Read an article concerning ammonia fridges and their relationship to ambient versus internal temperatures.The article stated that the temperature differential is around 30 degrees internal versus external and it seems to hold water in my testing.Been running my Dometic on shore power in the side yard (empty). I have adequate airflow over the upper condenser with the correct baffles and 2 120mm muffin fans pulling the air through the backside cavity from the lower intake out through the upper vent and 2 additional muffin fans inside the fridge circulating cold air inside. The fridge is well insulated, I added almost a full roll of unfaced R11 insulation around the entire fridge, between the fridge body and the outer cabinet so I'm as 'efficient' as I can get.I have a recording remote thermometer in the fridge with the readout outside and I've watched for about a week now and the interior temp averages about 30 degrees colder than ambient, more at night, closer to 50 dergrees differential than during the day when it drops back to around 30The article I read seems to be correct at around 30 degrees temperature differential.I think this winter, I'll be pulling the Dometic ammonia fridge and installing another Dometic C series Danfoss Compressor unit in it's place. I have a portable Dometic Cool box I carry in the truck and it has no issue holding whatever temperature I set it at from 30 degrees on up in the fridge section to minus 15 in the freezer section.

I'll see if I can verify your numbers today as it will be pretty hot here. 2018 08 09Please let us know how the swap to Dometic Danfoss goes. Prices would be nice to have.Do you still have a link to the article?

I'm guessing that's 30C (54F), and for the refrigerator section, not the freezer. A 30F differential would mean a 60F fridge when it's 90F outside. And even that seems low. Ours does way better than that.

My Dometic stays sufficiently cold all the time. When it's over 90 outside and my a/c can barely maintain 80, the refer is having no problem.

Funny.......My Dometic RM2862 has been able to hold 5*F/Freezer and 38*F-40*F/Food compartment regardless of outside temps. (been in 110*F temps and in high humidity) And it doesn't even have fans.Course it was properly installed with less then 1" rear clearance, 0" clearances top/sides, NO dead air spaces and really good natural draft via roof ventDid have cooling issues couple times when we were in 0*F and lower outside temps (winter storm/snow) but that was easily resolved with the use of a 60W light bulb in lower section of outside compartment

Our Dometic must have been installed properly as it will stay about 50 degrees cooler than outside temps. Usually it will be about 40 degrees when the outside temp is 90+.

Ammonia Fridges, read an interesting piece a while ago

pianotuna
Nomad III
Aug 09, 2018
I'll see if I can verify your numbers today as it will be pretty hot here. 2018 08 09

Please let us know how the swap to Dometic Danfoss goes. Prices would be nice to have.

Do you still have a link to the article?
mike-s
Explorer
Aug 09, 2018
I'm guessing that's 30C (54F), and for the refrigerator section, not the freezer. A 30F differential would mean a 60F fridge when it's 90F outside. And even that seems low. Ours does way better than that.
2oldman
Explorer II
Aug 09, 2018
My Dometic stays sufficiently cold all the time. When it's over 90 outside and my a/c can barely maintain 80, the refer is having no problem.
Old-Biscuit
Explorer III
Aug 09, 2018
Funny.......

My Dometic RM2862 has been able to hold 5*F/Freezer and 38*F-40*F/Food compartment regardless of outside temps. (been in 110*F temps and in high humidity)
And it doesn't even have fans.
Course it was properly installed with less then 1" rear clearance, 0" clearances top/sides, NO dead air spaces and really good natural draft via roof vent

Did have cooling issues couple times when we were in 0*F and lower outside temps (winter storm/snow) but that was easily resolved with the use of a 60W light bulb in lower section of outside compartment
hotjag1
Explorer II
Aug 09, 2018
Our Dometic must have been installed properly as it will stay about 50 degrees cooler than outside temps. Usually it will be about 40 degrees when the outside temp is 90+.
SidecarFlip
Explorer III
Aug 09, 2018
pianotuna wrote:
I'll see if I can verify your numbers today as it will be pretty hot here. 2018 08 09

Please let us know how the swap to Dometic Danfoss goes. Prices would be nice to have.

