Help w/ Water Heater

Ummmm....just a thought since no one else has mentioned it...is there water in the water heater tank? If the unit has been winterized and the valves are still closed, I believe that the burner would shut itself down because of an overheat condition caused by an empty tank. This is just a guess since I live in SoCal and have never needed to winterize my rig, nor does mine have those WH bypass valves, but...

If it is lighting off, it is not the thermal fuse.

If it is staying lit for exactly 30 seconds and then cutting out, your problem is the circuit board.

If it is staying lit for random amounts of time, the problem is in the flame sensor.

Mississippi Granna wrote:
Thanks for your help. Is there a simple test to determine if its the circuit board

. There is a simple test for the board. Go to the Attwood web site and they show the test. Also if it is not the potted board you can remove it and look at the back side for burned tracks.

I had very similar behavior in my DSI model water heater. I replaced the flame sensor and no dice. I replaced the controller board with a DinosaurElectronics version and it has been happy since.

Jose

Dusty R wrote:
The flame detector is NOT a thermocouple, it is just a rod/electrode, flame/fire is a conductor. Thus there is a current to ground through the flame rod which the circuit board senses. So a dirty rod or if the rod is not in the flame. Will it to shut down.

Dusty

Failure I've seen on three different Atwoods has been a break in the high tension wire, inside the insulator. Spark can jump across the break, but when it comes to measuring current at low voltage, it is an open circuit. Could be easily checked with an ohmmeter.

https://www.youtube.com/watch?v=8XucClM6bJQ

Demonstration of how to test the flame detector.

The flame detector is NOT a thermocouple, it is just a rod/electrode, flame/fire is a conductor. Thus there is a current to ground through the flame rod which the circuit board senses. So a dirty rod or if the rod is not in the flame. Will it to shut down.

Dusty

I'm with tatest on this one. We are all just guessing based on experience but if it really is running for 30 seconds... as in the burner lights and begins heating... then the igniter is working. The gas valve is being opened so the circuit board is doing at least part of its job. The other part of its job is to shut down the LP if it did not light so you don't fill the bay with LP. It's acting like the flame detector has failed. The board is not receiving the flame signal so it is cutting off the gas for safety.

Personally I would replace the flame detector which is a thermocouple first. It's cheap and a likely failure point since it is exposed to a direct flame often. If that didn't fix it, I would replace the circuit board.

Could also be a fault in the sparker/flame detector, which wears out from exposure to the heat. It can spark, ignite, yet have too much resistance to carry the tiny current that tells the circuit board the flame is going.

More likely than a failed circuit board, and a much cheaper part to replace.

As others have said, circuit board or thermal fuse. It will be obvious if the thermal fuse blew (because it will look burned), and the circuit board is an easy swap.

I carry an extra board (and fuse) with me in my spares kit. They don't take up a lot of space.