Furnace Cleaning in San Mateo, CA

What a furnace cleaning actually involves in San Mateo homes

Power goes off at the disconnect first. Gas valve to off. Then the burner compartment opens. Burners come out and get brushed and vacuumed. The flame sensor gets polished with a fine abrasive pad, not sandpaper. We inspect the heat exchanger with a mirror and light. The inducer, pressure switch tubing and drain get checked while the access is open.

The blower is the dirty part. On many closet and crawlspace furnaces here the wheel has to come out to clean it properly. Dust cakes into the leading edge of each blade. A caked wheel moves less air and the furnace runs longer to satisfy the thermostat.

Where that dust comes from matters more than the cleaning. Older ranches with undersized returns pull air around the filter instead of through it. Gravity-conversion systems reusing oversized galvanized trunks move slowly and let grit settle. Attic flex that has pulled loose at a boot feeds the blower unfiltered attic air. Wildfire smoke seasons leave fine particulate that returns fast.

We say so when cleaning alone won't hold. A cracked heat exchanger ends the conversation. So does a disconnected return plenum. Fix the leak, then clean, or you repeat this next year.