Gas furnace question

A family member’s home…

When the thermostat calls for heat the draft inducer fan comes on but that is it…it runs continuously and nothing else happens…the igniter doesn’t glow, the burners don’t ignite, etc.

Chimney’s not blocked and the vacuum hose isn’t cracked.

Any ideas before calling a service tech?

Thanks.

It’s not making the diaphram switch that proves that the draft fan is operating - could be a bad diaphram, or if it’s a condensing furnace, the drain line could be clogged, and the trapped water could be slowing the fan enough to keep it from making the switch.

Thanks Andrew, I’ll check the hose and diaphram areas again.

It is not a condensing furnace…it’s 80% plus Rheem about 20 years old.

I’m off and will check back later.

Could be the draft pressure switch, the pickup port for the draft switch restricted or plugged, inducer wheel for draft switch dirty or rusted away, inducer running slower either through bad bearings or a lower voltage being applied or a split in the heat exchanger.

Thanks, Gary, I’ll check what I can this afternoon.

And, when all is said and done and a qualified individual services and repairs as necessary - remind them that gas fueled combustion equipment should be serviced at a period not exceeding 2 years. Maybe something just gave up the ghost but it does not sound like a routine maintenance program has been in place.

It has been maintained but thanks for the thought.

Does the gas control valve make a clicking noisy?

Call a qualified tech to make sure it is safe to operate rather than resetting any safety for sake of thinking its safe to operate.