What To Do When Your HVAC Has a Rattling Noise

What’s that rattling noise in ducts you’ve been hearing? It seems like once you start to notice it, the sound gets louder and more annoying as time goes by. The network of ducts inside a house is typically metal and provides a suitable chamber for amplifying and distributing sound throughout the house. That makes it even harder to track down as a rattling noise in ducts may actually originate far from the vent where it seems to come out. 

Because the ductwork in a typical house is very difficult to access for most homeowners—routed through the attic, crawl space and inside wall voids—professional inspection by a qualified HVAC service technician is usually required to identify, locate and resolve sources of noise emanating from ducts.

Potential Causes and Cures

Blower Fan Issues

Defective moving parts in the blower fan assembly installed in the indoor air handler may transmit noise throughout the ductwork. This can include a defective fan pulley, worn motor bearings, or a loose motor mount.

Rattling Vent Grills

Noise coming from the ducts may actually be caused by vent grilles that  have loosened. Airflow passing out of the duct causes the metal grille to rattle. Checking the vent grilles and tightening the securing screws if any are found to be loose is one DIY procedure that may eliminate unwanted sounds.

Foreign Objects Inside Ducts

Any loose objects inside the ductwork may react to the movement of airflow by rattling or banging. These may include internal nuts or bolts that have fallen inside the duct, objects placed into vents such as marbles, tools inadvertently left inside the ductwork, and so forth.

Loose Duct Spans

Ducts routed through the house are typically anchored to wooden structural framing. If these attachments loosen over time, a span of unsecured ductwork may make a rattling noise when the system is running as it shakes against the wooden structure.

For professional service to track down and eliminate a rattling noise in ducts, contact Energy 1 Heating & Air Conditioning.