Noisy return air grills


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Old 11-09-07, 05:02 PM
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Noisy return air grills

Can anyone direct me to a source for better quality return air grills? My new home has a poorly designed forced air system where every return grill will oscillate causing a howling sound. The reason I claim the system is poorly designed is because the return ducts seem to be undersized. Totally removing the grills will stop the oscillation. If I could find better quality grills that are made of stronger/thicker metal, the oscillation may stop. I am also open to other ideas. For what it’s worth, I have already changed the fan speed to the lowest setting and tried grills with 3/8 inch (instead of 1/4 inch) openings without luck.
 
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Old 11-10-07, 04:59 PM
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You may be lack of returns! Returns should not be making that much noise. How many returns do you have in the home, and what sizes are they? How many BTU is the furnace, and tonnage of the A/C?

You said you drop the heating speed down... You better check the temp rise, otherwise you are going over heat the heat xchanger and shorten the life of your furnace.
 
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Old 11-10-07, 08:51 PM
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Im with Jay sounds like you have a duct issue not a grile.
 
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Old 11-11-07, 05:16 PM
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Thanks for the comments and I totally agree the return air system is undersized. However, removing the return air grills will provide quiet operation. Regardless if the system is improperly sized, I am very interested in finding high quality grills that are more substantial in construction. The grills I currently have are flimsy! If you run your fingernail across the louvers, they will resonate like a tuning fork!

By the way, good comment on the fan speed. I will ensure it is set back to the original setting.
 
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Old 11-11-07, 06:18 PM
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You could get better grills, but if you are lack of numbers of returns or wrong size, it's going to kill your system.

so, how many returns do you have? What sizes are they, and how many BTU is your furnace and A/C?
 
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Old 11-12-07, 11:33 AM
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Wink

First you might try and bend each small bar in the grills just a little over what they are now. This helps cut down on the grills that resonates. Also go to below. You will find a better grill for there

http://www.valueac.com/aircosu.html?...56877521grills and registers.
 
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Old 11-12-07, 05:55 PM
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Jay,
I have 4 returns - two are 32 x 10 inches and the remaining two are 16 x 10 inches. I don’t know the BTU, but the model number of my Payne Gas Furnace is PG9MAB036060AASA (I assume this will provide the BTU rating). I have no AC.

It seems to me that the return air flow seems modest as measured by placing my hand inside the wall opening during system operation. It puzzles me that seemingly slow air flow will cause my grills to resonate.

-------------------------

Ed,
I have tried to bend the louvers without luck. If I am unable to locate some robust grills, I may solder a reinforcement bar across the louvers or have some stout grills specially made. Still, it seems to me that in the world of HVAC, there should be a simple resolve. Also, thanks for the link to the grill manufacturer!
 
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Old 11-12-07, 07:26 PM
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Sounds like you got the right amount.

Are the grills on the wall near the ceiling or near/on the floor?
 
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Old 11-13-07, 05:20 PM
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Jay,
The return grills are all located on the wall about 10 inches up from the floor. It just seems odd that the low airflow into the return openings provides the undesired noise. I have tried other grills with 3/8 inch openings instead of the current 1/4 inch openings. The 3/8 inch versions also "howled" (at a lower frequency).

I really appreciate everyone's time and input!
 
 

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