Atwood water heater sensors?

reeman · 03-15-2021, 10:10 AM

Our model is the electric/gas automatic GC 6AA10E. Electric is working and I changed the thermostats so I know they are not the issue with the unit.

The heater starts correctly on gas then does not hold in so it is sparking correctly but does not seem to be sensing the flame which is working fine.

I suspect that there must be a failure prone photo sensor or some new fangled weird heat sensor somewhere behind the circuit board which I have not taken off or fiddled with quite yet.

I adjusted the venturi so that it does not woof and has a nice blue flame so I know that this is not the issue. The flame was set too rich and might have sooted up a sensor somewhere. I think that a tech or the previous owner must have screwed up and set the venturi too weak in the past because the unit had been fiddled with when we bought the trailer last year. Someone had tried to wind proof the water heater with sillycone around the cover which caused it to choke out so there might be some sooting in the firebox.

The control inside the trailer does not show a fault light so it is not a reset our failure issue with the brain on the circuit board. It worked for about 20 minutes to get the water warm when I first started it, but now just cuts out after running about 20 seconds. So there is most likely a sensor issue happening because the gas is not the problem and the flame is constant without drop outs.

Anyone here had the same issue because it seems there is no standard thermocouple to sense the heat from the burner, or if there is it must be somewhere else, there is none on the spark setup the to the gas control like on standard old school water heaters.

The old tanks were easy peasey just change a thermocouple and bobs your uncle, now it seems everything has to have some new fangled expensive failure prone brain to simply know if there is a fire happening!

**creativepart** · 03-15-2021, 10:26 AM

I was told by a tech at Atwood that it is a thermocouple and it is inside the spark electrode. They describe it as a Spark and Sense electrode. I don't have direct experience with this... but that's what the tech told me.

https://pdxrvwholesale.com/products/...embly-93868%20

neub · 03-15-2021, 10:35 AM

Quote:

Originally Posted by creativepart

I was told by a tech at Atwood that it is a thermocouple and it is inside the spark electrode. They describe it as a Spark and Sense electrode. I don't have direct experience with this... but that's what the tech told me.

https://pdxrvwholesale.com/products/...embly-93868%20

X2, caused exact same problem on our atwood. Replace the spark igniter/thermocouple and problem solved

Morich · 03-15-2021, 11:04 AM

I would want to look carefully at the last note on the link above as a real good prospect.
They can be fussy and something as simple as a bug in the wrong spot can make a good one look bad.
If folks have been adjusting things, it is always good to check if they knew what they were doing?

reeman · 03-15-2021, 12:15 PM

Quote:

Originally Posted by Morich

I would want to look carefully at the last note on the link above as a real good prospect.
They can be fussy and something as simple as a bug in the wrong spot can make a good one look bad.
If folks have been adjusting things, it is always good to check if they knew what they were doing?

My sentiments exactly. It just worked correctly and heated up to the correct temp before switching off for the first time. My guess is the electrode that creates the spark was the problem with the gas set too rich by someone who did not understand what a venturi is or how it mixes gas and air for a clean combustion. Lesson here is to always check the simple stuff like the air fuel mixture, combustion air access first.

When the unit worked on electric it was heating up too much and causing the pressure relief to go off sending the water up to the boiling point. Changing the eco thermostat fixed that issue. I would imagine that using this particular type of fixed thermostatic unit at higher elevations might be a bit of a trip with water boiling at lower temps.

We will be taking the trailer up to higher elevations so my guess is that it is best to operate it only manually, and especially shut it off at night AND only use it by shutting it off before it cycles or pops the pressure valve. The inconvenience of having to turn it on in the morning is not going to be a concern and seems like a sensible safety precaution with these heaters IMO.

The thermal sensing spark electrode may very well have cleaned up by itself so no need to change that out as it starts and now runs correctly with the right air fuel mixture and enough air getting to the burner. Thanks for the info that it is a thermo electric setup not an electric eye setup like the large commercial units that I once worked with.

BTW the correct venturi setting is appx 1/4 of the possible setting. It was set almost closed as far as the screw would allow.
Amazing the things you can learn simply by reading the manual that came with the unit. RTFM first seems the best solution as always.

**creativepart** · 03-15-2021, 03:03 PM

Reeman, there is an adjustable thermostat that lets you set the water temp.

It replaces the 'stat that's just screwed in to touch the side of the tank replacing the normal 'stat.

https://rvpartsexpress.com/product/a...rmostat-93105/

It might help you sleep better knowing that you're better in control of the WH's temperature.

reeman · 03-15-2021, 05:21 PM

Quote:

Originally Posted by creativepart

Reeman, there is an adjustable thermostat that lets you set the water temp.

It replaces the 'stat that's just screwed in to touch the side of the tank replacing the normal 'stat.

https://rvpartsexpress.com/product/a...rmostat-93105/

It might help you sleep better knowing that you're better in control of the WH's temperature.

Thanks.. It is a little concerning having a hot water tank under your pillow working at the point which the safety device goes off at night. If I was really crazy I would just put a brass drain valve and a plug in where the pressure relief valve is plugged in.

It also has the added feature of not performing very well in windy conditions, I guess that is most likely the reason why someone tried to seal up the cover with sillycone! If it is windy at all in my yard where it is parked, then it really effects the unit's ability to keep the flame steady.

The older dometic heaters were not as finicky and much easier to service, our 13 foot Scamp was a little gem and I sorely miss it. Wish that we could afford both because the little Scamp was great for one person on a fishing trip to say the least, even though it was low to the ground it was no problem at all because of the short wheel base with a very short overhang.

l1v3fr33ord1 · 03-15-2021, 07:18 PM

reeman-

There's a fellow with the handle "Old-Biscuit" over on iRV2. He helps solve water heater problems for many folks there. Here's a link to a typical post of his. You may want to post any water heater problems over there, to catch his attention, in addition to here.

reeman · 03-15-2021, 11:05 PM

Like the guy in the youtube vid the first time we winterised a trailer I removed the drain plug on our Scamp foolishly but only once: without fully releasing the pressure adequately or cooling it down enough so that it didn't pressure up with the tap shut off! The plastic plug knee capped me and almost hit my wife in the kisser' The pop and my wife's shriek and my sudden expletives scarred the crap out of our neighbour's young dog who was watching us rv newbees bumbling away in the driveway that day.

Looking on the bright side though: the tank drained in one hell of a hurry.

Lessons some times are best learned the hard way. Don't unscrew the plug unless you are certain that the tank is not under any pressure at all.

https://www.youtube.com/watch?v=H1DhlktQ8Rk