Burner cutting in and out during startup of gas heater
Model Number: 48SX-400-074 Brand:
More than 10 years
I have a Carrier gaspack. Carrier is not listed in the "Brand" pulldown menu for this forum for some reason ... wonder why?
Anyway, the burner on my furnace is cycling on an off a few times before it stays lit. Once lit, the furnace works properly.
The problem seems to occur mostly after the furnace has been down a while, such as in the morning when when my programmable thermostat turns up the heat for the day. The furnace is outside my bedroom room and I can hear what it's doing. First, I hear the sound of the burner coming on. In normal operation this sound would continue a few seconds after which the blower would come on. But instead the burner turns off (gets quiet).
After a few seconds I hear the burner start again. This time it seems to say on a little longer. But then it goes silent again. After a few cycles of the burner cutting on and off the blower also comes on, but not for long. Everything goes quiet again. Then I hear the burner start again.
After several more cycles the burner finally stays on. The blower comes on and stays on until the house is warm. For the rest of the day everything seems fine. The furnace seems to cycle on and off properly. I fear that something is waiting for the coldest day of the year to quit completely.
I'm not a technician but I've done some reading. My theory is that the flame sensor may be getting weak. This would cause the computer to shut the gas valve off if the flame sensor's signal does not appear in time. Maybe after a few tries the flame sensor finally gets hot enough to deliver a solid signal. Then everything works fine for the rest of the day. But this is just what it sounds like to my untrained ears. I could very likely be completely wrong. Do flame sensors get weak before failing completely?
Any comments are greatly appreciated.
Thanks for taking the time to consider my situation.