Replacement Fridge in 23d (CB)

[pcskier]

As noted in my other thread a few moments ago, I think my Dometic RM 2551 2-way fridge in my 2014 23d might have given up the ghost.

If it turns out I need to replace it, are there any other 2-way models such as Norcold that would be a direct replacement? It seems like RM 2551s are hard to find at this point, dometic has them on their website for $1,700 which is insane, but none of the usual suppliers like Dyers or PPL seem to show having them on their list. A couple of slightly sketch looking website retailers have them for about $1,000, but I haven't ascertained that those are credible vendors.

Additionally, I thinking maybe of switching to a compressor type, which is fine since I'm on shore power all winter, and all summer...just off-grid for some occasional trips in the spring/summer; but doing so would lead to me finally upgrading my solar install to include 400 ah of Lithium batteries, which was always on my radar at some point anyway. I'm a pretty conservative user of power when boondocking, and the two Trojan T-105s I have, combined with my 400w of solar, has been more than enough here in the west. But going to a compressor fridge would push me to Lithiums for sure.

So the question is...anyone know of a compressor fridge that is a pretty easy drop-in to replace a dometic 5 cu foot in a 23d? I think a few people have done it, but I can't recall how much modification was needed to trim out the cabinetery to mount it?

Any feedback on this would be appreciated!

[richard5933]

Is the fridge otherwise in good condition? If so contact JC Refrigeration - they have replacement cooling units for much less than a new fridge, with either LP or 12vdc compressor options.

[pcskier]

Originally Posted by richard5933

Is the fridge otherwise in good condition? If so contact JC Refrigeration - they have replacement cooling units for much less than a new fridge, with either LP or 12vdc compressor options.

Fridge is like new otherwise. I'm super disappointed. I've checked their website and it does not appear they have a cooling unit for my model, but I have emailed them to be sure. Thanks for the referral.

[richard5933]

Check with rvcoolingunit.com

This is where I bought the replacement cooling unit for my Airstream. Installed it myself in a day.

[Pimms]

We went through this in May of 21 when we fried the cooling unit in our 23fb by running it overnight off-level. After looking into every possibility I could find I finally bit the bullet and replaced with a Dometic RM 2554. It fit the opening perfectly and has the added bonus of three way cooling which will allow us to keep the fridge on while running down the road. We have 400W solar on the roof so the amp draw shouldn't be a problem. Yes, it was $1700 and the dealer said I was lucky to get one since at that time r/v replacement items were in such high demand. It was an expensive lesson to learn. You don't have to worry so much about leveling a compressor fridge but I could not find an exact fit and wanted to keep the propane option.

[guskmg]

Try Wick at Dometic Refrigerator Rebuild.
rvcool.com
1-800-515-6823
He will rebuild your refer with all new cooling parts at his place or send your unit to him UPS and he will rebuild it and send it back. His work is top notch and he had a zero comeback rate when he did mine 6 years ago. I think it cost $650 for the R&R at his place.
guskmg

[GlasairIIS]

Ultimately, I decided not to simply replace the cooling unit on my RM2551. My thought process was that the fridge was 10-years old which meant all the seals and the board were getting tired. I ordered new from a local RV parts supplier in Baton Rouge for $1600 plus tax and delivery fees. I’m in the process of swapping out the fridge now. Decided to build a proper plenum chamber to duct cool air across the condenser coil and out the vent with four fans. By the way, the new RM2551 I ordered is an updated version and came with a fan already attached to the upper tubes to help draw air upward. If you really take a close look at the Dometic installation instructions, you’ll quickly realize that Airstream doesn’t really abide by their installation details. Follow the manual and I feel certain that you’ll have excellent cooling results. I’ll know shortly……

[field & stream]

