Dometic RM2551 fridge won't operate on propane

[kjmaggart]

We are new to the camping / RV world so please excuse any rookie statements I make. We love the camper but are learning there are a number of maintenance issues.

Our Dometic runs well on shore power. The bottom of the tube heats up and there's a noticable difference in temp between the top and bottom of the tube.

On LP, however, it lights with no problem and stays lit with a nice blue flame. However, the entire tube heats to the point of being very hot to the touch; no thermo difference between top and bottom.

The fridge does not cool at all when on LP. I've inspected the board and it looks good - no obvious overheating or bad connections. I've inspected the flume from the bottom. The baffle is present and I do not detect any soot or debris in the tube.

I appreciate any suggestions as to what to do next. I am mechanically inclined so not afraid to get into it deeper.

[DFord]

If it was me, I'd buy another orifice (I've been repairing furnaces since 1970). The hole size of that piece is critical. There must have been something partially blocking it. Wallowing out with a pin as you did could cause problems later. May as well benefit from an undamaged one while you own it. You wouldn't want to pass it on to a future owner in that condition (liability).

[kjmaggart]

Also, I want to thank everyone who has given advice. You guys are awesome! Many times the people in forums are not kind to someone new to the whatever.

Not the case here. Everyone had great suggestions and it felt like you really wanted to help. Thanks again! We're looking forward to our next trip next week!

[kjmaggart]

I looked at the pinhole orifice and could not see through. So, took a very small pin and widened a bit. Made all the difference in the world! I now have a flame that looks like the one Old Biscuit posted.

May have done a little too good a job because I had to reduce the amount of gas going through as it was a bit too good.

Now, the bottom of the flue is hot and the top is not!! Just like it's supposed to be.

Fingers crossed, we may have the issue resolved!

[ktmrfs]

Old-Biscuit wrote:

ktmrfs wrote:

kjmaggart wrote:
Ok; my flame doesn't look like that. It looks like the small, bright flames in the picture but doesn't create a plume of blue flame. Next thing is to check the pressure and make sure we are getting the propane necessary.

Thanks for an informative pic!

the orfice for the propane is very very small. easy for any spec if dust, spider web etc. to partially plug it. It happens, has been an issue for me on occasion. Solution is to remove the gas jet, clean it out with a welding tip cleaner of appropriate size and blow the tube out to get any dust, debris, rust etc out as well. and do the same around the flue. Then try again.

Dirty orifice would NOT allow that good of a flame.
Dirty orifice would disrupt gas flow which would NOT provide enough air mixture and flame would be very yellow

That flame is from LOW LP SYSTEM Pressure

I beg to differ since I have and a few others I know, flame very similar to the one the OP posted and inspecting and cleaning the orfice and the flame was back to normal. the "bad" flame was still blue, just very short. Now depending on how bad the orfice is plugged, yes it could very well be yellow. but a piece of spider web is all it takes to have an effect.

[Old-Biscuit]

ktmrfs wrote:

kjmaggart wrote:
Ok; my flame doesn't look like that. It looks like the small, bright flames in the picture but doesn't create a plume of blue flame. Next thing is to check the pressure and make sure we are getting the propane necessary.

Thanks for an informative pic!

the orfice for the propane is very very small. easy for any spec if dust, spider web etc. to partially plug it. It happens, has been an issue for me on occasion. Solution is to remove the gas jet, clean it out with a welding tip cleaner of appropriate size and blow the tube out to get any dust, debris, rust etc out as well. and do the same around the flue. Then try again.

Dirty orifice would NOT allow that good of a flame.
Dirty orifice would disrupt gas flow which would NOT provide enough air mixture and flame would be very yellow

That flame is from LOW LP SYSTEM Pressure

[ktmrfs]

kjmaggart wrote:
Ok; my flame doesn't look like that. It looks like the small, bright flames in the picture but doesn't create a plume of blue flame. Next thing is to check the pressure and make sure we are getting the propane necessary.

Thanks for an informative pic!

the orfice for the propane is very very small. easy for any spec if dust, spider web etc. to partially plug it. It happens, has been an issue for me on occasion. Solution is to remove the gas jet, clean it out with a welding tip cleaner of appropriate size and blow the tube out to get any dust, debris, rust etc out as well. and do the same around the flue. Then try again.

[dougrainer]

kjmaggart wrote:
I took a gun cleaning brush and cleaned out the tube. I went all the way past the holes. There was no debris. My next task is to check the pressure. Both stove units burn bright blue with plenty of flame. So, I believe the problem would have to be after the split to the stove.

Also,as a footnote, the water heater works very well. Only 20-30 minutes after turning on that we have nice, hot water.

You need to pull the refer and remove the spiral baffle and then clean the flue tube. 11.5 inches WC is the LP pressure. Your stove operates at 10 inches WC. It has its own regulator that drops the LP pressure. The water heater also will operate with lower than spec LP pressure. Just a drop from 11.5 to 10 inches will affect the LP flame on the refer. Doug

[kjmaggart]

I took a gun cleaning brush and cleaned out the tube. I went all the way past the holes. There was no debris. My next task is to check the pressure. Both stove units burn bright blue with plenty of flame. So, I believe the problem would have to be after the split to the stove.

Also,as a footnote, the water heater works very well. Only 20-30 minutes after turning on that we have nice, hot water.

[DFord]

kjmaggart,
I managed to get a link to your picture:


You're right, not much flame there. If the pressure is correct (11 inches of water column) check for a spider nest in the orifice.

[kjmaggart]

So this is how my flame appears:
https://www.flickr.com/photos/137198858@N05/48737539913/in/dateposted/

I have completed a leak test and can find no leaks. The burners on the stove put off a much higher flame - exactly what I would expect from a gas stove.

[kjmaggart]

Ok; my flame doesn't look like that. It looks like the small, bright flames in the picture but doesn't create a plume of blue flame. Next thing is to check the pressure and make sure we are getting the propane necessary.

Thanks for an informative pic!

[Old-Biscuit]

Flame should be strong BLUE and reach just inside the flue




Remove burner assembly
Clean burner tube/slots
Clean orifice (soak in alcohol...then air dry
(***NO POKING anything thru OR High Pressure Air)

If flame still small.....
LP System Pressure S/B 11"WC with at least 50% of other propane appliances in service
Test port on fridge gas valve for connecting Manometer

[kjmaggart]

Thanks so much everyone! Especially love the diagram on how the unit works. Excellent information. The camper is a 2013 Vista. The Mfg date on the Dometic RM2551 is 2011.

I have not pulled out the unit and inspected from the top down which is my next task. I did try to push the baffle upwards to see if there was any resistance which it wouldn't move.

The flame does not reach the inside of the flue. It is a small blue flame that is about 1/4 to 1/2 inch high.

[dougrainer]

You did good research. I doubt 1 out of 10,000 RV'ers would even know to inspect the Baffle to be there. IF they even knew they had one. The critical point since you seem to have done almost everything. EXCEPT-The LP pressure. THAT is critical to LP operation on a refer. Low LP pressure will still yield a blue flame. Also, Did you pull the baffle and did you clean out the flue tube the baffle is in? ANY rust or blockage around that spiral baffle will hinder flue temp operation. You need to state how old the RV/Refer is. Is it possible the baffle has rusted/corroded and is not as long as it needs to be? Doug