Refrigerator & High Altitude

[d-mac1]

I've got a Dometic 2852RBX that works ok most of the time, but when I had it at 9,750' last year it kept going out and wouldn't relight. It would try, but I'd come back after being gone for awhile, or awaken in the morning, and the check light would be on.

My dealer said its the orifice size that needs to be changed for high altitude and said to talk to Dometic technical support. I called and was not happy with the level of 'support' I was provided. Among some curt responses, I was told they aren't guaranteed to run at over 5,000'...NO further help! I live near Denver....EVERYTHING is above 5,000'!!

I continued to try to get some information on what size orifice would make it work at altitude to no avail. Finally the unhelpful phone rep went to ask 'the boss' if it can even be changed on my fridge and when she came back on the phone she told me NO...I can't change the orifice in my unit. I just looked and yes it can be changed. It has a 53 in it now.

Since the problem occurs at high altitude, less air pressure, I'm guessing (if this works like a carburetor) means I need less propane, thus a smaller orifice (or jet if you will).

Does anyone know if I'm on the right track so that I can keep my fridge running next trip up there? If I could get the right sized orifice, my thoughts are to take it along on a trip and if problems, put it in until returning to lower altitude.

In case you are wondering, I was at my dealer because I was guessing the problem was a faulty regulator, but they said thats not the problem if it works fine otherwise.

Thanks.

[Gjac]

After 3 pages without a concreate answer I will just give you my experience. A while back my burner was giving me problems because the slots were rusting out and the flame was flickering. I made a slide mechanism to adjust the air to fuel ratio like on a water heater, because I could not get a direct replacement burner for it due to its age. I noticed when I camped at higher altitudes I would have to slide the mechanism over to allow more air and maintain a blue non flickering flame. When researching burners I noticed some burners had more slots than others. So I would look at modifying or buying a tube with either more slots or slightly larger input holes for the air to enter the tube. I would not change the orifice. You can put a screw driver tip over the slot to see how the flame changes in color to see what I am describing.

[d-mac1]

Chris Bryant wrote:
Some Dometic models have no thermocouple, but if yours does, testing is easy- just measure the voltage it puts out in the flame. For the non-integrated igniter boards, the thermocouple needs to put out above 15 mv, with ~25-30 mv being the norm.

For the integrated igniter boards, where the spark wire goes right to the main board, there is no thermocouple. Flame sensing is done purely through the electrode and flame itself.

Sounds like a tax deductible vacation to the high country is called for 🙂 (I grew up in Colorado).

Come on out! Its ALOT more crowded now than it used to be though. At least the front range is.

I am thinking my fridge doesn't have a thermocouple. See the pic.



I just went out and turned the fridge on. One click and insta-light. I wish I didn't hafta haul the trailer a few hours to get to altitude to see what its gonna do. Like I said....last time when we were on our way home and I stopped for a while to visit some friends (so I turned off the fridge cuz not level), when I went to leave, it lit right away, but kept clicking the ignitor and eventually quit.

Maybe it has nothing to do with altitude and is simply an intermittent problem. Anyone know how to test my board or ignitor?

Thanks.

[d-mac1]

wgriswold wrote:
Some people have reported that leaving the cover off during operation increases the availability of air and helps at altitude.

What color is the flame at altitude?

I don't know. At 6500' its blue. Assuming same at altitude but I didn't disassemble to look.

[Chris_Bryant]

Some Dometic models have no thermocouple, but if yours does, testing is easy- just measure the voltage it puts out in the flame. For the non-integrated igniter boards, the thermocouple needs to put out above 15 mv, with ~25-30 mv being the norm.

For the integrated igniter boards, where the spark wire goes right to the main board, there is no thermocouple. Flame sensing is done purely through the electrode and flame itself.

I've thought a lot about hi altitude operation- never been able to get what I feel is a good answer. The trouble is, if you say there is less air so I need a smaller orifice- all that does is get you a smaller flame, still starved for air. Because there is no air adjustment on these, and all models actually use the same burner with different orifices, I just don't know how to solve that problem. It could be that a *higher* lp pressure would pull more air in to the mixture, but I would want to do quite a bit of experimentation.

Sounds like a tax deductible vacation to the high country is called for 🙂 (I grew up in Colorado).

[d-mac1]

Ok....sounds logical...but I wonder why it happens only at high altitude? At 6500 where I live its fine. When I first bought the trailer it did about the same thing all the time. They put a new board in it.

I wonder if there is a way to test the thermocouple?

[Joe_Way]

stevenal wrote:
I recommend the Dinosaur Electronics replacement boards if you get to that step.

X2

[stevenal]

d-mac1 wrote:
Cleaning it didn't fix it. I was at around 9k last weekend and same problem. Here is what it does when trying to run on propane and the problem arises when it tries to light.

It'll light, but it will keep sparking the ignitor (even though I can hear it burning). It'll continue to spark the ignitor and after a short while, it'll stop sparking it and I think it then closes the gas valve, so the pilot goes out. Repeat, repeat, quit.

I've got the wind covers off again and thinking the probe that sticks into the flame must need to be lowered or something. Its the only thing I can see that senses temperature (ie.. that would tell the unit that the flame is lit...but if this is the problem, why the flame isn't as hot at higher altitude is a bit of a mystery to me.

