loud air return...causes/fix it ?

trailrunnerbikerDecember 24, 2010

We had one large air return in the stairwell of our home. When we had a new Trane system installed the company told us we needed to add another smaller 2nd air return to increase the efficiency of the unit.

The discussion of placement was a problem and I finally let them place it in the wall of our bedroom. I explicitly explained that I was sensitive to noise. I was assured that it would be OK.

Of course it isn't OK. It is so loud that I can't sleep when the HVAC comes on. In summer we simply shut the unit off and have a ceiling fan and that is enough. In the winter though our old 1890 11 ft ceiling home gets too cold. The TM is so great that we can't let the house get that cold.

What are the reasons for an air return to be so loud ? Is there a solution , short of having the whole thing moved which would be a mess and expensive ? I have tried the test of opening the cover to see if it is due to a restriction in that area but it is just as noisy . Could it be that the duct is smaller at that point and that the noise is due to restricted air flow ? Any solutions would be much appreciated. I have been in homes where you couldn't tell the HVAC was on the returns were so quiet. c

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How long has it been since you replaced the air filter and what type is it. One other thing you can try is pull the filter and with the unit running check to see if the noise level gets better or worse and report back. Is the ductwork metal or flex duct is good to know also.

    Bookmark   December 24, 2010 at 2:32PM
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We change the filters at least monthly...they are a Filtrete and are $20 for 2...I hate paying so much and I know they have a higher resistance but they get really dirty...gas heat and the dust of an old house so we have stuck with them...let me know if I should use something else.

When I have the unit running and take out the filter it is almost silent...sigh....can't leave it like that ...can I ???? haha. We have hard metal duct...I thought you always had to have hard duct with hvac systems....THANK YOU for any tips...c

    Bookmark   December 24, 2010 at 8:37PM
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Is the new system larger than the previous one? It sounds like the system was made larger and the contractor tried to compensate by adding another return. The fact that is noisy suggests your duct work cannot handle the increase in airflow.

Is it possible for the contractor to reduce the airflow? There may not be much of any adjustment, but it is worth a try.

It is interesting the noise is eliminated when the filter is removed. Filtrete filters are very restrictive. I suggest trying a pleated filter with a rating no higher than Merv 8. Is there room for your contractor to modify the furnance return to allow a 4 inch filter? The 4 inch filter is less restrictive than the 1 inch and you won't need to change it monthly.

    Bookmark   December 24, 2010 at 10:20PM
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Yeah I second that either you need to try something in the merv 8 range or better yet have your system adapted to hold a 4" filter. What size is your system in tons and what dimensional size is your filter. You might have the ability to bend some tabs and insert a 4" filter depending on how your filter goes in. I had the ability to bend some tabs and with the 4" filter everything is so much better. I think your best bet is get a 4" filter and if you need someone to come out to adapt for the thicker filter you might as well see how much more it would be to go a size bigger while your at it.

    Bookmark   December 25, 2010 at 12:16AM
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Third - it is your filter. Buy the $.50 ones - they are much quieter. My returns were loud with the Filtretes and I have huge returns (system was downsized from 4 to 3 and they added a return to help balance it so I have 4 returns with a 3 ton system). Even with "enough" grill space, the Filtrete was loud. Even the $3 pleated filters were loud.

There is nothing dusty about gas heat so I'll blame your old house. Just as a comparison, I change the cheapy ones every 3 months and it is hard to tell they are used. There are lots of factors there including probably climate.

    Bookmark   December 25, 2010 at 6:34AM
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When you say the return is loud do you mean the sound of the air being drawn is loud or the actual ductwork(banging of metal sound) is loud?

    Bookmark   December 25, 2010 at 7:50AM
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Thanks for all the responses. We have all new duct work when the system was changed out , everything was gutted as the original job was so bad. I have never seen a 4" filter. I don't think anything like that would fit as the 1" sits right against the metal framework inside the return.

I have seen the reusable ones and wondered if anyone has those...you evidently clean them and replace. As far as loud it is the air noise...no banging LOL.

