Water heater ignition failure

[Aroadracer]

On my last trip, I kept getting a water heater ignition failure on my propane fired Atwood water heater in a '99 Country Coach Affinity. At first it would fire for 20 minutes or so, long enough to heat the water, and then a vocal alarm would announce ignition failure and the co2 alarm would go off. I found a ground wire loose on the controller so tightened it. Through the weekend it would trigger the alarm earlier and earlier (after a few minutes). I would only turn on the water heater to take a shower and usually the water got warm enough to do so. By the end of the trip, it wouldn't run long enough to heat.
I tried searching here for similar issues but maybe I'm not searching right?
Does anyone have any advice to trouble shoot?
One other clue is I smell a slight peculiar smell when the co2 alarm goes off. I'm not sure but this may be the original water heater as my coach only has 83,000 miles. Maybe it is time to replace it.

[Aroadracer]

Correction: it was my LP gas detector going off so I probably have a gas leak somewhere

[Aroadracer]

I think I found the problem. I couldn't find a gas leak but when I pressed on the main wire harness connector to the control module I could hear the solenoid clicking. I could hold the connector a certain way and the burner would fire. When I let go, the burner would go out. I cleaned the contacts and reinstalled and the burner fires and stays lit.
Do most people keep their water heater on all the time or only when they need hot water?

[Rsponsford]

Originally Posted by Aroadracer

Correction: it was my LP gas detector going off so I probably have a gas leak somewhere

When the LP leak detector goes off does it automatically shut off the LPG to the coach? If so, perhaps there's nothing wrong with your water heater but you have a gas leak somewhere else. I have a Country Coach Concept and hard pipe was used for all the LPG lines so a LPG leak is more likely to occur at one of your appliances than the gas lines themselves. The most common cause I've witnessed for a leak is if the stovetop does not get turned off all the way. The gas valve and burner for your water heater are located and vented to the outside of the coach so I doubt a leak there could be picked up by the LPG detector.

[Aroadracer]

Originally Posted by Rsponsford

When the LP leak detector goes off does it automatically shut off the LPG to the coach? If so, perhaps there's nothing wrong with your water heater but you have a gas leak somewhere else. I have a Country Coach Concept and hard pipe was used for all the LPG lines so a LPG leak is more likely to occur at one of your appliances than the gas lines themselves. The most common cause I've witnessed for a leak is if the stovetop does not get turned off all the way. The gas valve and burner for your water heater are located and vented to the outside of the coach so I doubt a leak there could be picked up by the LPG detector.

Yes, it shuts off the LPG to the coach and I get a check light on my fridge. I turned the water heater control off and reset the LPG detector and reset the fridge and all is ok. I leak checked the connections at the water heater and all seems good. I'm thinking when the burner went out due to a poor connection at the control module, it kept trying to re-fire until there was enough gas build up to set off the LPG alarm. I just ran it for about 20 minutes and the burner was still going and no LPG alarm so I'm hoping all is well. This old coach is pretty fascinating to me and complex and I'm learning a lot as things act up.
One other thing I learned is there seems to be a second heat exchanger in the water heater that comes from my hydronic heat system. I can see two high temp silicone heater hoses in addition to the two hard plastic line connections. I thought I read something about this in the manual. I guess this could be used as backup water heat if the propane goes empty or the burner/igniter fails.
Thanks for your input!

[Rsponsford]

...

[Aroadracer]

[emoji106]

[Rsponsford]

Originally Posted by Aroadracer

Yes, it shuts off the LPG to the coach and I get a check light on my fridge. I turned the water heater control off and reset the LPG detector and reset the fridge and all is ok. I leak checked the connections at the water heater and all seems good. I'm thinking when the burner went out due to a poor connection at the control module, it kept trying to re-fire until there was enough gas build up to set off the LPG alarm. I just ran it for about 20 minutes and the burner was still going and no LPG alarm so I'm hoping all is well. This old coach is pretty fascinating to me and complex and I'm learning a lot as things act up.
One other thing I learned is there seems to be a second heat exchanger in the water heater that comes from my hydronic heat system. I can see two high temp silicone heater hoses in addition to the two hard plastic line connections. I thought I read something about this in the manual. I guess this could be used as backup water heat if the propane goes empty or the burner/igniter fails.
Thanks for your input!

You may also want to check and see if your water heater has a thermocouple that needs to be replaced. The job of the thermocouple is to sense if there's a flame when the burner should be operating. If it does not sense a flame it will shut off the gas to the water heater to prevent unburned gas from flowing. Thermocouples break down over time as they are exposed to heat whenever the burner is operating. If this is the source of your problem then it will begin as an intermittent problem but eventually stop working altogether.

If you haven't already, be sure to cycle the stovetop as well and then make sure it is completely turned off. More than once my wife has left a burner partially on.

Yes, your hydronic heating system also circulates through a heat exchanger in the water heater as an additional method of heating the water.