage
and a lower temperature in the test enclosure. But the differences seen should not cause the
consumer or the RV industry concern as all models maintained adequate temperatures
during the testing. One concern that should be noted is the inability of the Atwood models
to restart operation after a power outage. As many consumers know, a loss of power can
happen due to a loss of shore power or faulty batteries among other things and this could
potentially cause food spoilage. The bottom line is that the helium absorption refrigerator
provides adequate refrigeration and performs well relative to the hydrogen absorption
refrigerator.
About Ford’s RV Training & Service
Ford’s RV Training & Service (Ford’s RV) has over 34 years experience in the RV industry.
Roger and Onna Lee Ford, who are the owners of Ford’s RV, are pioneers in the RV
refrigerator reconditioning industry having designed and still manufacturing the
customized tools required to recondition RV refrigerator cooling units. In addition, they
founded and oversee the only training center offering certification in the RV refrigerator
reconditioning field. Ford’s RV has set the standard in this field for 28 years by providing a
100 percent warranty for reconditioned RV refrigerator cooling units. Ford’s RV is the home
office and founder of the RV Referral Network (RVRN). Roger and Onna Lee Ford wrote the
first and only manual on reconditioning RV refrigerator cooling units The Ford Procedures
as well as the first and only troubleshooting and repair guide devoted strictly to RV
refrigerators called Average Joe’s RV Refrigerator Troubleshooting & Repair Guide. As
accomplished writers having written and published two publications previously, Roger and
Onna Lee’s expertise and ability to convey that expertise make them and Ford’s RV uniquely
qualified to complete this evaluation
The side by side evaluation of Atwood and Dometic refrigerators will continue for years to
come with updated reports created periodically. In addition, Ford’s RV plans to complete
evaluations on all the other RV appliances as well.
The preceding evaluation is copyrighted material and any disclosure, copying, or
distribution without written consent from Ford’s RV Training & Service is strictly
prohibited.
© 2012 Ford’s RV Training & Service
15
Terms of Usage
This document is provided to help you understand whether a given product merits
additional investigation for your particular needs. Any decision to purchase a product must
be based on your own assessment of suitability based on your needs. This evaluation was
focused on illustrating specific features and/or performance of the product(s) and was
conducted under controlled, laboratory conditions. Certain tests may have been tailored to
reflect performance under various conditions; however, performance may vary under other
conditions. Users should run tests based on their own scenarios to validate performance for
their uses.
Reasonable efforts were made to ensure the accuracy of the data contained herein but
errors and/or oversights can occur. The tests documented herein may also rely on various
test tools the accuracy of which is beyond our control. Furthermore, the document relies on
certain representations by the product manufacturer that are beyond our control to verify.
Among these is that the product tested is production grade and is available in equivalent or
better form to customers. Accordingly, this document is provided “as is”, and Ford’s RV
Training & Service (Ford’s RV) gives no warranty, representation or undertaking, whether
expressed or implied, and accepts no legal responsibility, whether direct or indirect, for the
accuracy, completeness, usefulness or suitability of any information contained herein. By
reviewing this document, you agree that your use of any information contained herein is at
your own risk, and you accept all risks and responsibility for losses, damages, costs and
other consequences resulting directly or indirectly from any information or material
available on it. Ford’s RV is not responsible for, and you agree to hold Ford’s RV and its
related affiliates harmless from any loss, harm, injury or damage resulting from or arising
out of your use of or reliance on any of the information provided herein.
Ford’s RV makes no claim as to whether any product or company described herein is
suitable for investment. You should obtain your own independent professional advice,
whether legal or otherwise, before proceeding with any investment or project related to any
information, products or companies described herein. When foreign translations exist, the
English document is considered authoritative. No part of any document may be reproduced,
in whole or in part, without the specific written permission of Ford’s RV Training & Service.
All trademarks used in the document are the property of their respected owners. You agree
not to use any trademark in or as the whole or part of your own trademarks in connection
with any activities, products or services or in a manner which may be confusing, misleading
or deceptive or in a manner that disparages us or our information, projects or
developments.
© 2012 Ford’s RV Training & Service
16