A Whistling Sound on My Harman Boiler

Air Flow

• Harman boilers require a steady flow of air from their supply vents for necessary combustion. If the vent becomes clogged, the boiler will not be able to burn efficiently. The strain of the supply vent and the poor burning conditions may be responsible for the whistling noise you hear. Double-check the supply and exhaust vents for clogs that could be at fault. A thorough cleaning should solve the problem.

Fuel Issues

• If the whistling is coming from the combustion chamber, the problem may be the fuel you are using. If the pellets or wood you are burning have too much moisture, they may produce the whistling sound as they burn. Clean out the combustion chamber thoroughly and use only dry fuel suggested by the Harman manual. Pellet boilers are not designed for wood, and vice versa. You may be able to stop the sound by using proper fuel.

Exhaust Issues

• While pellets do burn clean, burning them produces exhaust. The carbon from this exhaust can layer the exhaust pipes of your boiler over time, creating portions of dense creosote. This creosote can affect heating patterns and air flow, and may even catch on fire, creating the whistling noises you hear. Creosote build-up in particular and deposits in general are serious issues and you should remove them as soon as possible with a thorough cleaning, using a solvent if necessary.

Metal

• The metal vents and exchangers that your boiler uses expand and contract with sharp temperature changes. If your boiler is outdoors or in a cold location, the whistling you hear could be the metal expanding as it is heated up by the fuel. If the whistling stops after the boiler has been operating for a while, this is a likely cause and does not need extra attention.