Originally Posted by GlasairIIS

Ultimately, I decided not to simply replace the cooling unit on my RM2551. My thought process was that the fridge was 10-years old which meant all the seals and the board were getting tired. I ordered new from a local RV parts supplier in Baton Rouge for $1600 plus tax and delivery fees. I’m in the process of swapping out the fridge now. Decided to build a proper plenum chamber to duct cool air across the condenser coil and out the vent with four fans. By the way, the new RM2551 I ordered is an updated version and came with a fan already attached to the upper tubes to help draw air upward. If you really take a close look at the Dometic installation instructions, you’ll quickly realize that Airstream doesn’t really abide by their installation details. Follow the manual and I feel certain that you’ll have excellent cooling results. I’ll know shortly……

Last year I rejected the idea of replacing my failing Dometic 2351 with a compressor fridge (because we camp unplugged almost exclusively) and bought a new 2351. My research showed what you have seen: Airstream violates virtually every installation design rule. No wonder they perform so poorly and fail frequently. I remodeled the fridge compartment to meet the Dometic specs and it is working great. Best wishes for your project.

[pcskier]

Originally Posted by field & stream

Last year I rejected the idea of replacing my failing Dometic 2351 with a compressor fridge (because we camp unplugged almost exclusively) and bought a new 2351. My research showed what you have seen: Airstream violates virtually every installation design rule. No wonder they perform so poorly and fail frequently. I remodeled the fridge compartment to meet the Dometic specs and it is working great. Best wishes for your project.

But they want us to believe they can produce an EV trailer. That’s laughable!

[Rltports]

Originally Posted by field & stream

Last year I rejected the idea of replacing my failing Dometic 2351 with a compressor fridge (because we camp unplugged almost exclusively) and bought a new 2351. My research showed what you have seen: Airstream violates virtually every installation design rule. No wonder they perform so poorly and fail frequently. I remodeled the fridge compartment to meet the Dometic specs and it is working great. Best wishes for your project.

Some details or pics of what you mean by “remodeled the fridge compartment” would be of interest. I am having issues with my unit and beginning to think about my next steps.

[CruizinDux]

I'm in too and have been working on some flashing deflector mods and another lower horizontal fan referenced above to go with the two sileniX at the top of the opening.


A trip last fall I experienced a very warm refer cabinet top and it turns out the stat failed or the connector crimp was bad. I replaced it OTR but realized I had no insulation per instructions above the refer and without the fans pulling the air out it settled above the refer. I too may be guilty of a slightly level situation in the driveway the night before the trip...close but not spot on.


I should also say I am changing stats from the OEM

I'm hopefully installing the 3rd fan this weekend and will post so images then. Note this fan will be powered by the hot lead at the refer and on a separate switch and thermostat. Both fan systems will also utilize a lower set point to turn on earlier and shut off later.


OEM 105/90 (on/off) and new 90/70 from Senasys. Note there are surface mounts and ambient air mounts. the fins are surface and the lower horizontal is ambient.

[field & stream]

Originally Posted by Rltports

Some details or pics of what you mean by “remodeled the fridge compartment” would be of interest. I am having issues with my unit and beginning to think about my next steps.

The remodeling had to do with airflow: 1) eliminating dead air space around the fridge, and 2) directing the cooler outside air over the coils and back outside.

1) Dometic calls for 1/4” or less above and besides the unit. My 16’ trailer had an inch above, 2” on one side, and 4” on the other! This allowed hot air to sit above the fridge and to recirculate down the sides from where it could rise again and reheat the coils. I added rigid insulation to eliminate these gaps (because I was a bit concerned about fire, I used expensive ceramic fiber insulation).

2) The most fundamental airflow design error can’t be fixed; on my model there is no chimney to allow the hot air to naturally rise and leave the compartment. Making that worse, the side exhaust vent is not even located above the coils, so the hot air has to make a 90 degree turn to exit the side of the trailer. Making that worse, there is a 1” lip at the top of the Airstream designed compartment that interferes with that turn and sideways flow. I installed a wedge of insulation up there to smooth the airflow.

