[mrjonm]

I have a small 850sqft condo. Lived her a couple of years. I have an old Borg Warner 65000 input BTU/HR unit. Model P3UGD080N6501A. Its an older unit. There is only one return in the condo which is located on the far side of the living room, connecting directly to the HVAC unit which is on the other side of the wall in the HVAC utility room. When the system kicks on, its so loud that I have to turn up the television, then turn it back down when the unit shuts off. The AC and Heat is working fine. Its not a defective noise, or a humming noise, its just a very loud wind noise as if it has a very powerful fan. Its always been this loud. The round turbo fan is located in the unit right on the other side of the wall of the return vent. I can see it right there when changing the filter. Is there any way to quiet or buffer this noise? Any suggestions would be highly appreciated.

[esquire1]

Put up sound retarded insulation on the inside wall. That will help a bunch

[mrjonm]

The noise is coming straight from the return vent through the filter, since the fan is right on the other side of the filter.

[labman]

Have you turned it on with the vent and filter removed? It is possible the vent and filter is undersized for unit. My furnace has 2 filters almost as big as the hole into the furnace arranged in a VEE shape. Can you enlarge the vent, or add another one on a different side?

You could also look at slowing the fan. Many fans have several speeds selected by connecting different windings to the relay that powers the motor. Too slow, and you could cause the coil to ice up.

[mrjonm]

The filter hole size is 20" by 14". I have tried it with the filter out, same results. No "V" shape. The unit is right up against the wall on the other side of the filter. Basically, you open the grid, remove the filter, and the fan is 8" in. I'm not sure I want to try to change the fan speed. Wouldn't that make the unit run longer to cool or to heat?

[labman]

Many units are already set up to run slower in heating mode. In A/C mode, less, but cooler air would come out. Might or might not make much difference. Is the unit as noisy in heating mode?

[mrjonm]

Yes, it's just as loud with heating. It's the fan. Not a defective sound. Just wind sound. Wonder maybe since this is a very old unit, I could get a newer quieter fan?

[labman]

I think I have seen stuff on the angle of the fan blades. Some angles are more efficient, but noisier. Finding a better one that fits your furnace maybe tough. Not sure where to even suggest starting.

[ronny]

Had the same problem. Solved it today. My setup is different than yours so don't know if this will work for you. This was fairly easy and worked wonders.

My CA unit sits about 20" off the floor and takes return air in from an empty area below it. My return and filter are at floor level and at right angles to the bottom of the unit.

I installed a baffle at an angle between the return vent and the fan and covered the bottom side with some old carpet. This forces the air to make a bend after it flows over the carpet, which muffles the sound of the rushing air.

This is hard to explain. Maybe the attached file will help, if I did it right.

If you try something like this, just be sure you don't overly restrict the air flow. I can't help you with that.

[jpadilla]

Had the same problem. Solved it today. My setup is different than yours so don't know if this will work for you. This was fairly easy and worked wonders.

My CA unit sits about 20" off the floor and takes return air in from an empty area below it. My return and filter are at floor level and at right angles to the bottom of the unit.

I installed a baffle at an angle between the return vent and the fan and covered the bottom side with some old carpet. This forces the air to make a bend after it flows over the carpet, which muffles the sound of the rushing air.

This is hard to explain. Maybe the attached file will help, if I did it right.

If you try something like this, just be sure you don't overly restrict the air flow. I can't help you with that.

But wouldn't this effectly reduce the size of the opening to the size of the opening is now the area under the baffle? My loud system is really bugging me but I'm concerned with this solution reducing air flow.

[ronny]

jpadilla, I'm not an A/C specialist, so take what I say with a grain of salt.

I believe if you restrict the air flow too much, it will cause the sound of rushing air, perhaps a whistle, to become very noticeable.

It is possible to determine the area (sq in) of opening necessary for your particular unit. You've just got to be sure you don't restrict beyond this point.

