Noise in Hot Water Furnace Pipes

Hammering

• If the hot water sounds like a hammering noise, the water pressure in the pipes is likely accumulating and causing vibration in the pipes when released. One way to reduce this sound is to secure the pipes along the pipe routing to help reduce vibration. Another method is installing a water hammer arrester, which has a rubber diaphragm that moves back and forth to reduce the water pressure energy and noise. This mechanism should be installed by a plumbing professional.

Sediment

• Accumulation of sediment inside the water tank can create noise because the sediment or mineral scale interferes with the heat transfer. Disconnect power and turn the gas setting to the lowest point. Turn off the cold water supply and attach a hose to the drain valve, running the other end of the hose to a large bucket or drain. Open up a hot-water faucet near the hot water furnace and then release the drain valve. Let the tank drain out then shut off the drain valve and turn the cold water to further loosen up sediment in the tank. The tank will fill partially and then drain a second time. Repeat until the drain water runs clear and then close the drain valve and disconnect the hose. Open the cold-water faucet and allow the tank to fill back up and then close the hot-water faucet when water begins to flow from the hot water faucet. Restore power and gas to the unit.

Worn Bearings

• The bearings inside the hot water furnace may get worn over time and begin to make noise when the water is flowing. This might sound like a banging or knocking sound and is a common problem. Contact the furnace manufacturer or another qualified service technician to inspect and repair or replace the bearings if needed.

Pump or Motor

• Loud grinding, squealing or whining noises typically indicate that there are problems with the furnace pump or the motor. Over time, the pump and motor can wear out, become damaged or fail and cause extremely loud operation. An air vent might need to be installed to reduce air inside the unit and prolong the pump life. Contact a service professional for assistance.