David the problem with the cheap filters and the fact that yes they last and last and don't look dirty is that indeed they let everything through :). I have tried them at our last house and stopped as they never looked dirty and the " expensive good ones" did...so there you have it. The reason they don't get dirty is they don't catch the dirt...at least in my house.

We have gas fireplaces and we burn candles and we have a gas cooktop...with all of that my husband says that is the black that I see on the filters...he says that gas is dirty.

I am amzed that a 3ton system has 4 returns. I would go crazy with that many returns. I hate the sound of the air movement and I hate the current of air it creates in the stair well etc. I am glad I only have to contend with these 2 downstairs. We have a heat pump upstairs that is a whole separate system and one return up there. It is also a 20x30 return and since that 1300 sq ft space is " open" they only put the one return. It is quieter than the ones downstairs.

I don't know how many tons the unit is....there are the 2 returns...20 x30 in the main staircase at the foot of the stairs and the 20x16 in the wall of our master suite right inside the door. He walked around and looked and looked trying to find a good place for the 2nd one. This was not his 1st choice...he wanted to put it in the foyer wall area of our master suite and I wouldn't let him....I had plans for decorating the area with an old chest and I didn't want to have to have that ugly return taking up the wall. He would have made it another 20x30 and it would probably been way better....and quieter etc...I was pig headed and had design issues LOL. So I guess this is ALL my fault.

I will look into the 4 " filter and wait to see what you guys have to say. Here are a couple pics...

he wanted to put a 20x30 where this chest is sitting: ( this is off the kitchen)

instead it is around to the left inside the room on what would be the same wall.

Thanks for all the help !! c

    Bookmark   December 25, 2010 at 11:01AM
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Right - the cheap filters only catch big stuff. And arguably, that is all you need to catch. The filtrete 1 inch catch stuff but that "stuff" wasn't hurting anything (arguably).

If you want to get dust or allergens out of the air of your house, the 1 inch filtrete is not the answer - particularly if you are sensitive to noise. I don't personally think the 4inch filters in the 1 inch spot are the answer either.

A seperate media filter cabinet way away from your ears with a 4 inch filter would help with the dust. That is your answer - works far better anyway.

Candles maybe burn with particulates. A gas range does not have any significant particulates. A gas fireplace - well I suppose that depends on design. Modern direct vents - absolutely not. Exposed gas logs that get dusty might burn with particulates but usually a chimney takes care of that pretty well.

BTW - the filtretes in my house with gas range and gas fireplace did not ever pick up much of anything. But again - 4 returns (actually 6 total). More returns = less noise - but I know you realize that.

    Bookmark   December 25, 2010 at 11:26AM
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I would stay away from the glass fiber filters and go to a low merv (8 or less) pleated. I had room for the 4" filter and the media area is over 10' long which still allows good filtering and air flow.

    Bookmark   December 25, 2010 at 12:14PM
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Can you post a picture where of your filter set up? Perhaps your duct work can be modifed to install a box to accept a 4 inch filter. What size filter are you currently using? It may be too small in area for the amount of air your furnace and AC are trying to move through it.

    Bookmark   December 25, 2010 at 1:28PM
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One of the reasons to run a decent filter is to clean the air for us but also to clean the air to keep the coil and blower from collecting gunk and reducing efficiency.

    Bookmark   December 26, 2010 at 3:24PM
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The filters are really there to protect the HVAC equipment, not filter the air in your house. The inexpensive, fiberglass filters will do that job just fine and will also solve your noise problem. If you must use the pleated filters, use them on the return that doesn't make so much noise.

    Bookmark   December 26, 2010 at 9:48PM
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We had to go out of town so no pics yet. I will do it later next week when we get back. We are using pleated filters now that are so expensive although they are not the most expensive . They are at Lowes and are 2/$20. I hate paying that much but thought it was to clean MY air not the air for the mechanics...although it makes sense that it does it for both but more for the mechanics.

