Gas and Oil Home Heating Furnaces - Heat not working on thermostat

We replaced our thermostat upstairs 2 months ago because the heat was not coming on even though the flame on the furnace was lit. Now the heat has stopped working again. The air conditioning works but absolutely nothing happens when I flick the switch to heat on the thermostat. It's a Honeywell thermostat and GE furnace. The prior thermostat was Honeywell as well.

When you say flame on the furnace do you mean the pilot light? Check low voltage wiring at both the thermostat and furnace ends. Make sure you have good connections and that the wire is not frayed, cracked, burnt, etc. Try wiggling the wire where it goes into the furnace and see if you get any response. If you have the Honeywell "round" thermostat, turn it to heat and increase and decrease the settings and see if the mercury is making a small spark when the contact is made inside the small glass tube. Try these tricks and we can go further if needed. If this does not work, try to get the gas valve make and model and send it in your next reply.

and get back to us.Remove tstat,take red and white wires twist them together.If heat starts problem is in tstat.Also make sure pilot is lit.PDF

It ended up being a problem with the pilot sensor. A wire was sticking out too far. It’s fixed now. Thanks for the tips.