It's important to know that the thermocouple isn't the only thing that senses whether the flame is present, the igniter itself performs this function as well. The continued sparking makes me suspect this part of the circuit. I believe it works by measuring the conductivity of the flame, and the altitude might affect this somewhat. You may need to adjust the igniter, replace the igniter, or replace the board. I recommend the Dinosaur Electronics replacement boards if you get to that step.

[MEXICOWANDERER]

A 198 Norcool of mine worked satisfactory at Saddlebag Lake CA. elevation 11,220 ft. I wonder what gives?

Not Frigid Nor Cold

[wgriswold]

Some people have reported that leaving the cover off during operation increases the availability of air and helps at altitude.

What color is the flame at altitude?

[d-mac1]

Cleaning it didn't fix it. I was at around 9k last weekend and same problem. Here is what it does when trying to run on propane and the problem arises when it tries to light.

It'll light, but it will keep sparking the ignitor (even though I can hear it burning). It'll continue to spark the ignitor and after a short while, it'll stop sparking it and I think it then closes the gas valve, so the pilot goes out. Repeat, repeat, quit.

I've got the wind covers off again and thinking the probe that sticks into the flame must need to be lowered or something. Its the only thing I can see that senses temperature (ie.. that would tell the unit that the flame is lit...but if this is the problem, why the flame isn't as hot at higher altitude is a bit of a mystery to me.

The 'probe' I'm talking about is item 33 on page 9 in the link. Anyone know how close to the tube it is supposed to be? Its in the flame...gets red hot after a while.

http://www2.dometic.com/e7a015ae-2585-417d-8f59-4e1c6c8be661.fodoc

[dougrainer]

d-mac1 wrote:

wa8yxm wrote:
I think your dealer is speaking through his hat, but there is an air/fuel adjustment that may need to be opened up a bit at high altitude. you need to learn how to adjust it.

Also a full PM run on the Fridge.

Can you please clarify? How do I adjust it and what is a "PM run on the Fridge"?

Preventative Maintenance---PM. AS to the adjustment. There is NONE on the refer. You could adjust the LP regulator, but I would find out what pressure it would need for HI Altitude. Doug

[d-mac1]

wa8yxm wrote:
I think your dealer is speaking through his hat, but there is an air/fuel adjustment that may need to be opened up a bit at high altitude. you need to learn how to adjust it.

Also a full PM run on the Fridge.

Can you please clarify? How do I adjust it and what is a "PM run on the Fridge"?

[wa8yxm]

I think your dealer is speaking through his hat, but there is an air/fuel adjustment that may need to be opened up a bit at high altitude. you need to learn how to adjust it.

Also a full PM run on the Fridge.

[grizzzman]

d-mac1 wrote:
I've got a Dometic 2852RBX that works ok most of the time, but when I had it at 9,750' last year it kept going out and wouldn't relight. It would try, but I'd come back after being gone for awhile, or awaken in the morning, and the check light would be on.

My dealer said its the orifice size that needs to be changed for high altitude and said to talk to Dometic technical support. I called and was not happy with the level of 'support' I was provided. Among some curt responses, I was told they aren't guaranteed to run at over 5,000'...NO further help! I live near Denver....EVERYTHING is above 5,000'!!

I continued to try to get some information on what size orifice would make it work at altitude to no avail. Finally the unhelpful phone rep went to ask 'the boss' if it can even be changed on my fridge and when she came back on the phone she told me NO...I can't change the orifice in my unit. I just looked and yes it can be changed. It has a 53 in it now.

Since the problem occurs at high altitude, less air pressure, I'm guessing (if this works like a carburetor) means I need less propane, thus a smaller orifice (or jet if you will).

Does anyone know if I'm on the right track so that I can keep my fridge running next trip up there? If I could get the right sized orifice, my thoughts are to take it along on a trip and if problems, put it in until returning to lower altitude.

In case you are wondering, I was at my dealer because I was guessing the problem was a faulty regulator, but they said thats not the problem if it works fine otherwise.

Thanks.

Dads trailer did the same thing as you described. His fix was to adjust the the electrode (the spark thingie) This unit uses the electrode for spark and to sence if the unit is lit. In his case the unit would spark and it would light then it would go out. He widened the spark gap and this solved the problem. He made the gap a bit larger then the 3/16 gap the Manuel says. So increasing it's resistance a bit allowed the controller to see that it was lit. Easy and cheap to try. 🙂

[d-mac1]

Thanks for all the help guys!

Cleaned everything out and found what looked like a small, thicker hair inside the jet, kinda stuck to the tapered portion. It was only about 1/4" long, but I used a pick to dislodge it and it fell out.

Started to reinstall and noticed that, in order to have the opening of the gas line/jet assembly lined up with the opening that leads to the burner, it would be angled upwards. I was like hmmm. So I looked at the pics I took before disassembly and sure enough, thats how it was. I rectified the alignment and now it is aiming straight at the opening to the burner.

Once I got the air out of the line (I previously installed my new regulator cuz I figured it couldn't hurt) it seems better than before! Its always had a bit of a struggle lighting. Now, it lights on first spark. I've tried it 3x....even after letting it sit for about 1/2 hour. Instant light!

I don't know if I've fixed it or even improved it, but it seems like I've at least accomplished the latter.