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Old 11-03-2011, 06:44 PM   #1
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Grill direction

Does it matter what direction a return air grill faces? our furnace is in the basement and all the return air grills when we bought the house had the open end facing towards the ceiling (they are all on the lowest part of the floor) if the duct is going down, and the louvers point down does that impact the air flow? should they pull the air in one direction instead of making the air do a U shape to go from the floor up then pulled back down into the duct? or does it not matter at all? I've noticed since the last HVAC guy was here and flipped all them around we have a lot more humming in the duct system....


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Old 11-03-2011, 07:26 PM   #2
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its more for looks then the air moving thru them having them pointing down at a low point on th wall blocks the view into the duct...unit will not be effected you usually don't want any noise thru them...


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Old 11-03-2011, 08:19 PM   #3
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Check to make sure the grills are screwed in tight. You can push on the louvers to see which one is humming.

But I have a question that may or may not relate to this,
Do you have hearing aids? I ask because I used to take care of a retirement community. It seemed that those that had hearing aids had the most complaints with system noises.
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Old 11-04-2011, 01:10 AM   #4
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Humming is the result of the grille blades vibrating as the air is pulled through them.It doesn't make much differance which way they are facing so if turning them around stops the humming then do that.
The only other way to stop the humming is to increase the size of the return grilles or the return ducts ,probably both.
If you do a tempature rise check and the temp is too high you can be sure you need better duct or more grilles.At that pouint I would question if you have enough comfort getting into the house as if they cheaped out on the return,they probably cheaped out on the supply too.
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Old 11-04-2011, 05:14 PM   #5
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If turning them back the way they were doesn't sort out the harmonic vibration then you can often reduce or eliminate most of the noice by altering the direction of every 2nd grill fin by 10 degrees with needle nose plyers.
A thin bungee line that is attached from deeper inside of the duct to hook onto the back of the center of the grill will considerably dampen the grills vibrations. But...

Replacing it with a coarse wooden return air grill is the surest bet for eliminating that type of noice.
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Old 11-04-2011, 08:10 PM   #6
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Have you changed your filter recently. Usually the noise is a lack of return air as said. Most of the time a wooden grille will block the return even more.
Would it be possible to add more return airs if needed?
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Old 11-04-2011, 08:18 PM   #7
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The cheap stamped return grills are notorious for vibration.
The alternative is a louvered return grill.

Here is a recommended example


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