I have a Rheem furnace that is gas and outside. Here is the issue. The furnace will be working fine and then quits. Today I came home and it was 60 in the house. This has happened several times this year.
When I switch the themostat from off to heat there is an ignitor that lights the pilot. All this works just fine but no gas comes on to the burners.
What tells the gas valve to come on when the pilot is lit?
1. the t stat calls for heat
2 usually the inducer mtr comes on next
3this has to PROVe. by either a pressure switch or sometimes a centrifigal switch
4 after that, then usually the ignitor comes on
5 then after it is hot enough, the gas valve opens.
so.. if the ignitor does come on and glows etc.. the gas valve "should" come on. do you have a meter by chance? if you do like DIY's you should get one if you don't already. I have bought cheap ones before, kinda spur of the moment needed 1, and mine wasn't around.. for 20 bucks and they still work fine! IF YOU GET 24 VOLTS AT THE GAS VALVE AND IT DOESN'T OPEN ( FIRE) THEN IT IS THE GAS VALVE. IF YOU DON'T GET 24 VOLTS, IT IS IN A CONTROL. whoops! just noticed I hit caps! sometimes those ignitors LOOK hot enough, but are not hot enough to PROVE they are on.. if you replace that ignitor, do not touch it( the end) (treat it like a halogen bulb)
Yes I have a meter but don't for sure know where to check for the voltage on the gas valve. As far as it being hot enough the ignitor lites a pilot lite and there is a metal shield? over it that get red hot. I keep looking for something like a thermo-couple that would send a signal that says the pilot is lit so it is ok to turn on the gas but I don't see anything like that.