Problem 1996 wilderness - atwood water heater issues

[justin2882]

Hi everyone, I have a bit of a question. This is my hot water heater. Its a 6 gallon propane one, with a electric ignition system. Atwood GC6AA-8E specifically. Its been failing more and more over time. The last couple of weeks, it has been essentially useless.

2 years ago when I bought the trailer, it would sometimes keep the water hot at a conistent tempature. Most of the time, I would flick the interior switch off then on again. the switch would light up till ignition, then it would then spend ~30min heating the water all the way up before shutting off. Over time, it has become worse. As of 3 weeks ago, the light had not turned on in a very long time. It never kept itself hot and always required being turned off then on. Sometimes it would be tempermental and refuse to turn on, and usually wouldn't heat the water all the way like it used to.

1-2 weeks ago, it suddenly started shutting off after 5-7 minutes and refusing to even try and ignite again until 30 minutes to 2 hours later. I endured a week or two of cold showers before getting fed up and started to mess with it.

I began messing with it. I figured it was the primary thermostat first, so did a temporary bypass with a mechanical winding timer, as the safest jerry rigged option I could think of, without turning the water heater into a bomb lol. I didn't really trust the saftey's on it. That didn't work. Bypassed the saftey 160F thermostat. That seemed like it worked at first? But then shut off early and refused to turn on again. I took the timer out of the loop entirely and tested it without thermostat or timer. This worked? That was a couple hours ago. It stayed on for 15 minutes, with me sitting there watching it. Turned off once at 7 minutes, then turned itself right back on. I had thought it was the brains, ie the black control box in the upper right. If it turns on with me watching it for 20 minutes again tommorow morning I will assume its the thermostats? Otherwise, im tempted to say I need a new control board. I'm not sure though. It could also be the burner tube? All the wires are clean, I checked everything for corrosion and rust. Cleaned the corrosion off the thermostats (and replaced the female plugs which were corroded), everything else was fine.

I included pics of the original setup, my jerry-rigged timer solution, and the control board.

Does anyone have any ideas or diagnosis for this thing?

 

[allenlook]

You've removed the safety plastic plug and replaced it with a metal one, so yeah, if the OPV fails you have put yourself one step closer to a mishap. That steel plug will also galvanize itself stuck in that aluminum tank, so I'd put a plastic plug back in if it were me. Atwoods don't have anode rods, just plastic plugs.

One of the discs is a thermostat set to about 160 degrees, and it will turn the unit on and off to maintain the temperature. It also has a meltable fuse in a clear plastic sleeve that sometimes fails inside and works intermittently if you wiggle it. Bypassing that temporarily is a first troubleshooting step, and replacing it with a new one if it has failed.

The other disc is an overheat trip device, and it will lock out the control board at 180 degrees to prevent scalding. You have to reset the board with on-off to get it working again.

If someone replaced the thermostat disc with the wrong one (higher temp), it's possible the overheat trip was triggering first and shutting down the board, requiring a constant reset.

I would replace them both with new proper discs, rewire the fusible link, and re-test. If still bad, I would replace the board, they're cheap on Amazon.

 

[justin2882]

You've removed the safety plastic plug and replaced it with a metal one, so yeah, if the OPV fails you have put yourself one step closer to a mishap. That steel plug will also galvanize itself stuck in that aluminum tank, so I'd put a plastic plug back in if it were me. Atwoods don't have anode rods, just plastic plugs.

One of the discs is a thermostat set to about 160 degrees, and it will turn the unit on and off to maintain the temperature. It also has a meltable fuse in a clear plastic sleeve that sometimes fails inside and works intermittently if you wiggle it. Bypassing that temporarily is a first troubleshooting step, and replacing it with a new one if it has failed.

The other disc is an overheat trip device, and it will lock out the control board at 180 degrees to prevent scalding. You have to reset the board with on-off to get it working again.

If someone replaced the thermostat disc with the wrong one (higher temp), it's possible the overheat trip was triggering first and shutting down the board, requiring a constant reset.

I would replace them both with new proper discs, rewire the fusible link, and re-test. If still bad, I would replace the board, they're cheap on Amazon.

Saftey plastic plug? Im a bit confused. There are two thermostats, the one on the left is the 160F overheating saftey and the one on the right is the normal 140F thermostat. I dont know of any plastic plug I have messed with in the past. Maybe something from the previous owner?

The temps printed on the sides of the thermostats read 140F and 160F respectively. They appear to be original. I believe we have the same understanding of how it works though!

Will do with that plan, thanks.

 

[allenlook]

OK, those temps are close, and my memory is as bad as my wife tells me it is the E.C.O. can be as high as 180 on some, though.

The disc locations aren't super important, although if you order new ones you may get a foam cover that tells you the E.C.O. should be on the left, and the normal T-stat should be on the right. The red wires go to the E.C.O. and the brown ones go to the T-stat. There's nothing important about their left-right orientation as long as the wires reach.

https://www.amazon.com/91447-Heater-Thermal-Cutoff-Atwood/dp/B0CN14GMZR?tag=rvf01-20

The drain plug in the Atwood should be plastic, not the shiny steel one that is currently installed. I've actually had them blow out when the threads got tired and the unit had a bad TPR valve, got a stomach load of hot water before I learned to stand to the side. The deformable plastic is another layer of "safety" for the device, and for all of your fittings and appliances inside.

https://www.amazon.com/Genuine-Dometic-Water-Heater-91857-2/dp/B0007XVWW0/?tag=rvf01-20