Why is my heater making a loud noise?
Clicks and whooshes are a heater's normal voice. Banging at ignition, grinding, and screeching are not. A sound-by-sound triage.
Heating systems make honest working sounds. Control clicks, a soft ignition whoosh, gentle duct pops as metal warms. New banging, grinding, screeching, or booming is not on that list. Those point to worn moving parts, ignition trouble, or another fault. Turn the system off and have it checked.
What you can safely check
- Note when the sound happens. Startup, while running, at shutdown. And which system seems to make it. A short phone recording, taken from outside the cabinet, helps the technician.
- Compare against the system's own baseline: a sound that is new, worse. Changed matters more than one that is merely loud.
- Turn heating OFF for new, severe, or worsening noises — especially banging at ignition. Do not keep cycling the system to reproduce the noise for your own diagnosis.
- Never open the furnace cabinet to chase a noise. Ignition and combustion parts are inside it.
- One smell overrides every sound check in this article: if a gas odor (rotten eggs) accompanies any of this, stop assessing sounds entirely. Leave the house and call 911 and the gas utility from outside (Q97).
What might be causing this
Learn your system's normal voice first, because every judgment in this article is a comparison against it. Clicks as controls switch. A soft whoosh when burners light. Occasional ticks and pops from ducts as metal expands with heat and contracts as it cools. Those sounds belong to a healthy system doing physical work.
New, severe, or worsening sounds are a different category. Banging or booming right at ignition deserves the most respect. It can mean delayed ignition. Gas builds up for a moment before it lights, so it ignites with a bang instead of a whoosh. That is a combustion problem. It does not improve with repetition. Repeated delayed ignition also stresses the heat exchanger. That is the metal chamber inside the furnace where fuel burns. If it fails, exhaust gases — including carbon monoxide — can leak into your air. This belongs to a pro right away.
Grinding and screeching point to the same family as their cooling-season versions: blower motor bearings and other moving parts wearing out (Q17). Running them anyway turns wear into a seized motor. In a furnace, a blower that seizes also starves the heat exchanger of airflow. That adds overheating (Q33) to the problem.
Rattling can be as innocent as a loose panel. But "can be" is doing heavy lifting in that sentence. A rattle should be confirmed as innocent, not assumed so. Panels also rattle when something inside has come loose. They can rattle when a blower wheel is failing. Has debris in its housing.
| Sound | Likely family | Action |
|---|---|---|
| Clicks, soft whoosh, gentle duct pops | Normal operation | No action |
| Bang/boom at ignition | Delayed ignition — combustion fault | Off; call promptly |
| Grinding or screeching | Motor bearings, moving parts (Q17) | Off; call |
| Rattling, new | Loose panel or part | Confirm at a service visit; off if worsening |
| Any sound + gas smell | Leak risk | Leave; 911 + utility |
When to call a professional
Call promptly for any bang or boom at ignition. For grinding or screeching at any point in the cycle. A technician will inspect the ignition sequence and burners, the blower motor and wheel. The safety controls — and confirm whether a rattle is a loose panel or something inside coming apart.
What happens next
Book a diagnostic visit. Bring the recording if you made one. It can save real time on the visit. Ask Texas Heat & Air what you will get in writing, and what your approval covers, before you book.
Texas Heat & Air next step
New bang at ignition or grinding while it runs? Heat off, then call Texas Heat & Air at (682) 438-8127.
Related Questions
Why does my heater smell when I first turn it on?What happens during a heating inspection?What should I do if I smell gas by my heater?
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- https://www.energystar.gov/saveathome/heating-cooling/maintenance-checklist — supports the inspection of ignition, blower, and control parts
- https://www.cpsc.gov/safety-education/safety-guides/carbon-monoxide/carbon-monoxide-fact-sheet — supports fuel-burning appliance safety and the carbon monoxide risk of combustion faults