intermittent flame/gas cut off

rayleland

I'll do my best to provide all details. This is with regard to a Miller gas furnace; we're using a honeywell digital thermostat (t3200). The symptoms are as follows: The thermo triggers the furnace to power up; I can hear the gas kick on and the flames start blowing, then the gas kicks off prematurely. The power stays on as the furnace "re-trys" this approx. 4 times; finally it just powers down. The fan never kicks on, producing no heat through the house. This happens intermittently. I suspected the thermostat, as the furnace seems to have all the power/gas that it needs. So, I replaced the thermostat. Now same problem. The furnace is only about 8 years old. We generally program the thermo to 72 degrees. Any ideas?

rakes9720

Clean the flame sensing rod in the furnace. It is dirty and can't sense flame, so it shuts the gas off in case it were just spraying unignited gas into the air.

rayleland

Okay. What would I use to clean the sensor? Much thanks.

rakes9720

Steel wool will work. Just turn of the power first, and remove the rod if you can.

harleyrider

If you dont have steel wool, you can also use emry cloth or sand paper

rayleland

Done. So far that seems to have done it. As it was intermittent, I'll be keeping an eye on it for the next 24 hours. Thanks a lot for the help.