attitude or altitude?

[MyronL]

Well today there seems to be only two conclusions to be drawn. As a 3-way, the Dometic RM8551 fridge is a lemon, or, the fridge is adversely affected by altitude. Or both.

Yesterday I disassembled the burner lines and gave everything yet another thorough cleaning. The 1/8th tubing, the orifice, even the electrodes creating a spark, everything connected to producing a healthy, robust pilot light, all once again cleaned and blown out as best as humanly possible.

Then I turned the fridge on to propane, 5 full dots. When I did that, at 3:40 PM it was 87°F in the trailer and 68° in the fridge. At 6:10 PM last night I have a very, very robust pilot light and the chimney is quite hot. (So yes, the regulator pressure is just fine.) But, it was 90° in the trailer, 73° inside the fridge.

This morning at 7:24 AM, after all night on 5 dots propane, it is 64°F in the trailer, and --- 55°F in the fridge! Terrible.

How can I have such a robust pilot light but no commensurate propane cooling? See that towel over there? Just threw it in. To paraphrase an old Frank song… My story is much too sad to be told, but everything seems impossibly un- cold.

This is all insanity. When looking for a replacement fridge for your rv before paying the big bucks you need to know the following criteria.

• Will it fit inside the door of the trailer?
• Is it the right size for your cabinet area?
• Will it work in hot weather?
• Will it work at the altitude you will be camping at?

Does Dometic tell you that? Not that I can find. I heard they make a fridge specifically for tropical zones (Australia?) but apparently they are keeping that a secret here in the US. Zero reference if they also make a fridge for higher elevations. The Dometic website is such a jumble, so slick, but absurdly inept for the real world.

Note I did include the word “attitude” starting this topic.

[cpaharley2008]

Too bad the refer does not make a sound like the water heater does when it is warming water, you can hear it's operation.

[Greg A]

You’ve been wanting to do a trip, Myron. Have you called these folks to see if they can do an Amish rebuild for you? https://jc-refrigeration.com/
I think they let you stay at the facility till the work is done. You could have a trip, an adventure, and be the test case for this.

[alanmalk]

Originally Posted by MyronL

...
At 6:10 PM last night I have a very, very robust pilot light and the chimney is quite hot.
...

Myron: Is there any way to confirm that the main burner has ignited? Perhaps by inspecting at night with someone inside to turn the 'fridge on and off?

I haven't done this myself so can't advise, but I am reasonably certain I can hear the main flame come on and off when in a quite location.

My 'fridge is mostly working, at least sometimes. But there was one trip where it failed to ignite. Solved that problem with a couple of hammer taps to the burner - not knowing what else to do at the time and being far from civilization.

--
Alan

[MyronL]

You lost me there, Alan. in my pilot picture, is not that the main flame, and only flame in the fridge?

Say, wouldn't it be swell if some suit working at Dometic sees this thread and addresses these issues?

[rubicon327]

Myron: Doing a little research I found someone who indicated on a Keystone Forum they had problems at altitude until they changed out the control board with one from Dinosaur Electronics. Taking a shot in the dark here but it might be worth a try. You would need to determine if they make a replacement for the RM8551. It is not obvious from their site.
https://www.dinosaurelectronics.com/Dom_boards.htm

[escape artist]

Originally Posted by MyronL

You lost me there, Alan. in my pilot picture, is not that the main flame, and only flame in the fridge?

Say, wouldn't it be swell if some suit working at Dometic sees this thread and addresses these issues?

Hi: MyronL... Did you plug and insulate the hole in the bottom of the door panel. Dometic put them in so you could reverse the door swing. I stood beside ours one summer with shorts on and nearly froze my shin!!! Alf Escape artist N.S. of Lake Erie

[UncleTim]

Originally Posted by MyronL

There’s a thousand feet difference in altitude between my yard and Tom’s in Albuquerque. That just can’t be significant enough to effect performance on propane. But, maybe it is.

Have you considered taking it back down the thousand feet and trying to ignite the burner again? What if it works again down there? Run it hard for a day and come back home with it on!

[MyronL]

Appreciate the suggestions. Did this test at lower elevation. Looks to me clear evidence is that altitude is the factor governing cooling performance.

Repeat: fridge cools great when on shore power or on battery power when towing.