Do you still have a link to the article?

No, I don't but it was an offshoot article from Truck Camper Adventurers. I read lots of forums but belong to very few.

I have priced a comparable Dometic C series Danfoss / Seacop compressor fridge (same cutout size as the ammonia one I have) and it was about 800 bucks on a internet marine supply website.

One thing about a Danfoss Secop unit is you eliminate the propane feed entirely and they are self contained, that is, the refrigeration unit is pre mounted to the fridge itself and most all of them are 12 volt, 24 volt and 120 volt so you can do shore power or house battery power.

You can also get them with remote refrigeration systems so you can mount the compressor and evaporator remotely from the fridge itself.
Community Alumni
Aug 09, 2018
My Norcold 2118S was working flawlessly. Then 2 months ago, the temps climbed to 60 in the fridge and 28 in the freezer. I set up a visit with a NORCOLD CERTIFIED technician recommended by NORCOLD. The technician stated it was a bad cooling unit. Norcold has since recommended that the technician come back out for minor things before they will send their own technician a cooling unit to install. Each visit is $175 out of my own pocket due to the mobile tech charge. The reason the mobile charge is that high is they are the closest to my at 2 1/2 hours away. Norcold units may be good but their customer service UNDER WARRANTY sucks. I have decided to scrap their crappy fridge and change to a residential. Norcold can go to #$%^!!!

Note that my RV and fridge are under warranty and are only 6 months old.
dougrainer
Nomad
Aug 09, 2018
Sorry, but there is No Relationship between external temps and interior refer temps. THAT SAID. If you park a RV in 100 degree heat and have NO AC cooling the inside and have the refer ON, odds are it will not cool to spec. Same thing with a residential refer. Put that residential in a hot barn or garage and expect the residential to keep things cold will be hard to do. My residential in my old house in the garage in 90 plus heat had a hard time keeping things below 45 degrees. When I moved and was able to put the same refer in a utility room that had AC, it would get below 35 consistently and still does after 34 years. But, there is NO Temp Differential measurement like a AC temp Diff measurement for a RV refer. Using your logic, the only way the RV refer would get below 40 degrees was if the outside was 70 degrees or colder. In Texas 100 degree heat, I get RV refers to 32 to 34 degrees all the time in Customer testing. I ALWAYS have the AC ON to keep the interior below 80 degrees. Doug
dougrainer
Nomad
Aug 09, 2018
chag67 wrote:
My Norcold 2118S was working flawlessly. Then 2 months ago, the temps climbed to 60 in the fridge and 28 in the freezer. I set up a visit with a NORCOLD CERTIFIED technician recommended by NORCOLD. The technician stated it was a bad cooling unit. Norcold has since recommended that the technician come back out for minor things before they will send their own technician a cooling unit to install. Each visit is $175 out of my own pocket due to the mobile tech charge. The reason the mobile charge is that high is they are the closest to my at 2 1/2 hours away. Norcold units may be good but their customer service UNDER WARRANTY sucks. I have decided to scrap their crappy fridge and change to a residential. Norcold can go to #$%^!!!

Note that my RV and fridge are under warranty and are only 6 months old.

While you have a Warranty, YOU must make arrangements to get that Norcold to a Service Center. The fact YOU hired a Mobile Tech is NOT Norcold's fault. YOU chose to live 2 1/2 hours away. That is NOT Norcold's fault. These are MOBILE RV's and you need to get the RV into the Service Center for the best result and repair. Doug
ktmrfs
Explorer II
Aug 09, 2018
My experience is that our dometic will keep the fridge at "normal" temps even when outside temps are near 100F and the trailer is sitting in the sun w/o AC on.

A few weeks ago outside temps where in the high 90's. No power for AC, left the trailer all day, came back fridge was 10F in the freezer, 40F in fridge, trailer temp in the upper 90's.