Noisy Return Vent

[bofa]

This is something that has driven me nuts for a while... the main air return vent has a loud resonating hum at times. I had the AC checked recently and everything is fine. The guy told me to try bending the vents a bit and see if that works... that a professional fix would probably involve adding more duct work, making the return box bigger, and/or adding more returns - all of which are pricey and I'm trying to avoid putting too much more into this place.

Based on our discussion and the system's performance, I don't think its a balance or flow problem. If I put a little pressure in certain spots (specifically the long flat pieces) the resonating goes away. So I'm thinking I need to either modify this thing to stop it from resonating or to see if I can get some kind of plastic return vent.

Any suggestions or experience here?

 

[bofa]

:bump2:

Anyone? I can't seem to find plastic vents in this size. I took it down and lined with foam insulation tape yesterday and that has done nothing.

 

[bofa]

I ordered a new "industrial" grade vent cover. Hopefully the steel will resonate less than the current aluminum one.

 

[KCcarguy]

I've noticed this too. I just decided to turn up the stereo a little.

 

[bofa]

I've noticed this too. I just decided to turn up the stereo a little.

Hah, I've tried that. It's just more annoying when I'm trying to go to sleep. I think bending the vents made it worse actually because now I'm getting two different tones in perfect dissonance. I wanted to stab my eardrums last night. :lalala:

 

[1engineer]

It's a velocity issue and any real fix would entail what your contractor told you. Bigger = less velocity in this case. Only band aid fix in this case is to straighten out as much as you can any bends. If that does not work then try taping some type of foam to the vibrating sections. If that does not work then....spend some money lol.

 

[bofa]

It's a velocity issue and any real fix would entail what your contractor told you. Bigger = less velocity in this case. Only band aid fix in this case is to straighten out as much as you can any bends. If that does not work then try taping some type of foam to the vibrating sections. If that does not work then....spend some money lol.

Well, I think the blower was overpowered from the beginning. I found a setting to reduce the blower speed by 15%. It seems to have helped a little and I'm noticing less humidity as well and no loss of cooling. Now the vents dont feel like they are going to blow you over when you walk by. Hopefully the new return grill will help a little but my expectations are low.

I should also add that this was the second return grill for the unit. The original one didn't have this issue but the slats got a little loose and squeaked occasionally so I thought I was being proactive in replacing it. The new one made noise but its gotten worse over time.

I wonder if that foam spray (great stuff?) along the flat sections would help. Foam insulation tape did nothing.

 

[1engineer]

Well, I think the blower was overpowered from the beginning. I found a setting to reduce the blower speed by 15%. It seems to have helped a little and I'm noticing less humidity as well and no loss of cooling. Now the vents dont feel like they are going to blow you over when you walk by. Hopefully the new return grill will help a little but my expectations are low.

I should also add that this was the second return grill for the unit. The original one didn't have this issue but the slats got a little loose and squeaked occasionally so I thought I was being proactive in replacing it. The new one made noise but its gotten worse over time.

I wonder if that foam spray (great stuff?) along the flat sections would help. Foam insulation tape did nothing.

No such thing as a blower being overpowered, just the rest of the system is undersized lol. Try the Great Stuff if it will never be seen. Couldn't hurt! Then you could make a volcano out of what you have left...

 

[bofa]

No such thing as a blower being overpowered, just the rest of the system is undersized lol. Try the Great Stuff if it will never be seen. Couldn't hurt! Then you could make a volcano out of what you have left...

That's true. The original system from construction died about 6 years in and we had to get a new complete unit, which was more powerful, more efficient, and used better cooling materials. But of course the vents and duct work were left over form the original install. I think detuning the blower was the cheaper and more immediate option. If I was going to be here a while I'd look into getting all that done but we're outta here in 3 weeks! :reddance: