Water heater problem diagnosis

et2 wrote:

Artum Snowbird wrote:
My problem was the heat sensing melting fuse built into the wire that crosses in from of the burner tube outlet. It was a very weak connection. I didn't know what it was there for at first until I looked it up and realized it was there to shut off the burner if it sensed a fire in the tube and melted. When I jumpered it out to test it, the heater worked fine.

What did you do to fix it, replace or clean and crimp? I know what your talking about. My understanding is it's either working or blown and that stops all operation until replaced.

If I recall correctly, it was covered with some protective sleeve, maybe heat shrink. I think I removed that, then cut off the corroded connection and replaced the heat shrink.

Ok I have not seen that heat fuse on my Atwood I do have a pair of theromstats but I'd have to look for a heat fuse

When the T-Stat calls for heat the control board opens the gas valve and starts the spark generator
Flame results and heats a metal rod (it is in fact adjustable part of the "Spark Generator: one common issue with both Water heaters and furnaces is the SPARK GAP is too big and the spark can not jump the gap but you said yours lights so that's not Likely your problem.
When hot this rod generates about 0.480 volts

The same wire that carries close to 1000 volts to make it spark, now carries 0.480 volts (Less than 1/2 volt) back to the control board.. Imagine what happens to the sensor chip on the control board if the switch happens when the spark generator is at the PEAK (Around 1400 volts).. OUCH.

Once the flame sensor chip sees voltage it continues the flame. IF IT DOES NOT see voltage within a few seconds it shuts down and tries again So many (3 I htink) tries it FAULTS.

Finally when it is hot enough the T-Stat opens and the control board shuts the burner down.. OR if the T-Stat fails the EEC (a 2ne t-Stat) opens and shuts the system down with a FAULT light, .

I would start by checking all connections. especially the ECO connections

Artum Snowbird wrote:
My problem was the heat sensing melting fuse built into the wire that crosses in from of the burner tube outlet. It was a very weak connection. I didn't know what it was there for at first until I looked it up and realized it was there to shut off the burner if it sensed a fire in the tube and melted. When I jumpered it out to test it, the heater worked fine.

What did you do to fix it, replace or clean and crimp? I know what your talking about. My understanding is it's either working or blown and that stops all operation until replaced.

My problem was the heat sensing melting fuse built into the wire that crosses in from of the burner tube outlet. It was a very weak connection. I didn't know what it was there for at first until I looked it up and realized it was there to shut off the burner if it sensed a fire in the tube and melted. When I jumpered it out to test it, the heater worked fine.