Dometic vs Isotherm

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johnr9q

Member
Joined
Sep 27, 2016
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15
Location
United States
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.
 
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.
 
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.

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 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 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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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.
 
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
 
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.
 
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.
 
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.
 
John,

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

Tom
 
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.
 
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. :facepalm:

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.
 
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. :facepalm:

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.
 
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. :facepalm:

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.
 
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.
 
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.
 
We have a brand new isotherm cr130 and have the exact same problem. Did the fans help?
 
I got rid of my 2 way Norcold a few months ago and replaced with a Whirlpool / added external inverter for dc use. What an improvement! Norcold replacement $1,500. Whirlpool hecho in Mexico $300.

add insulation and air circulation to compressor if you want to improve performance. I have a solar powered fan to help air circulation.
 
I got rid of my 2 way Norcold a few months ago and replaced with a Whirlpool / added external inverter for dc use. What an improvement! Norcold replacement $1,500. Whirlpool hecho in Mexico $300.

add insulation and air circulation to compressor if you want to improve performance. I have a solar powered fan to help air circulation.

Totally agree.
12 volt refrigeration is crazy money and seriously lacking.
Far better using decent inverter and cheap, reliable house style fridge freezer, especially if living aboard and wanting comforts vs camping.
 
If you can fit a cheapo fridge....and only seriously lacking if you want auto defrost. Otherwise they refrigerate and freeze just like any other household fridge.

I wish I could have but because the boat is my home, and I didn't feel like losing cabinet space or doing a weeks worth of woodworking .....

I spent the money on a vitrifrigo and am perfectly content despite the $1000 difference...and for me...it's a big deal.
 
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We have a brand new isotherm cr130 and have the exact same problem. Did the fans help?

Reread what I previously posted:

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.
 
Looks like we will return the isotherm and change to a dometic. We lose almost a cubic foot of space for the same footprint but I need refrigeration. West Marine will swap this out for us and the new unit will be in a few days.

We cruise and spend weeks at a time at anchor so an electric fridge is not an option.
 
Looks like we will return the isotherm and change to a dometic. We lose almost a cubic foot of space for the same footprint but I need refrigeration. West Marine will swap this out for us and the new unit will be in a few days.

We cruise and spend weeks at a time at anchor so an electric fridge is not an option.

Steve and Janice: Why don't you place the Isotherm in a 90 degree room and let it run on max setting for 12 hours and see how cold it gets. Put some water in the unit to simulate loading it. It may be that the unit I have is an anomaly and yours will work just fine. It would do the entire boating community a big favor if you did this. It's very easy to do this, just uncrate it and plug it into 120 volts with the cord provided. No need to hook it up to 12 volts. I asked a previous responder to do this but got no response.
 
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We have been using the fridge for several weeks. We exchanged it for a new one 2 weeks ago and this one acts the same.

Setting is at coldest. Freezer is cold, single digits to low teens depending on the weather. Fridge varies from around 47 to 52 at 80 degrees. We are currently in Ft Meyers area and it was cold last night so the fridge was at 32 this morning. It is 74 right now and fridge is 41.
 
Totally agree.
12 volt refrigeration is crazy money and seriously lacking.
Far better using decent inverter and cheap, reliable house style fridge freezer, especially if living aboard and wanting comforts vs camping.

This is not brain surgery . A BTU is a BTU is a BTU. If you have a box thats is letting X amount of heat in it rated in BTUs you have to get it out ! So if you have a huge battery bank or massive amount of solar or are not to concerned about running a generator, then a home fridge will probably work for you . Of course I am talking about of grid or on the hook , who cares when you are on shore power .
You must remember that as the ambient temperatures around your home fridge increases your efficiency of your home fridge goes down , These systems are designed to be used in a home were the ambient temperature fluctuate very little . So a home fridge in a non air conditioned boat in the tropics is going to be a energy hog , actually it may not even work at all with all the power in the world . This is were a 12v system shines . But the box you put it in is as critical as the unit you choose to install . This is a very long conversation but let me just say that most 12v conversion systems work the same way a store bought home fridge does, therefore suffer from the same critical temperatures of the environment they are put in . The only system that performs better then the rest in the tropics is one that uses a thermostatic valve to control refrigerant . These systems can use a massively sized condenser and have a better time condensing in a hot climate . They are also not as sensitive to condensing temperatures.

Basically done right in the right box, refrigeration will be the least troublesome system on your boat , and use very little in the way of power

An 8 cubic foot fridge in the tropics should not use not more then 26 amp hours at 12v volts . Of course this has to be top loading box and not be opened a 100 times a day LOL


Regards
Try that with a home fridge
 
a home fridge in a non air conditioned boat in the tropics is going to be a energy hog , actually it may not even work at all with all the power in the world . This is were a 12v system shines

Try that with a home fridge
Reality says something different for us.

I live in the tropics in a NON airconditioned boat and have had 32+ degree c days recently with a fridge near 16 cubic feet with icemaker and have no issues with power consumption.
Genset never gets used while the sun shines for half a day.

This fridge would cost about $1500 to replace and is easily available at any electrical retailer in the country and if it ever has issues will get dumped and replaced with a nice new version.
Current version has been in use for at least 10 years.

A comparable 12v would be a custom build and would likely cost more than 10x that amount.

Due to the 12v cost, if it had problems I would be forced to get a mobile refrigeration "expert" out and his fee for repair would probably be as much as a new 240v fridge.
 
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