I have z Tempstar - I think it's an older ps80 - furnace in my
basement. Over the weekend, it has been functioning irregularly.
Please excuse any misuse of terminology - I'm among other things a
mechanic, but not an hvac guy.
On the surface, somtimes the heater would go on and blow nothing but
cool air around. So I had a look at the aggregate.
Correct me if I'm wrong, please: The proper order of events is this:
1). inducer motor starts up
2). heating wire glows
3). pilot light ignites on heating wire
4). two gas jets ignite on pilot light
5). fan wheel come on.
Most of Saturday, the two gas jets did not ignite, and I think it's
safe to assume, there were no gas jets (the pilot was lit). However,
I found that by opening the blower cabinet and pressing the 'dead-man'
switch, and then going through the ignition sequence, I could always
get them to ignite eventually (after maybe 8 or 10 tries).
The furnace worked fine all of Sunday, but failed one single time to
ignite this morning (Monday).
Hypothesis 1). The valve is sticky or defective
Hypothesis 2). The sensor (bi-metal?) is sticky or defective.
Does this sound reasonable? Or are there better explanations?
Particularly, does this sound like something that is likely to recur
often that I need to do something about, or might there have been,
say, some impurity or something temporarily clogging up the works?
Thanks for any help. Frank