FURNACE PROBLEM · DIAGNOSIS GUIDE
Different noises point to different problems. Use this guide to figure out what's happening before you call.
Banging or booming at startup = delayed gas ignition, which is a safety concern. Stop using the furnace and call us same-day. Rumbling or signs of cracked heat exchanger = carbon monoxide risk. Get a working CO detector near sleeping areas if you don't have one.
Delayed ignition — gas builds up before lighting, then ignites with a small explosion. This is a safety concern. Stop using the furnace and call us same-day.
Often a dirty burner, sometimes a cracked heat exchanger. Cracked heat exchangers are a carbon-monoxide risk — get the furnace inspected immediately.
Failing ignitor or control board trying to start. The system is going through its startup sequence repeatedly without success.
Often a duct or return-air issue (undersized return, closed registers, partially blocked filter). Less serious than the others but worth fixing — it's costing you efficiency.
Blower motor bearings are failing. Replace the motor before it seizes and damages other components. $400-$700.
Loose panel or duct connection. Usually cosmetic but easy to fix.
Banging or rumbling noises can indicate cracks in the heat exchanger, which can leak carbon monoxide. If you don't have a working CO detector near sleeping areas, install one today — this is the most important $20 you can spend on home safety.
If your CO detector goes off, leave the house and call 911. Don't try to ventilate or wait it out.
“Loud banging at startup. They came out, found delayed ignition due to a dirty gas valve, cleaned it, and the noise stopped. Half what another company quoted.”
Greg P. · Stillwater, NJ
Same-day appointments in Sussex and Morris counties. 24/7 emergency dispatch — answered around the clock by a real on-call technician.
98 Morris Turnpike, Newton NJ · NJ HVACR Lic #19HC00108700 · Since 1999
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