Does Your Noisy Air Filter Keep You Up At Night?
Air filter noise is a very common problem in residential heating and air conditioning equipment and there are many causes. Although the noise gets your attention, it may only be a symptom of a much bigger problem.
Common Causes of Noisy Air Flow
Undersized return grills and return ducts are unfortunately very common. They can also be the most difficult and costly problems to correct. However, there some other solutions to this irritating problem that you may want to take a look at first.
The most common air filters used in residential heating and air conditioning systems are pleated filters and they often don’t fit well into the return grill or air handler. Return air, like electricity and water, takes the path of least resistance and the path of least resistance is often around the air filter instead of through it.
Unfortunately when air passes through these narrow spaces between the filter and the filter housing, it can cause whistling or even hissing noises that quickly become very annoying.
Before You Call A Contractor
Here are 5 Easy Solutions to Whistling and Hissing Noises that Don’t Require a Contractor:
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Ensure your air filter is the proper size for the application. This often means you have to buy custom sized filters instead of the common sizes supplied at hardware stores but the better the fit, the less likely it is that air will pass around the filter.
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In the return grill or the filter rack, which is often difficult to
reach, you can install foam tape (gasket material) around the section where the filter sits. This helps to create a tighter fit.
However, an easier alternative may be to add tape to each new air filter you install. Foam tape is available in 25 foot long rolls and two thicknesses, the thinner option is 1/4 in. thick x 3/4 in. wide. The thicker option is 1/2 in. thick x 3/4 in. wide and is best for filters that fit very loosely.
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Use less efficient filters. Pleated filters have MERV Ratings and the higher the number is the greater the resistance to air flow. Unfortunately, filters with lower MERV ratings won’t clean the air as well as filters with higher ratings.
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Change your filter more often. If you only begin hearing air noises after the filter has been installed for some time, you may not be changing your filter often enough. As dirt builds up on the filter air flow resistance increases and this can result in air going around the filter instead of through it.
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Often when return grills are mounted in the ceiling and the filter is loose it gets sucked up against the duct opening causing a thud every time the fan starts.
This can be corrected by building up the inner surface that the filter hits against so that the filter fits firmly into place and there is no space between the filter and the duct opening for the filter to move (as listed in number 2 above).
A better solution is to install a return air filter which is designed specifically to be installed in return air grills.
This is certainly not every potential problem that may cause your filters to be noisy but these tips will help you to solve some of the most common problems you may encounter.
Best,
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{ 4 comments… read them below or add one }
Bless you ! I hope we find a solution: I”m off my mind with the noise! Are there filters which are made for a most quiet situation ? Doris P.S. in So. FLORIDA big time use , of course . the bit of winter we had was a blessing a.c.noise wise.
I am not aware of any filters designed specifically for that kind of problem. I know it can be a difficult problem to solve but there is almost always a solution.
Hi Don, I just had the HVAC guy clean my furnace and replace the filter today… and only now does the return vent sound loud a definite humming… it’s was quiet up until this point. Was my filter that dirty before… and now it’s free and clear to be noisy again? Any input you have, I’d greatly appreciate. I don’t wanna be that guy that calls back the serviceman with a panic about nothing.Thanx
Karson
Hi Karson,
It sounds like air is being drawn in around the filter. This sometimes causes the filter to vibrate and results in a fluttering or humming sound.
Often these sounds can be eliminated by adjusting the way the filter sits in the filter rack or return grill. Try adjusting the way the filter is sitting first to see if the noise stops. There is usually room to make a small adjustment.
There are a couple of other possible causes but they are more complicated to solve and if the problem is new it’s not likely the cause of your problem. If you would like more information check out the youtube videos below.
http://youtu.be/qUhf6fIeC0I
http://youtu.be/68ZCA9kv0qM