Atwood 6 Gallon Gas water heater

[Aussie66]

Hi all, hoping someone might be able to help,

I have a 6 gallon Atwood gas only water heater, and the PCB died recently, it was definitely the pcb, possibly a broken track or dry-joint, twisting it slightly would bring everything to life.

So I ordered a new PCB, new wiring loom (older pcb & loom) and ignitor probe for good measure. I replaced all the above and am now left with an intermittent fault.

When turning on the heater I have a 50% chance it will ignite. It will either ignite and run or I get a clonk/clonk as the gas valve opens & closes within a millisecond, yet the ignitor continues to click for about 8 seconds before lockout.

When it works the gas valve opens, just one clonk, ignitor starts and off it goes.

I checked the red wire from the PCB which feeds the valve solenoid via the thermostat, when it works I have the 12v continuously, when it doesn’t I get the 12v for way less than a second..

The PCB I got is part number 91367, which is a replacement for the 93257 from 2005 that was installed. I wonder if I have received a faulty board, or I am missing something, like incorrect replacement.

Has anyone any thoughts or similar experience?

[dougrainer]

When it works 10 times out of 12, checking the coils is futile. AS I stated, the Ignitor/Gap/sparking(OR BAD) HAS NOTHING TO DO WITH 12 VOLT POWER TO THE GAS VALVE and keeping the gas valve open. IF you have a failure of Spark system, the gas valve(if operational) will continue to spew LP until the Ignition cycle is done(about 15 seconds). THAT is why the manual states to wait a minute or so between ignition cycles to allow any accumulated LP to disperse. IF you have a lapse of 12 volt power to the gas valve, then the problem IS the PCB board. Doug

[enblethen]

You do not have to remove gas valve to check coils. hardest thing is ground is connected to valve mounting bracket on back side.
There should be two wires coming off valve that goes to ground. Two wires go to the thermal cut out connected to it with a 1/4 inch quick connect. Easiest way is to cut that connector off and test coils.

[Aussie66]

Thanks for the replies everyone, the board came from PantherRV https://pantherrvproducts.com/91367/

While writing this post I also noticed that the packet has part number 91367, dated 10/18/21 but the part I received has 93307 on it, same year. Hmmm

Anyway I have tried over the last hour running the heater, out of about 12 times it worked fine 10 times, only failing twice. Again when it fails the gas valve opens and closes in half a second, red light comes on but still runs the ignition cycle, with obviously no gas running :R.

So going from what’s been written above;

The ignitor, gap is correct and appears to be positioned correctly, sparking between itself and not the tube, and in the path of the flame. Would an ignitor cause the gas valve to open & close immediately? I might put the old one back in.

Gas valves when it has stopped pouring with rain I shall check these, is there a way to remove them? I read somewhere about taking them out to physically check the coils.

I did rewire the gas valve earths but thinking I should look at the wiring as a whole, again when not pouring, and maybe rewire back to the battery.

Batteries are charged via solar, not shore, currently 100% reading 13.5v at the board connector.

I shall make up a 12v lamp to test that theory too.

Thanks for the help so far!

[enblethen]

The ignitor is also the flame sensor. It is a possibility!

[dougrainer]

WHERE did you get the PCB board. 4 or 5 years ago, Atwood/Dometic had thousands of brand new defective PCB boards and replaced those under warranty. At the time I wondered what would happen to ALL those recalled boards. Even Boards that were stocked by suppliers were recalled. I believe some bad actors got hold of those bad boards and now are selling them. There is NO identification to tell which were bad and which were good and the year model of them. But based on your LACK of 12 volts for a few seconds at the gas valve, that points to a defective PCB boards. Ignitor lack of spark or NO spark will not affect the 12 volts to the gas valve. It will stay on until the 15 second ignition cycle ends, and then the PCB will kill power to the Valve. Send it back to your company you purchased from and get a replacement. Doug

[prichardson]

Your symptoms indicate an igniter that is not properly positioned.

[JimK-NY]

Based on my similar experiences with the Atwood, I would start with the ignitor. Make sure the gap is correct and it is correctly positioned in the flame.

[enblethen]

Check the coils on the gas valve. Each coil should read nearly the same.
Check the ground wires don gas valve.
I would never have bought circuit board from Atwood. Dinosaur Electronics circ uit board are far better quality.

[YC_1]

Sounds like you may have the spark misaligned.

Perhaps you can substitute your own 12 volts to the gas solenoid. If the 12 volts that is getting there is not really 12 volts under load the solenoid may not be opening correctly.

Using a digital voltmeter can trick you. The 12 volts going from what looks like full voltage to a lower state and back again can happen too fast for you to see it.

A 12 volt test light at the solenoid might help sort it out by putting a real load on it.

I would also like to know if you are plugged into shoreline which would have the battery charger running. You could have poor connections along the way or right at the batteries.

Check the voltage input right at the board with your test light and meter. See if the test light goes dim for a second when it tries to light.

Your old board may be ok and the new board is just acting a bit differently.