Originally Posted by shrimper
If the control board was fried wouldnt it affect the 120 v side as well?the t sat for 120v is fine as i tested it for continuity but the 12v gas side was burned out .
As I've said before-- and LOTs of folks have trouble with this...
The 120v AC heater is TOTALLY INDEPENDENT of the LP gas burner and
They are not connected anywhere at all period.
The ONLY thing the electric and gas heat have in common is the tank
of water they are trying to heat.
They have separate power sources and separate off/on switches and
separate T-stat/hi limit switches.
There is NO control board for the AC electric heater.
It's simply a heater- inside the tank, a thermostat/hi limit switch- outside
the tank and a black off/on rocker switch which is usually found in the
outside hatch near or even behind the gas burner tube.
OK so you now have electric hot water working OK yes???
You have it shut off so the tank is cold-- good.
You say the gas t-stat was burned out???
Have you replaced it??
Have you tested for 12v at one end of the t-stat???
I guess you do have that because you said earlier that you jumped
across the gas T-stat and the burner tried to light-- you heard and
or saw the spark jumping???
IF you had spark all you need is for the gas valve to open.
You need to put a meter across the wires for the gas burner valve and
see if you have voltage AT the burner valve while it is sparking.
Set your meter on DC scale and you should find 12v across the gas
valve while it's sparking.
1-- If you do have voltage but don't smell gas the valve is stuck or burned out.
2-- If you don't have voltage at the gas valve this would indicate a probable
bad control board.
I think you have narrowed it down to 1 or 2.
It's awfully hard to trouble shoot your water heater from my basement but
that's my opinion.
I'm not gonna tell you to go messing with the LP gas part of the system.
If you mess up and have a leak or other problem that causes you a fire
or other grief I don't want the blame!
I'll tell you that I'd not be afraid to continue but I've got 37 years of
industrial maintenance under my belt and feel confident doing that kind
If you don't feel confident, it's getting closer and closer to time to go
to a repair shop.