I have a natural gas furnace that won't stay on. The pilot is lit and
the burners come on, a few seconds later the fan starts and runs for no
more than a minute and then it stops. The burners sometimes go out
before the fan stops or the fan never comes on at all. I can turn the
fan on at the control and have it run with out a problem, but that is
just circulating the air and not heating it. I think the fan is
controlled by it's own thermostat. Once the thermostat in the house
starts the burners a thermostat in the furnace turns on the fan when it
reaches a certain temp to blow the warm air through the ducts. Does
this sound right? Could this be where my problem lies? Could it be as
simple as a loose wire to that particular thermostat? We had a service
guy come and look at it and tell it us it's just old & inefficient and
it'll be about a grand to replace. I had the Gas Company out last week
to replace my meter with a higher flow model due to a recent swimming
pool installation. He checked all our gas appliances after the
replacement and everything including the furnace worked fine. The
furnace started having trouble over a week later, I doubt the problem
was caused or triggered by anything he did since the furnace worked
fine for over a week. Help a cold Californian please, yes it gets cold
in CA. I'm in SoCal, high desert area, last weekend we had single digit
temps (rare). Thank God it worked then.
in buffalo ny: on my 1990 gas boiler, the spark ignitor is also a flame
sensor. on mine i have to see that pilot flame wraps around the
sensor/ignitor/thermocouple properly after the ignition spark and
during the main burner on. and exactly according to the specifications
of the manufacturer. i keep my manual by the boiler.
if there is a good flame then i replace the ignitor/sensor.
if i have insufficient flame, i clean out or replace the pilot
There's a safety thermostat in the furnace that is intended to shut down
on furnace overtemperature. If yours is failing or has a loose connection,
it might be the culprit. Or you could just replace the whole furnace.
Or move (further) south.
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