Strange noises from your gas heater should not be ignored. Although most noises are benign or only mild issues, some can be quite dangerous.

1. Clanging

Clanging noises can be quite loud and alarming. Sometimes these noises only surface when your heater turns on, while in other cases they may continue for the entire running cycle. Noises that appear at startup are often just the result of ductwork contracting as the heated air hits it. Continuous or intermittent clanging can indicate that something is loose in either the ductwork or the motor. Clanging is also sometimes the result of worn bearings in the motor.

2. Knocks

A knocking sound may be similar to clanging and simply caused by a loose part in the motor or ductwork. It can also be a sign that something more severe is wrong, like failed lubrication in the motor that will soon cause it to burn out. Knocking noises should always be checked out by a gas heater repair technician to ensure that major damage doesn't occur.

3. Squealing

Squealing is almost always the result of a failing belt. Some gas heaters use a belt system between the motor and fan. These belts need to be replaced periodically or the fan will fail to operate. A failed fan will trigger the emergency shut-off of the heater, and you will be left without heat until it is repaired. In severe cases, the snapping of a belt may also damage other components in the gas heater. An annual heater tune-up and inspection can catch failing belts before they begin to squeal. Otherwise, stop using the heater immediately until you can have the belt replaced.

4. Rattling

Once again, this is a problem that can often be chalked up to loose ductwork. The rattling sound will typically be mild and persist the entire time the heater is running when the ducts are to blame. Your repair technician may be able to track down the loose duct and tighten it.

5. Booms

Booms, particularly when the heater first comes on, can be the sign of a dangerous problem. Sometimes the gas doesn't ignite thoroughly, which leads to a buildup in the valve or on the burner plate. This excess gas then ignites all at once, resulting in the booming sound. If you hear a boom, shut down the heater and schedule an immediate repair visit.

Contact a gas heater repair service promptly if you hear any type of noise that is out of the ordinary.