Propane Cooktop Fail/Revival

[rbrandenstein]

We had a strange occurrence with our 2017 19 and the 2 burner cooktop. We use it occasionally, but it has always worked fine. We were camping several days in Moab, UT and tried to use it on the last day. There was no hissing sound and it would not light. This was true for both burners. All other propane accessories (Refrigerator, Heater) worked fine.
I called Escape and they didn't have any solid ideas. The regulator seemed to be the only thing that might cause this. They gave me Dometic's number. I decided to wait to call until we reached our destination in Snoqualmie, WA.
Last night, in Idaho, I decided to try the burners and they worked fine.
Has this occurred anyone else? Any ideas what caused this?

[Iowa Dave]

Has not happened to us but I would suspect some sort of an air lock wouldn’t you? Whenever I have any issue with propane I shut off the tanks, take the hoses loose from the tanks move the tank selector flipper back and forth a couple times . Then I put the hoses back on, open the valves very slowly and then fire the furnace or light all three burners. Those check valves on the tanks can be sticky some times. Worth a try because it’s free. Once in a while if you forget to open both tanks and run out on one I’m in kind of a hurry and open the full one too fast and still have no gas till I slow down and take my time. Happens on my gas grill too sometimes after I change a tank.
Iowa Dave

[Brian B-P]

Originally Posted by Iowa Dave

Whenever I have any issue with propane I shut off the tanks, take the hoses loose from the tanks move the tank selector flipper back and forth a couple times . Then I put the hoses back on, open the valves very slowly and then fire the furnace or light all three burners. Those check valves on the tanks can be sticky some times.

Excess flow valves, not check valves, but yes... flow can be severely limited and a reset is needed. On the other hand:

Originally Posted by rbrandenstein

All other propane accessories (Refrigerator, Heater) worked fine.

... so it doesn't seem like there was a propane flow problem - the furnace uses propane at a greater rate than a stove burner and probably won't keep running is adequate flow is not available.

Originally Posted by rbrandenstein

Has this occurred anyone else? Any ideas what caused this?

As Dave mentioned, sometimes you can get air in the line to the stove (f you haven't used it for a long time, or since running out of propane and changing tanks) and need to purge it out before you get a flame. Maybe the stove would have worked earlier if you kept trying.

At low enough temperatures water in the propane (which shouldn't be there, but a small amount of contamination is not uncommon) can freeze at the regulator, obstructing flow. In the right conditions (combination of low temperature and high relative humidity) frost can form on the outside of the regulator, which inhibits heat absorption by the regulator (which is needed to avoid internal freezing) and potentially blocks the regulator vent, interfering with regulator operation. In these conditions, thawing time is often all that is needed for everything to work again. The problem with all of this as a potential cause is that anything happening at the regulator would have affected the furnace and water heater as well.

[rbryan4]

Originally Posted by rbrandenstein

We had a strange occurrence with our 2017 19 and the 2 burner cooktop. We use it occasionally, but it has always worked fine. We were camping several days in Moab, UT and tried to use it on the last day. There was no hissing sound and it would not light. This was true for both burners. All other propane accessories (Refrigerator, Heater) worked fine.
I called Escape and they didn't have any solid ideas. The regulator seemed to be the only thing that might cause this. They gave me Dometic's number. I decided to wait to call until we reached our destination in Snoqualmie, WA.
Last night, in Idaho, I decided to try the burners and they worked fine.
Has this occurred anyone else? Any ideas what caused this?

As it so happens, I had the exact same thing occur a few months ago on the first night camping in the Piney Woods. The fridge and the furnace worked, but the cooktop wouldn't light, and I couldn't hear or smell gas flowing.

I shut everything down and closed the tank valves, unscrewed the pigtails (this step was probably irrelevant but I did it anyway) then reconnected and just opened the valves again. Stove worked. I'm thinking the cause was some sort of vapor lock as Dave suggested.

[Brian B-P]

Originally Posted by rbryan4

I shut everything down and closed the tank valves, unscrewed the pigtails (this step was probably irrelevant but I did it anyway) then reconnected and just opened the valves again. Stove worked. I'm thinking the cause was some sort of vapor lock as Dave suggested.

If that works, it's the excess flow valve. Removing the pigtail resets the valve more quickly, but it will reset (more slowly) without disconnecting.

I don't know what a "vapor lock" would be in a system which only contains vapor. It's not like a gasoline engine, with plumbing that is supposed to be filled with liquid but can form a bubble of vapour if it gets too hot. Air (rather than propane vapour) in propane lines does interrupt operation.

[rbryan4]

Originally Posted by Brian B-P

If that works, it's the excess flow valve. Removing the pigtail resets the valve more quickly, but it will reset (more slowly) without disconnecting.

I don't know what a "vapor lock" would be in a system which only contains vapor. It's not like a gasoline engine, with plumbing that is supposed to be filled with liquid but can form a bubble of vapour if it gets too hot. Air (rather than propane vapour) in propane lines does interrupt operation.

I've no idea if it was a "vapor lock" or an air bubble or whatever, but it wasn't the excess flow safety valves. If it were, the furnace and fridge would not have worked.

[Brian B-P]

Originally Posted by rbryan4

I've no idea if it was a "vapor lock" or an air bubble or whatever, but it wasn't the excess flow safety valves. If it were, the furnace and fridge would not have worked.

Excess flow valves restrict, but don't completely cut off, the flow. The refrigerator might still work happily with it tripped, but I agree the furnace shouldn't.

Unlike a computer, turning propane on and off doesn't really change anything, other than resetting a tripped excess flow valve.