Atwood Water Heater; No Spark, No Gas

[retmotor]

The Internet stinks for actual diagnosis of this problem. It's all, replace... replace... replace... No diagnostics.

The water heater has no spark and no gas, intermittently.

Power is good - 13.8 volts
The coach switch checks good for power (13.8v and continuity).
13.8v to the thermostat
13.5-13.7v after the thermostat (vascilates)
LP gas pressure is enough to operate the furnace and the stove, so it's unlikely that's the problem.

here's the intermittent part:
0 or 13.8 volts at the incoming lead to the ECO (from the circuit board). It was a consistent zero until I jumped power to to bypass the ECO. Bypassing the ECO allowed the heater to operate. After I removed the bypass, for some reason I had power again.

All terminals have been checked for connectivity and they all look good to me. Of course the thermal fuse is good too.

Before I order one, does anyone think it is NOT the circuit board causing the intermittent power? I do so hate to just throw money away replacing parts.

[jesilvas]

If we're diagnosing: what is actual LP pressure? "Enough" is a guess, however, your guess is probably right.
I think Dinosaur boards has board testers, but never used them. If you are not getting power out of the board, that's where the issue is. You do have a fuse I think. Is that fuse good, fuse holder good?

[CLIFFTALL]

Atwood techs are very available and may be able to assist. Here's a # I've used successfully.

574-264-2131

[Sammie]

retmotor, If you can access the back side of your water heater, check to see if the ground wires are attached securely. On my 10 Gal Atwood in my 2006 Winnebago Journey, I found that there are two 1/4 inch studs sticking out of the back of the water heater with ground wires attached that had become so corroded that the ground wires were barely making contact.

This picture shows one of the ground wires hanging loose along with broken stud after I attempted to tighten it. Once I found and reconnected to a good ground on the tank everything worked great.



Sammie

[mgscott4]

It sounds like to me the ECO is bad or you had (have) a dirty connection. Clean the connections even though they look good or replace your ECO.

And clean the green ground wire down near the gas valve, the ground has caused me problems in the past.

[EngineerMike]

I'd undo, clean & remake all connections before ordering a new board. Could be the board but it sounds like a connection.

[patsikes]

We just had to replace the main board on ours. It would not spark or open the gas valve. If you pushed on the "potted" board in the center the valve would click open, an obvious short in the board. I ordered an installed the new board and it all works great now...

[retmotor]

Originally Posted by jesilvas

If we're diagnosing: what is actual LP pressure? "Enough" is a guess, however, your guess is probably right...

I don't have a pressure gauge, and it does work intermittently, so I'll address that as a potential problem when and if I cannot find another problem.

I did see that Atwood has a diagnostic tool for the circuit board. I would assume that to mean a multi-meter won't get the job done.

[retmotor]

Originally Posted by Sammie

retmotor, If you can access the back side of your water heater, check to see if the ground wires are attached securely. ...

Thanks for that. It sounded like a good possibility. I took apart the cabinet only to find water connections though, no electric whatsoever. In your picture it kind of looks like you have the thermostat or the ECO pictured. Both of mine and the unit ground are accessed from the outside.

[retmotor]

Originally Posted by Clifftall

Atwood techs are very available and may be able to assist. Here's a # I've used successfully.

574-264-2131

Thank you. I will likely give them a call when the rain lets up. What is it about calling a tech though -- it's like asking for directions -- the ol' pride takes a hit.

At this point I've double and triple checked the connections. I do not see a problem with any of the electrical connections.

[Sammie]

Originally Posted by retmotor

Thanks for that. It sounded like a good possibility. I took apart the cabinet only to find water connections though, no electric whatsoever. In your picture it kind of looks like you have the thermostat or the ECO pictured. Both of mine and the unit ground are accessed from the outside.

My WH is equipped with an electric heating element which is what you see in the picture on the backside of my tank. More and more, it sounds like your going to need a new circuit board.

Sorry,
Sammie

[94-Newmar]

Originally Posted by retmotor

0 or 13.8 volts at the incoming lead to the ECO (from the circuit board). It was a consistent zero until I jumped power to to bypass the ECO. Bypassing the ECO allowed the heater to operate. After I removed the bypass, for some reason I had power again.

ECOs are very simple switches. These can be tempermental. It is possible that it has failed and by bypassing it, allowing the unit to come up to temp again, that the heat (thru expansion/contraction) has allowed the internal contacts to begin touching again. Since it's a very inexpensive item if it were me I would replace it. 2nd thing to do occasionally is to slide the large wiring connector from the control board and using a pencil eraser gently clean the copper contacts/traces on the control board that mate with the connectors.

[retmotor]

The rain didn't let up so I didn't call Atwood. I took the TW200 motorcycle out for a ride in the desert instead (priorities). Weird I know, but I do love a ride in the rain.

Thanks, 94-Newmar. I was thinking about that last night. And then I got to wondering if the fluctuating voltage on the backside of the thermostat indicated a problem with the thermostat that might cause this problem. I'll have to call Atwood or maybe just order the thermostat and the ECO. They come as a couple, apparently, and they are twelve years old (probably).

I did the trick with the eraser and checked for fresh scratches. I have good contacts to the board.

And thanks, Sammie, I didn't even think about an electrode. It's not something this water heater has.

[retmotor]

The Atwood tech says -- (long dramatic pause) -- circuit board.

I asked her if she was really sure, because it was the most expensive part to replace and even so that didn't change her mind a bit.

Now let's see if I can find a decent price on a circuit board...