Since I am seeing the "black/charcoal" color show up on the filters so soon after replacement I am wondering if I should have the duct work cleaned/whole system. It is only a couple years old though and I had them come and clean the squirrel cage etc 1 1/2 yrs ago. He said it was dirty. But we have not had the duct work cleaned...I always read conflicting reports as to whether to do it or not. We have a certified person that advertises in the area and has been in business in HVAC for many years. Opinion on that?

As to the noise I gave up the other night and we moved to another bedroom...complete silence...ahhh...so pleasant. You can't hear even the air flow in the floor vents, it was wonderful. So that is an option for now is move out. I will get pics and look at the other filters and also would appreciate a link to any other kinds of return covers...I tried a Google search and didn't see anything that said it was open and less restrictive to air flow.

Thank you for all the suggestions...I am going to keep on this. c

    Bookmark   December 30, 2010 at 9:21AM
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I am curious why your filters are so much dirt so quickly. You can investigate a duct cleaning service, but in the past I have read these services don't do much in terms of cleaning.

Was the duct system a retrofit in your 1890 house? Is it possible part of the duct is system is using wall cavities to move air around the house? This may explain why you are picking up so much dirt.

Try an expensive $4 pleated filter from Lowe's before you start spending money on duct cleaning. It may help reduce the noise. You may have to change these monthly.

    Bookmark   December 30, 2010 at 11:01AM
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I wish I knew why the filters get so dirty looking so fast also. I know the air in general in our town is dirty. Asphalt plant not far away and when you have furniture outside you can wipe it down and see the same black soot like stuff on it so my husband says it is dirty air in general.

As to the duct work. It is all new when the Trane system was placed and it is all in the crawl space and it is all very much intact. We checked to make sure there were no breaches in the covering of the insulation on the duct etc. But no there isn't one drop of it in the walls. It comes straight up into each floor vent.

Do you mean " inexpensive $4" filter. I will do so when we go home. Thanks. c

    Bookmark   December 30, 2010 at 4:41PM
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Ah, I suspect the source of your dirty air is a leaky 1890 house combined with an asphalt plant right down the road. Is your house drafty, or are there parts of the house that you know are drafty? Your new HVAC system has plenty of suction and it's probably pulling air in from all of the leaks around your walls, ceilings, windows, etc., which is also pulling in particles from inside the walls and ultimately from the outside.

Check with your local utility company and ask about energy audits that include a blower door test. That test will help you pinpoint the sources of air leaks so that you can address them. Or, you could tackle a DIY energy audit and use an incense stick or match to test for leaks. The Energy Star website has a PDF doc that walks you through the steps of a DIY air leak testing & sealing process.

    Bookmark   December 31, 2010 at 9:12AM
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tm: I am sure you are right. It is what DH has said since we moved in yrs ago. Leaky old house + dirty air = dust/soot/drafts.

As far as plugging leaks we probably need to do a better job. We had all the old nasty insulation under the floors, in the crawl space, torn out and we had new put in. Dh says there are still places that are missing some...you can tell when you walk on the floors when you walk on a colder spot. He said also that some of the wires that hold it in place are sagging so he is going to get in there w/ some batts and and wires and fix that. We added storm windows a couple years ago so the windows are very good and there are no drafts there. We used a candle to see the worst places. Part of the problem is the old chimney which has 2 gas inserts back to back. I know that when we use the 1400 cfm hood in the kitchen, we use it on low or medium, that it draws and is probably pulling soot into the house via that route. We have 2 other gas inserts also but they have a new stainless steel chase so less likely to be a problem but still...one wonders.

We had not thought about them coming to do an audit of that kind but that is certainly a possibility. Do you have any idea what that runs, cost wise? If we could save more on heating and get cleaner air it would be worth it. Thank you c

    Bookmark   December 31, 2010 at 11:36AM
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Yes, I meant inexpensive $4 filters. It sounds like you need to be changing the filters monthly. The cheaper filers are a good option.

    Bookmark   December 31, 2010 at 12:03PM
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The cost varies from area to area. I would say $300 or so might be a ball park number, but it could be less if subsidized by the local utility company.

    Bookmark   January 1, 2011 at 9:23AM
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    Bookmark   June 5, 2011 at 8:29PM
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