Finally, the common problem with noisy and inefficient fan(s) needs to be addressed. I installed two quiet computer fans controlled by a thermostat.

In terms of refrigeration, this will not make an absorption fridge outperform an electric only compressor fridge — it will still struggle above 90 degrees. But that is easy to deal with by adding ice to the compartment and free compared to the many thousands of dollars required to power an electric only fridge unplugged.

[Rltports]

Originally Posted by field & stream

The remodeling had to do with airflow: 1) eliminating dead air space around the fridge, and 2) directing the cooler outside air over the coils and back outside.



1) Dometic calls for 1/4” or less above and besides the unit. My 16’ trailer had an inch above, 2” on one side, and 4” on the other! This allowed hot air to sit above the fridge and to recirculate down the sides from where it could rise again and reheat the coils. I added rigid insulation to eliminate these gaps (because I was a bit concerned about fire, I used expensive ceramic fiber insulation).



2) The most fundamental airflow design error can’t be fixed; on my model there is no chimney to allow the hot air to naturally rise and leave the compartment. Making that worse, the side exhaust vent is not even located above the coils, so the hot air has to make a 90 degree turn to exit the side of the trailer. Making that worse, there is a 1” lip at the top of the Airstream designed compartment that interferes with that turn and sideways flow. I installed a wedge of insulation up there to smooth the airflow.



Finally, the common problem with noisy and inefficient fan(s) needs to be addressed. I installed two quiet computer fans controlled by a thermostat.



In terms of refrigeration, this will not make an absorption fridge outperform an electric only compressor fridge — it will still struggle above 90 degrees. But that is easy to deal with by adding ice to the compartment and free compared to the many thousands of dollars required to power an electric only fridge unplugged.

Thank you. I just started a new thread as I’m beginning to think my unit is on its last legs. Great input and thanks again for the response.

[CruizinDux]

Originally Posted by field & stream

The remodeling had to do with airflow: 1) eliminating dead air space around the fridge, and 2) directing the cooler outside air over the coils and back outside.

1) Dometic calls for 1/4” or less above and besides the unit. My 16’ trailer had an inch above, 2” on one side, and 4” on the other! This allowed hot air to sit above the fridge and to recirculate down the sides from where it could rise again and reheat the coils. I added rigid insulation to eliminate these gaps (because I was a bit concerned about fire, I used expensive ceramic fiber insulation).

2) The most fundamental airflow design error can’t be fixed; on my model there is no chimney to allow the hot air to naturally rise and leave the compartment. Making that worse, the side exhaust vent is not even located above the coils, so the hot air has to make a 90 degree turn to exit the side of the trailer. Making that worse, there is a 1” lip at the top of the Airstream designed compartment that interferes with that turn and sideways flow. I installed a wedge of insulation up there to smooth the airflow.

Finally, the common problem with noisy and inefficient fan(s) needs to be addressed. I installed two quiet computer fans controlled by a thermostat.

In terms of refrigeration, this will not make an absorption fridge outperform an electric only compressor fridge — it will still struggle above 90 degrees. But that is easy to deal with by adding ice to the compartment and free compared to the many thousands of dollars required to power an electric only fridge unplugged.

Hate to say I was lucky but my side clearance was none to an 1/8" and called it good. I too had about 2" on top.

Here are some pics. I thought about some quality insulation up top but simply had no clearance to insert it. I basically cut some very thin sheet and notched them to fit and slipped them up (one by one) behind the cooling fins with the 2 pieces mated at the center. They cover all of the opening Left to Right (notched for the power cored and 1x blocking) and from the top of the interior cabinet to about 1" below the cooling fins. A small SM screw thru the bracing keeps them in place.


Not the perfect solution but I'm not really interested in removing the refer aside from the fact the location of the condenser fins in relation to the top door edge is done! However I have a 2' section of galv duct that I may cut a long section out of and possibly slip over the top to give a better flow than the existing rectangular cabinet.


I've attach a smaller horizontal fan to another 6x so it will lay flat just above the lower coil section.

