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Old 09-27-2016, 02:38 PM   #1
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Dometic vs Isotherm

I have a Dometic (Waeco) CoolMatic CR-1110 Refrigerator in my cabover truck camper. This refrigerator is a compressor style refrigerator. I was concerned that the compressor was running too long in warmer temperatures to keep the fridge at a reasonable temperature (40 degrees).
I have a friend that has an Isotherm Cruise CR 130 compressor style refrigerator Installed in a Sprinter van. I thought doing a comparison between the two would tell me how my Dometic stacked up with the Isotherm.
Comparing both refrigerators:
1. They both have a Danfoss BD35F compressor.
2. The Isotherm is a little larger at 4.6 cubic foot and the Dometic is 3.8 cubic foot.
3. The Dometic is 6 months old and the Isotherm is 4 years old.
4. The way the Isotherm is designed the condenser coils are in closer proximity to the compressor (which gives off a lot of heat) than the Dometic
5. There are more condenser coils on the Dometic.
6. When each refrigerator was running, they were drawing approximately 4 amps

To do the testing, I did the following to both refrigerators:
1. I put two, one gallon ziplock bags full of water in the refrigerator section and a one quart ziplock bag in the freezer section.
2. I ran both for 12 hours previous to gathering data.
3. I checked measurements on the compartments that the refrigerators were installed in and both exceeded the requirements provided by the manufacturer
Results:
The Dometic refrigerator interior temperature was, freezer section 13 degrees, refrigerator section 38 degrees. The outside ambient air temperature was 87 degrees. The compressor was cycling on and off and stayed on 31% of the time
The Isotherm refrigerator interior temperature was, freezer section 18 degrees, refrigerator section 53 degrees. The outside ambient air temperature was 90 degrees. The compressor was on 100% of the time.
To be fair I was concerned that the cabinet enclosures might be different between the Dometic and Isotherm and affect the operation of the refrigerators so I decided to remove the Isotherm from its cabinet and do the same test with it in unrestricted airflow. (I did not test the Dometic out of its cabinet) The refrigerator interior temperature was, freezer section 13 degrees, refrigerator section 36 degrees. The outside ambient air temperature was 92 degrees. The compressor was on 100% of the time.
Conclusion: The Dometic was a clear winner in my test. It only ran 1/3 of the time and maintained an internal refrigerator section temperature that was 15 degrees lower than the Isotherm. Even when the Isotherm was outside of its cabinet it could only maintain a similar temperature as the Dometic yet it ran over 3 times longer.
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Old 09-27-2016, 03:21 PM   #2
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And conclusion too that he needs to get someone to work on his Isotherm as it's no longer refrigerating. 53 degrees isn't a refrigerator.
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Old 09-27-2016, 03:43 PM   #3
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Welcome aboard.
What prompted you to do the testing?
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Old 09-27-2016, 03:54 PM   #4
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Welcome aboard.
What prompted you to do the testing?
Is an interesting first post. I think that makes your question very good.
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Old 09-27-2016, 04:16 PM   #5
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Welcome aboard.
What prompted you to do the testing?
As is said in the second sentence of my post, I was concerned that my Dometic wasn't working properly so thought a comparison would be insightful plus I'm OCD.
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Old 09-27-2016, 10:34 PM   #6
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As is said in the second sentence of my post, I was concerned that my Dometic wasn't working properly so thought a comparison would be insightful plus I'm OCD.
I'm sure you felt better after the test, but how did your friend take the news that his refrigerator wasn't working properly?
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Old 09-28-2016, 09:26 AM   #7
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I don't think you have proved that Dometic is better than Isotherm. But you have proved that the Isotherm is not working properly, maybe due to a leak and low Freon.


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Old 09-28-2016, 10:05 AM   #8
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I don't think you have proved that Dometic is better than Isotherm. But you have proved that the Isotherm is not working properly, maybe due to a leak and low Freon.


