Issue: Gas furnace hums during ignition … but blower works and output
Details: I have an American Standard GUF120D E3 H 120,000 BTU natural
gas furnace with a bonnet capacity of 96000 and a 1/5 hp motor. When
the thermostat calls for the burner to ignite, I hear an electric hum
like a motor trying to start. This continues for about half a minute
during the burn, fades out, the burn continues for a short period
longer, then the blower kicks in as usual.
I found a website with a flow chart of a common gas furnace mechanism
(http://www.mobilehomerepair.com/FurnaceFlowChart.htm ). Though this
appears to be from a site dealing with mobile homes and my home is not
mobile, I assume there are similarities. According to this chart,
there’s an “induced draft motor” – different from a blower motor –
that gets triggered in the front end of a burn cycle. If that’s what I
have, I’d venture to bet I need a new draft motor.
Anyone have sufficient knowledge to help solve this? I could use a
flow chart for my particular furnace as well. I've emailed American
Standard for a manual but if there's something on the web, I'd
appreciate being steered to it.
Maybe if you were to pick up the phone and call a local, competent(not the
lowest price), licensed, insured, professionally trained HVAC technician,
they can actually lay hands on, and find out exactly what the problem is.
OTOH, if you had a service agreement, your furnace would have already been
serviced, and the problem already solved, and repaired at a discounted rate.
Pay me now, or pay me later.