Time/Temp in fridge/Temp in trailer ....Comment/observation

10:40 am 64/ 71 .......Home at 6700 ft elevation - Turn fridge on to battery power 5 dots and tow down to Albuquerque.
11:13 am 63/ 73 .......Arrive at ABQ - it is now at 5,474 ft elevation (Home Depot on Eubank Blvd.)
11:26 am 62 ............At Home Depot parking lot - Switch fridge to propane, 5 dots
12 noon 58/ 79 ........Waiting, watching. See fridge temp dropping at the lower elevation

1 PM ....57/ 83 .............Drive to Cabellas in ABQ, elevation now 5,148 -still on propane 5 dots

2:40 pm 64/ 89 ....Left ABQ – still on propane, drive home. Now home and fridge temp has now jumped back up to 64. Pilot light still good.

[gbaglo]

I takes a day, at least, to get the temp down to 40F on electric. You keep changing location and mode. The fridge doesn't have a chance.

[MyronL]

My test though, was merely to find out if the fridge temp would begin to drop because of the lower elevation . And it did, by 5 degrees. Driving around? Not relevant. Waiting for 40 degrees? Unnecessary. It was not until when I drove back home on propane, to 6700 ft, instead of holding fast, that the temp spiked back up.

[Greg A]

No way to really determine if the propane side of things is functioning, higher altitude or lower altitude, until it brings it into acceptable range below 40 degrees, which is what I think Glen is saying. I've seen these refrigerators cool to low 50's/high 40's and not go any lower when they aren't working properly regardless of altitude.
Driving can also cause the temp to rise some on propane, especially if the fridge is having problems running on propane to begin with.

[MyronL]

I trust Tom's RV. There is no better independent RV service shop in the city.

Back in March when I first took the trailer into Tom's for the propane problem he kept the trailer on his ABQ lot for 10 days. They replaced the regulator, poked and probed, adjusted everything. A thorough fridge exam and assured me the propane side was perfect, showing 29 degrees. I towed it home and it sat there for a week. Then I went out and turned fridge on to propane, as a test, and it again refused to cool the fridge. Took it back to Tom, He retested, kept it another week, said could find nothing wrong, that it was working just fine on propane.

The fault, my dear Watson, is elementary.

[cpaharley2008]

Just leave the trailer and use it while at Toms...............

[Vermilye]

One check you might try is to measure the temperature of the boiler cover with an IR thermometer, and compare at different altitudes, and with 120V operation.

We had a case a few years back at Quartzsite where a refrigerator wouldn't cool on propane, and while the cover felt hot, it was actually measurably cooler when on propane than when on 120V. I don't remember the cure, but when fixed, the cover temperature was quite a bit higher than when it wasn't working. Again, in both cases, it felt hot.

[MyronL]

What is an IR thermometer? Was that fix done at Quartzsite?

[Vermilye]

IR Thermometer and the fix was done at the Q. I believe that cleaning the orifice solved the problem, but it may have been adjusting the regulator pressure. In any case, you couldn't feel the temperature difference, but the IR thermometer showed it.

[rubicon327]

Originally Posted by MyronL

Back in March when I first took the trailer into Tom's for the propane problem he kept the trailer on his ABQ lot for 10 days. They replaced the regulator, poked and probed, adjusted everything. A thorough fridge exam and assured me the propane side was perfect, showing 29 degrees.

Myron: I assume nothing. When they replaced the regulator did they hook up a manometer and adjust the regulator to maintain 11" w.c. minimum when 50% appliance BTU load is on the regulator? This would result in approximately 12" w.c. measurement with no load. I have seen bright blue flames misleading owners because they are too small and not providing the required BTU's. Was 29F the fridge or the freezer? If it was the freezer this can also be misleading because the ammonia passes through the freezer evaporator first and then on to the fridge. I have seen situations of cool freezers and warm refrigerators.

[MyronL]

Agreed. It is never good to assume anything. I always first ask my surgeon if he washed his hands.

[rubicon327]

Originally Posted by Vermilye

IR Thermometer and the fix was done at the Q. I believe that cleaning the orifice solved the problem, but it may have been adjusting the regulator pressure. In any case, you couldn't feel the temperature difference, but the IR thermometer showed it.

If you use one of these make sure you are the same distance away for all tests. These are quite sensitive to the field of view. With a distance-to-spot (D/S) ratio of 10:1 if you are trying to measure a 2" spot you should be no further than 20" away.
See Accuracy at this link learn more: https://www.grainger.com/content/qt-...d-thermometers

As a secondary use some guys use these to shoot their wheel hubs on long hauls to check for overheating.