David
I worked with Isotherm to insure we were comparing apples to apples and one of the things I did was to check the freon level in the Isotherm and it was where it should be. I did point out that the Isotherm is older and also a little larger so this may account for some of the difference in performance but IMHO I think the Dometic is still the winner. You can draw your own conclusions. Isotherm did admit that maybe in hot temps their unit's performance will be reduced. (to me this is obvious with all refrigerators but you have to decide what performance is acceptable to you). As I concluded in my post, Isotherm's placement of the compressor and the condenser may account for its reduced performance. You make a good point that the Isotherm may be defective. Obviously my testing has a very small sample size (one) and this would certainly not be considered a gold standard test with that sample size. I am hoping there are others out there that will do a similar test so we can increase the sample size. As all they would need to do is not open the door during the test, have the unit running for at least 12 hours and note the internal refrigerator and the outside temperature.
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Old 09-28-2016, 10:07 AM   #9
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I'm sure you felt better after the test, but how did your friend take the news that his refrigerator wasn't working properly?
I installed 3 computer fans to circulate air better and hopefully this will improve the Isotherm performance. We are taking it on a trip in a week and I'll let you know if it works better.
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Old 09-28-2016, 11:00 AM   #10
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How did you check the Freon level. The only sure way on these small units is to completely evacuate all Freon and refill to the manufacturer's specified weight of Freon.


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Old 09-28-2016, 11:24 AM   #11
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Originally Posted by johnr9q View Post
I installed 3 computer fans to circulate air better and hopefully this will improve the Isotherm performance. We are taking it on a trip in a week and I'll let you know if it works better.
I'll be interested in your results. I was also wondering what test equipment you used to measure the on/off cycle of the compressors over the 12 hour period.
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Old 09-28-2016, 11:45 AM   #12
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How did you check the Freon level. The only sure way on these small units is to completely evacuate all Freon and refill to the manufacturer's specified weight of Freon.


David
David: I appreciate you challenging me as that is the way to get to the bottom of an issue. I worked with Isotherm and ordered a set of gauges. We did not evacuate the system as there was no evidence of a leak and the Freon was at the appropriate level. I did add a bit to bring it up to the maximum recommended but that didn't change any of the readings.
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Old 09-28-2016, 11:53 AM   #13
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I'll be interested in your results. I was also wondering what test equipment you used to measure the on/off cycle of the compressors over the 12 hour period.
I worked with Isotherm and they recommend I jumper the "C" and "T" terminals on the control board which makes the compressor run full time. On my Dometic, I installed an hour meter which keeps track of the time the unit runs. Thanks for your interest. Is this the best forum to post something like this? I don't have a boat but I believe sail boats (and maybe also motor boats) are more inclined to use compressor style refrigerators. Land campers usually use the type of Refrigerators that uses a flame. (possible reasons for that are boats are out of level a lot and flame type can't handle being out of level very well and also maybe Propane isn't as desirable on a boat?) I also posted my results on cruisersforum.com but don't get near the responses I get on this forum.
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Old 09-28-2016, 01:05 PM   #14
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John,

Where is the compressor and condenser on the model you tested?

Tom
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Old 09-28-2016, 03:47 PM   #15
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John,

Where is the compressor and condenser on the model you tested?

Tom
Both units the compressor/condenser are on the top rear. On the Dometic, it takes up the entire width of the rear, on the Isotherm, it takes up about 1/2 of the rear. The way Isotherm packaged the compressor/condenser it is more compact but, as I pointed out previously, I think the condenser is picking up too much heat from the compressor the way it is packaged.
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Old 09-28-2016, 11:30 PM   #16
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Quote:
Originally Posted by johnr9q View Post
I worked with Isotherm and they recommend I jumper the "C" and "T" terminals on the control board which makes the compressor run full time. On my Dometic, I installed an hour meter which keeps track of the time the unit runs. Thanks for your interest. Is this the best forum to post something like this? I don't have a boat but I believe sail boats (and maybe also motor boats) are more inclined to use compressor style refrigerators. Land campers usually use the type of Refrigerators that uses a flame. (possible reasons for that are boats are out of level a lot and flame type can't handle being out of level very well and also maybe Propane isn't as desirable on a boat?) I also posted my results on cruisersforum.com but don't get near the responses I get on this forum.
I'm personally interested in your test because I just purchased an Isotherm Cruise 195 Fridge/Freezer for my boat. I haven't installed it yet but if the fridge only gets down to 53 degrees, it's going back. I know this is selfish, but I hope that adding the fans to your friend's Isotherm doesn't help and that there is some type of malfunction that is not allowing it to cool properly. But on the other hand I think that even a failure after 4 years is premature. Sometimes you just can't win.