I'll pull power separately from the std lighted fan switch inside to control the two upper fans as I wanted to be able to run the top tow one one state and/or the bottom one on another stat.

I bought a remote digital thermo at WM that has two sensors. I'll put one in the refer and the other in the exterior compartment..,maybe move it around to get an idea of how temp and the various fan combinations affects interior temp. I also have crimped up a couple of spade jumpers in case I want to bypass the stats and just let the fans run. I also left the OEM stat on the fins not connected in case I want to revert back.

I also removed the springs that the fans were originally suspended from and used some zip ties as I wanted to get the fans as high to the top edge as I could. I'll also get some fire caulk to seal the sheets up a bit. Probably overkill but suspect the builder next door will have a partial tube.



Hoping for a long enough trip so I can experiment with settings over a period of time.

[field & stream]

CruizinDux — Looks great, that will certainly perform better.

[CruizinDux]

Field & Stream, thanks. Need to wrap this up and move onto some otr time.

Happy trials

[CruizinDux]

to finish things, I dropped in the horizontal fan yesterday and wired from the 12V refer connection including a fuse, toggle switch for control. Kinda noisy, but then it was a $0.50 grab at the recycle center in Eug. I figured I'd swap it out with a SileniX if it works.



It will be interesting to see performance as both the upper and lower fans are on their separate switch and stats (85/70 ~ quoted as 90/75) to replace the old (100/85 +/-5°) generally quoted as 105/90. The start earlier and turn off later but heck, they're designed to run 100%. I have the jumper wire hanging there so if needed control by switch only if needed.


http://silenx.com/quiet.fans.asp?sku=efx-08-15 need to measure to see if the 09-15 with a bit more push will fit in consideration of the diverter flashing

[GlasairIIS]

A few photos of my recent install of a replacement Dometic fridge in my 23d. This baffel installation appears to pretty much meet Dometic’s installation instructions for side vent and wasn’t overly complex. This configuration resulted in good suction thru the lower vents and out the top. All of the air coming in the bottom has no choice but to pass across the tubing and thru the heat exchanger. It’s still cool her in Louisiana,,, but summer is on its way. It will be thoroughly tested, that’s for sure! 😆

[CruizinDux]

GlasairIIS, nice install for sure. nice to have plenty of room to work. I've thought about some additional deflectors or like what you did to simply leave openings at the fan. That means running the fans all the time as opposed to natural heat rises air flow, but maybe that's the optimal design. Thanks for your pics.

[pcskier]

I should update my original post that started this thread. My fridge and freezer were completely dead, temperature-wise. Room temperature in both. The boiler was still operating on propane or electric, and there were no signs of leaks in the cooling system.

After a day and a half of research and resigning myself to buying a new cooling unit, and dreading removing the fridge in the middle of winter to change it out...while I'm living in the darn thing...I turned off the fridge for the night.

Lo and behold, just for grins I turned it on the next morning, and within hours was back to normal. I believe that my ammonia solution has some crystals formed in it, which built up most likely at the top of the tube coming from the boiler, where it makes a 90 degree turn...completely stopping the flow of solution.

By turning off the fridge and therefore the boiler, the solution cooled and stopped trying to push through the system...and the crystals settled out and the system unclogged.

Now I keep a remote thermo in the fridge, and it's sitting at 33.6 degrees two months later. I did have one instance where it happened again...turned off the unit for 5-6 hours (less probably would have worked) and also tapped on the cooling unit piping at that 90 degree bend to help loosen up any clogs. Turned it back on, all back to normal.

Now, I keep an eye on the temp and if I see it starting to rise, I'll turn off the fridge for an hour or two.

I'm probably on borrowed time but I found some resources where people have said that they were fine years later.

I also, btw, will be turning it off when climbing long grades, sitting on an unlevel roadside for lunch, etc...being unlevel is a major cause of the boiler overheating and causing the crystals to form.