water heater problem

Sounds like a bad thermostat.

Thanks for the reply. I thought that might be the problem. I will try a replacement.

It may not be the thermostat but the ECO. I would buy the kit with both the ECO and thermostat.
Make sure they are tight against the tank, first.

Is there a reset function on the water heater itself. These are usually two buttons on the center of the user panel - next to the burner / high pressure valve. They would be clearly visible after removing the outside cover. I would try this first. My suggestion.

There is no reset buttons on this particular water heater. Thanks for the suggestion.

Your Atwood uses one set of t-stats for both electric and propane operation

They are under the foam cover in outside compartment

Brown wires to/from normal t-stat (preset to OPEN at 140*F)
Red wires to/from ECO (high temp t-stat---preset to OPEN at 180*F)

If t-stats are not held tight against tank wall they can not properly sense the correct temp.

They are held against tank with a plastic washer that presses down a spring and then held down with three small tabs. I hate the design. (Suburban uses a bracket that screws down)
Problem is probably with the normal t-stat not tight against tank.

Thanks for all the suggestions. I ordered the combo pack today. I had a little trouble getting a couple of the wires off. I didn't want to break any. Hopefully the new set will take care of the problem. I will make sure they are both tight against the tank.

Just an update. I replaced the old Tstat and ECO with a new kit. After heating the water up, it seems to be working fine. I don't notice the heater coming on every few minutes. Thanks again for all the great suggestions.

You found it. the T-Stat shuts the heater off when it's hot and turns it back on when it starts to cool.. Sounds like yours got old and the "Delta" was gone..

Some electronic T-Stats (not compatible with that water heater, or, far as I know, any water heater) have adjustable Delta (The difference between turn on and turn off) but on that one it's factory set... And it appears that old age changed it.