Some boaters do not like to use propane on a boat. Propane is heavier than air and therefore sinks to the bottom of the bilges in a boat and will accumulate and not dissipate as it could in an RV on the open road. However, a boat with a properly installed and maintained propane system with detectors and shutoff solenoids is acceptable to many boaters.

Thanks for posting.
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Old 09-29-2016, 09:03 AM   #17
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Quote:
Originally Posted by FOG View Post
I'm personally interested in your test because I just purchased an Isotherm Cruise 195 Fridge/Freezer for my boat. I haven't installed it yet but if the fridge only gets down to 53 degrees, it's going back. I know this is selfish, but I hope that adding the fans to your friend's Isotherm doesn't help and that there is some type of malfunction that is not allowing it to cool properly. But on the other hand I think that even a failure after 4 years is premature. Sometimes you just can't win.

Some boaters do not like to use propane on a boat. Propane is heavier than air and therefore sinks to the bottom of the bilges in a boat and will accumulate and not dissipate as it could in an RV on the open road. However, a boat with a properly installed and maintained propane system with detectors and shutoff solenoids is acceptable to many boaters.

Thanks for posting.
You must have a power boat if you considered Propane refrigeration? From what I understand, a sail boat doesn't stay level enough to handle a propane fridge? I'll let you know the results in a couple of weeks. However we are headed to Utah and considering it is getting cooler out now, the fridge may work just fine.
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Old 10-17-2016, 11:33 AM   #18
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Quote:
Originally Posted by FOG View Post
I'm personally interested in your test because I just purchased an Isotherm Cruise 195 Fridge/Freezer for my boat. I haven't installed it yet but if the fridge only gets down to 53 degrees, it's going back. I know this is selfish, but I hope that adding the fans to your friend's Isotherm doesn't help and that there is some type of malfunction that is not allowing it to cool properly. But on the other hand I think that even a failure after 4 years is premature. Sometimes you just can't win.

Some boaters do not like to use propane on a boat. Propane is heavier than air and therefore sinks to the bottom of the bilges in a boat and will accumulate and not dissipate as it could in an RV on the open road. However, a boat with a properly installed and maintained propane system with detectors and shutoff solenoids is acceptable to many boaters.

Thanks for posting.
Fog: We just got back from the trip to Utah and I wasn't impressed with the operation of the Isotherm. Even with the fans installed, at 80 degrees outside temperature, the fridge couldn't get below 48 degrees. I suggest, before you install your fridge, you take it out of the box and put it in a room that is 90 degrees, put some ziplocks with water in them, and see how the unit performs. Let me know the results.
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Old 10-21-2016, 12:54 PM   #19
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Fog: We just got back from the trip to Utah and I wasn't impressed with the operation of the Isotherm. Even with the fans installed, at 80 degrees outside temperature, the fridge couldn't get below 48 degrees. I suggest, before you install your fridge, you take it out of the box and put it in a room that is 90 degrees, put some ziplocks with water in them, and see how the unit performs. Let me know the results.
Good suggestion. However, I don't think I'm going to get any 90* days before I install it. But I'll test it and report back my results.
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Old 10-21-2016, 01:37 PM   #20
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Good suggestion. However, I don't think I'm going to get any 90* days before I install it. But I'll test it and report back my results.
He said "room that is 90 degrees." You can create one of those. Just turn the heat way up or use a space heater.
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