Problem with MGHA
Posted: Tue Oct 19, 2010 8:04 am
Help!
I light the pilot...no problem...flip on thermostate and furnace fires...no problem...the house heats up fine a couple of times but then something triggers the pilot/gas valve to go off.
Tested the thermocouple and it clicks at 2 minutes. That seems long but it works.
Tested the transfomer and it reads 27 volts at output
Fan switch works but delays by about 3 minutes after thermostate calls for heat and after burners shuts down. But not 100 percent sure is shuts off evertime consistantly at 3 minutes
The furnace sometimes works for up to 3 or 4 hours at times before the gas pilot goes out...and then other times it lasts just one heat cycle.
I also tried boosting up the pilot flame a bit to eliminate draft issues. Wind doesn't seem to play a role.
I have not ruled out the fan switch but....if the fan switch fails to shut off after house reaches temperature and keeps running is there any reason why the gas valve would call to close??? The gas valve should only close if the termocouple senses no flame, right?
How do you test the gas valve??
Any ideas?
I light the pilot...no problem...flip on thermostate and furnace fires...no problem...the house heats up fine a couple of times but then something triggers the pilot/gas valve to go off.
Tested the thermocouple and it clicks at 2 minutes. That seems long but it works.
Tested the transfomer and it reads 27 volts at output
Fan switch works but delays by about 3 minutes after thermostate calls for heat and after burners shuts down. But not 100 percent sure is shuts off evertime consistantly at 3 minutes
The furnace sometimes works for up to 3 or 4 hours at times before the gas pilot goes out...and then other times it lasts just one heat cycle.
I also tried boosting up the pilot flame a bit to eliminate draft issues. Wind doesn't seem to play a role.
I have not ruled out the fan switch but....if the fan switch fails to shut off after house reaches temperature and keeps running is there any reason why the gas valve would call to close??? The gas valve should only close if the termocouple senses no flame, right?
How do you test the gas valve??
Any ideas?