I have an Earth Stove TG440. It's a gas stove/room heater with
artificial logs. The pilot lights fine. When flipping the on/off switch
to on, the stove burners don't come on. I had this problem last year and
had a furnace repairman in to fix it. It worked fine right after that.
Now this winter it doesn't work again. So I figured I'd troubleshoot it
myself before calling the repairman.
The troubleshooting guide says to short across the switch to see if it
is a faulty switch. If that doesn't work, then short across the contacts
at the gas valve to see if it is faulty wiring from the switch to the
valve. I couldn't figure out how to easily get to the underside of the
switch, so started by shorting across the contacts on the valve. There
was a click, and then the burners lit! I proceeded to disconnect the
wires to the switch and hook up two wires to a thermostat that was
originally installed by the stove dealer, then later disconnected. The
thermostat didn't cause the burners to light. No click, no nothing. So
I disconnected the wires from the back of the thermostat and shorted
them. I can hear the click like the gas is going to come on but then the
pilot promptly goes out. It doesn't look like it's being blown out. It
looks more like the gas to the pilot is just cutting out. Shorting
directly across the contacts on the valve is now doing the same thing.
Click, then the pilot goes out. The burners only lit the one time
earlier when I shorted across the contacts on the valve. Now just click,
and the pilot goes out.
I tried adjusting the pilot screw to increasing the gas to the pilot a
little bit. Didn't help. The pilot sweeps over one side of thermopile,
on about the top 3/8 to ½ inch. It doesn't engulf it though, just sweeps
over one side. One diagram in the manual shows the flame sweeping over
just like it is physically doing. Another diagram shows the flame
engulfing the top 3/8 inch or so of the thermopile. I don't have a
voltmeter or would check the millivolts from the thermopile. I may
borrow or buy a voltmeter to check this. I'm thinking maybe low
millivolts from the thermopile since neither the switch nor the
thermostat produces a click (valve on) but shorting the wires does. The
low voltage from the thermopile may not be able to overcome the added
resistance of the contacts in the switch or thermostat. The manual says
the thermopile should read 125 millivolts with the on/off shitch off, or
250 millivolts if an optional themostat is utilized.
There is also a ventilation safety switch in the circuit. The
troubleshooting guide indicates that if the vent is obstructed, by birds
nests for example, the burners will light but then go out after a short
time. Mine burners aren't lighting at all though.
Any thoughts on the cause of the pilot cutting out when I switch on the
gas to the burners?