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Why Is My Heating System Making Banging Noises?

Posted: November 16, 2015

Hearing noises

Posted: November 16, 2015
Posted by: Larry Grier, Service Manager

If you have a closed loop hot water boiler, this is a fairly common situation. Similar to a radiator in your car, your boiler is filled with water. When air leaks into the system, the pressure rushes through the pipes, creating a banging noise.

Air can be drawn into the system in several different ways: defective valve, broken bleed screw, pressure leak, and previous pipe repair. Another possibility is due to an expansion tank. Because water expands when heated and contracts cold when cooled, extra space is needed to store air. This is called an expansion tank. Air can be drawn back into the boiler from this piece.

An oil burner with a partially blocked nozzle can exhibit some outward signs that you should be aware of. You may notice an odor because fuel is dripping out of the nozzle after shutoff which would result in unburned fuel in the combustion chamber. When the system fires up, this would cause a small boom or rumble which needs to be addressed. Other reasons for banging noises can include dirty burners. Dirt on the burners delay the burners from igniting, causing an excess of gas to build up. So when the gas does finally ignite, you’ll hear a loud bang. You should never ignore this noise because these small explosions could crack the heat exchanger (which is expensive to repair).

Other sources of banging can be expanding and contracting air ducts — metal under pressure.

Finally, the noise could involve your blower wheel; the blower wheel came loose from the motor shaft and is now hitting the blower casing, or the motor mount broke, causing the whole blower assembly to drop and hit the housing.

There are a variety of things that can go wrong, and even if the noise is minor right now, that doesn’t mean you shouldn’t get it checked out. To prevent costly problems, contact us, or call us at 888-607-2621.