Unwanted HVAC Noise

Posted 02-04-10

Our busy lives are filled with enough noise and clatter; no one wants to go home to it as well. If your furnace, a/c or duct system is making a loud, annoying racket, read on . . .

Noisy HVAC (heating, ventilation and air conditioning) equipment is not as uncommon as you might think. It’s a problem, especially in close, urban communities where heating and cooling equipment is close to sleeping areas and interior walls. There are several causes for noisy a HVAC system, some of which can be easily corrected and some that might need professional help.

Loud Operation
Some heating and cooling systems operate at high decibel levels. They’re just loud! This could be due to lower-quality equipment or the equipment simply may not be designed for quiet operation. It also may be intended for installation away from living areas where sound is not an issue. Adjustments can sometimes be made by a qualified technician to reduce the sound level, but this greatly depends upon the age, type, size, and installation quality of the existing equipment.

Equipment Vibration
Vibrating equipment may be an indication that the blower is out of balance. An out of balance furnace will act like the spinning motion of an off-balance washing machine, vibrating and creating excessive noise. Vibration of an outside air conditioning unit can be caused by improper installation. A vibration pad may not have been installed or the A/C pad is not level. A qualified technician can fix these problems.

Internal Equipment Damage
If you have metal scraping or clanging noises in your equipment, this is probably an indication of a severe problem inside your system. If you ever hear a sound, like something is interrupting the fan blade or metal scraping against metal, you should turn off your system right away. There may be internal damage to the motor or blower that could also cause further damage. Call a qualified technician to diagnose and fix the problem.

Loose or improperly installed ductwork
This is sometimes related to the distribution of air in relation to duct system design, and not necessarily a furnace or air conditioning equipment problem. You may also notice positive or negative air pressure systems, such as slamming doors when the HVAC system is in operation. If the noise if coming from a specific duct joint and you can seal or tighten the area; that will sometimes solve the problem. If the noise seems to be throughout the duct system, you may need to have your ductwork redesigned.