[Donald K]

You can put the sheet metal baffle like the drawing and it will make the unit quieter. Would not recommend putting carpet on it though, carpet collects too much dust and other funky stuff after a very short while and if you have any allergies at all you will be in serious trouble. The sheet metal by itself will normally do the trick---just enough to make the air bend without going straight to the fan will normally do the trick. A rule of thumb for return air is whatever your a/c tonnage is (2 tons 12,000buth, 2 1/2 18,000btuh, (12,000 btuh per ton) take the tonnage ex--2 ton and multiply by 200---2x200=400 square inches of return air filter (20x20 filter--or any equivilent) and your airflow should be good.

[ronny]

You can put the sheet metal baffle like the drawing and it will make the unit quieter. Would not recommend putting carpet on it though, carpet collects too much dust and other funky stuff after a very short while and if you have any allergies at all you will be in serious trouble. The sheet metal by itself will normally do the trick---just enough to make the air bend without going straight to the fan will normally do the trick. A rule of thumb for return air is whatever your a/c tonnage is (2 tons 12,000buth, 2 1/2 18,000btuh, (12,000 btuh per ton) take the tonnage ex--2 ton and multiply by 200---2x200=400 square inches of return air filter (20x20 filter--or any equivilent) and your airflow should be good.

Your point is well taken. I have found that the carpet serves to muffle the sound a little. Since my jerry-rigged unit is behind my filter and I clean my filter regularly as well as vacuum that little piece of carpet, I've had no trouble with it.

Thanks for the formula.

[BILL60]

I live in a townhouse which I rent and it too has a loud noise of rushing air ocming out of the duct in the wall in the living room-the one closest to the furnace and blower which is just behind the wall. I have tried everything to cut donw on the noise to no avail-I vcut a piece of plexiglas to cover the ven and drilled holes in it to cut out the noise and it seems to work but it also cuts down on the maount of heat coming out. I see someone else wrote about baffling the incoming air under the furnace which is mounted about 20 inches off the ground so I am going to try this next. It drives me crazy that I have to keep turning up and down the TV when it is running so I can hear the telelvision but the mgnmnet says some of them are just like that. In other words, they aren't going to do anything. Oh yes-I didi oilt he motor since I figured that never gets doens but it made no difference. Any other suggestions?:) :) :)

[Donald K]

It sounds like what you have is a bad ductwork installation.
When you have a supply run coming off the main supply trunk (especially the first one) there is normally a baffle installed where the supply run comes off the main trunk. IF you have a baffle and can get to it adjust the baffle to decrease the airflow to this one run. IF you don't have a baffle or can't get to it take the plastic top off a coffee can, remove the supply grille (take the srews out) so you can cut the plastic the size of the ductwork feeding the grille----cut a smaller hole in the middle of the coffee can lid -- what you are doing is making your own baffle---try to get it back into the duct 4-6 inches if you can--put your grille back on that could solve the problem.
Good Luck:confused:

[BILL60]

Thanks for the advice but I already used a [iece of plexiglass which I cut to the size of the vent and I drilled holes evenly spaced in it to allow for the air to come out but I didi try putting a piece of rug underneath the intake area before the filter and that seems to help a lot. The main vent from the hot air flow has two roubd vents before it comes out the register closest to the vent in my living room-the loudest one, I had put one of those pieces of filter foam to filter the air. Any other ideas would be helpful. Thanks

[OrlandoCreative]

Your point is well taken. I have found that the carpet serves to muffle the sound a little. Since my jerry-rigged unit is behind my filter and I clean my filter regularly as well as vacuum that little piece of carpet, I've had no trouble with it.

Thanks for the formula.

They make sound dampening products such as this that help with HVAC or vents. I have the same problem with my AC unit (older home with central air added later). I think I will use a baffle and the sound material.

Echo Absorber Natural - echo and noise eliminator

[Testecha]

I have the same return air vent noise problem. Is it true or has anyone heard that significantly lengthening the return air duct greatly reduces the noise at the vent filter?
Thanks for any help provided.

[hvac1000]

Duct properly sized has a way of making the system much more quiet especially on the return side. Many units have little or no actual return ducts and under those conditions the systems are very loud from the blower system itself. There is NO magic cure that works 100%.

[Testecha]

My ducting is the flexible insulated duct. It is about 6 feet from the unit to the return vent grille. Would it get quieter if I added 10 or 15 feet of duct to the existing duct?
Thanks
Test tech a