Nov
04
Pilot Won’t Light On My Heil 75000?
ByI can light it manually by turning off the switch on the side of the unit and the gas valve then back on but after the house reaches the temp it goes out and won’t relight by itself. Just had the techs who put the ten year old furnace put on a new gas valve and hot surface ignitor on it January 2006 something goes bad on this furnace every year HELP! PLEASE thank you!
2 Comments
November 5th, 2009 at 4:14 am
By shutting the power off & back on you are resetting the time out feature built into electronic ignition furnaces. If its lighting then the ignitor and gas valve are working properly. It sounds like the control board is likely bad. Try this. Turn on the unit and stay near it with the panel off, have someone turn down the thermostat until the burner goes out. Let the fan run its course & then have them turn the thermostat up to call for heat. Check to see if the ignitor is coming on & if so listen for the click when the gas valve opens. If the ignitor does not come on without resetting it & or the valve doesn’t open then the board is bad.
If the ignitor works and you can hear the gas valve open and gas flowing to the burner then the burner is dirty and or the new ignitor has been repositioned improperly. Most untis will try to light 3-5 times then time out for 5 minutes.
The control boards range from 50-125 dollars.
November 5th, 2009 at 5:59 am
probally a bad circuit card but there are several safetys on this heil. each time it goes to a call for heat the circuit card starts the combuston fan first. then it checks for fan proving switch closure. however the switch must have checked open first otherwise the circuit card will assume the switch is stuck closed. if all this goes well the 30 second purge goes on. after this and if all roll out switches are closed it will send power to the hot surface ignitor. it senses resistance changes as the ignitor gets red hot. once resistance is right it turns on gas and the furnace lights. if the furnace senses the flame it will continue to allow gas flow until the call for heat is stopped by the t stat. You need a good a/c heat amn who knows all this otherwise they just are parts changers.