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.

[joshuajim]

I've thought about this for a few days and while the regulator "may" compensate for altitude, I realized that most gas appliances - i.e. residential furnace, residental water heater, gas dryer etc. ALL have high altitude kits that change the jets for higher altitude.

This tells me that RV appliances would also benefit from this change (which generally is not available).

[wnjj]

joshuajim wrote:
Just a thought, but does the regulator self adjust pressure as altitude changes, i.e. remain steady at 11" regardless of altitude? It would seem that as barometric pressure on the diaphram reduces at altitude that the w.c. would increase.

I suspect the regulator is always holding 11" WC relative to atmospheric pressure. The absolute pressure of the LP would necessarily decrease but that makes sense if you want to keep a balanced mixture of air/fuel at the appliances.

The movement of the diaphragm is what causes the regulator to alter the internal gas pressure.

[joshuajim]

Just a thought, but does the regulator self adjust pressure as altitude changes, i.e. remain steady at 11" regardless of altitude? It would seem that as barometric pressure on the diaphram reduces at altitude that the w.c. would increase.

[d-mac1]

Just a late follow-up after trying the trailer in exactly the same location where it had problems last year:

The new circuit board and new ignitor fixed the problem. It worked perfectly at 10k' in spite of Dometic's comments about it not guaranteeed to work at anywhere near that altitude. Dometic was right about 1 thing...it wasn't a jet related problem.

Maybe this winter I'll put the old ignitor back in and see if the cold causes it to be faulty. If it works fine, I'll strongly suspect the old circuit board.

Thanks again for everyone's help.
dmac

[grizzzman]

Good to hear you have copper. If I can prove out the pressure change, I will be going copper. The hoses are propane certified. Remember you have hose at the regulator. (I estimate about 30' of rubber line in mine) I believe that ease of install along with speed are the reason. I will be headed to the Sawtooth mountains this weekend in Idaho. Perhaps my new water column gauge will shed some light on this issue.

[d-mac1]

Yep! Thanks. Mines a copper line to the burner assembly.

I wonder if you can replace your rubber line with copper. You wouldn't think rubber is even safe as a propane line!!

Surely the RV industry, and its suppliers, are building us quality products? (don't die laughing!)

[grizzzman]

d-mac1 wrote:
Supply lines?? Supplying what? Sorry not sure about your question.

OK I will explain. My 2007 class C had a Dometic fridge. This fridge worked just fine at 10000 feet no problem. However my 2016 Domestic was going out at 8600 feet. One of the differences is the 07 had copper lines and the 16 has "all" rubber lines. Why does this matter? Well here are the fact's 1. At higher altitude the mix goes a bit rich. 2. The colder propane gets the more dense it becomes. 3. A rubber line will contract when it gets cold. The copper line not so much. During the day the unit would spit and sputter and it would continue to spark. After a few minute's it would settle down and go quiet. At night it would go out. It would relight after a few trys. I took it apart and watched the flame. The flame was lifted off the burner. This is why it would continue to spark. It did not have a path to ground so the control board believes it was not lit. It is my theory that when the hose contract's the pressure raises enough to over pressure the flame and given a bit of time the pressure drops and the flame goes normal.
That answer your question?

[d-mac1]

Supply lines?? Supplying what? Sorry not sure about your question.

[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.

Does your unit have all rubber supply lines?

[d-mac1]

Well...not sure about my previous question, but I just installed my new board and electrode/igniter. Gonna go start it up and see what happens. It should work fine cuz its warm. I won't have any idea if the problem is resolved until I take it to altitude again.

[d-mac1]

I have purchased a new board and a new electrode. I may install both unless I find the electrode aspect super easy to do in the field. Ideally I could just try one at a time to see exactly where the problem is.

The shop that prdered me a board had said they order through Dinosaur, but I am skeptical because I didnt see Dinosaur on the board. Should it so state?

[d-mac1]

Update -

I called Dinosaur Electronics. They can't sell me a board, but I could buy one through one of their distributors. Thank you for the info about them. Heres the good news...they have a tech support group that, even though they can't sell me a board, will help out retail customers such as me!

So I talked to one of their guys and he thinks we are on the right track BUT, he said its possible that its simply the ignitor. He said its possible that there is a bad spot in it somewhere which the 2000 volts sent through it to light the flame jumps right through, but the little bit of electrons its sensing from the flame don't make it back through.

Why does it only happen at altitude I asked? He said perhaps its because of temperature...not altitude! I was like...AHA!! That makes some sense!!

So, I'm in the process of getting a $20 ignitor and if that doesn't fix it, then it must be the board. He said the same thing could be going on with it in its welds from the factory...ie defects that cold temperature exacerbates.

Will update again once I have a chance to test out the new ignitor.

Thanks again for everyone's responses. It all adds up to getting me going in the right direction.

Dmac

[jmckelvy]

Sounds like the flame sensor is possibly the issue. There is info on youtube re testing the flame sensor. Here is one:

https://www.youtube.com/watch?v=8XucClM6bJQ

[Chris_Bryant]

You don't have a thermocouple- actually, the thermocouple style would probably work better, but...
I would remove the electrode and lightly sand the end, wipe the ceramic down with silicone lube on a rag and reinstall- then if needed play with the gap adjustment.

I haven't had any dealings with a Dinosaur replacement for this type, though in their straight ignition modules, Dinosaur is usually better at flame sensing than the stock, but I haven't had any issues with the stock board, either.