New Install, Noise concern
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  1. #1

    New Install, Noise concern

    I am looking to replace a 2 ton condenser and air handler, with a condensing furnace, coil and outside condenser, inside equipment moved a bit from 1st floor closet to a kneewall attic above. Tieing into existing ist floor ductwork in crawlspace below (equipment itself cannot be located below 1st floor by code)

    I have 2 proposals and waiting on a third (for a month despite my followups) but none of them address my noise concern with any specifics. I know what many will say, but believe me getting a proposal is like pulling teeth in my area, let alone one with any specifics or, God help me, an actual load calculation....... The new location will be virtually on top of the Return Air intake..... maybe a foot of vertical duct and a 90 degree turn, filter, then into unit with blower right there at return opening. Because of some of my reading here, I mentioned my concerns but didn't get any specific answers, I'd like to agree on some minimum standards in the contract that can help, like duct lining. Still such a short run concerns me. Is there anything else I can do? I don't see how return can be lengthened as often mentioned due to location unless they installed the furnace vertically using a kind of reverse of the typical return drop (Meaning upward, entering top of downflow furnace) instead of the seemingly more natural horizontal position spanning the return and supply duct.

    Are there 2 or 3 things I can specify that typically can help with return air noise from such a close blower motor? (Return air opening will be adequate size so the speed of air through grill won't be the offending issue)

    Could it make sense to actually orient the install like I mentioned. I'm sure they will have their own thoughts on that but I want to be as specific as I can to alleviate the noise issue not realize an unacceptable problem until startup

  2. #2
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,057
    Quote Originally Posted by sandcastles View Post
    I am looking to replace a 2 ton condenser and air handler, with a condensing furnace, coil and outside condenser, inside equipment moved a bit from 1st floor closet to a kneewall attic above. Tieing into existing ist floor ductwork in crawlspace below (equipment itself cannot be located below 1st floor by code)

    I have 2 proposals and waiting on a third (for a month despite my followups) but none of them address my noise concern with any specifics. I know what many will say, but believe me getting a proposal is like pulling teeth in my area, let alone one with any specifics or, God help me, an actual load calculation....... The new location will be virtually on top of the Return Air intake..... maybe a foot of vertical duct and a 90 degree turn, filter, then into unit with blower right there at return opening. Because of some of my reading here, I mentioned my concerns but didn't get any specific answers, I'd like to agree on some minimum standards in the contract that can help, like duct lining. Still such a short run concerns me. Is there anything else I can do? I don't see how return can be lengthened as often mentioned due to location unless they installed the furnace vertically using a kind of reverse of the typical return drop (Meaning upward, entering top of downflow furnace) instead of the seemingly more natural horizontal position spanning the return and supply duct.

    Are there 2 or 3 things I can specify that typically can help with return air noise from such a close blower motor? (Return air opening will be adequate size so the speed of air through grill won't be the offending issue)

    Could it make sense to actually orient the install like I mentioned. I'm sure they will have their own thoughts on that but I want to be as specific as I can to alleviate the noise issue not realize an unacceptable problem until startup
    Post your location, and then check the dealer locator in the index on this site.A little more detail or pictures would help. What code are you referencing about location of equipment?

  3. #3
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,207
    Never heard of a code like that, must be one of those California things

  4. #4
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,207
    You will get better efficiency if unit is in conditioned space so I would keep it in the closet. Duct liner on plenums and properly sized flex duct with at least 2 90 degree tuns in return duct will usually deaden any blower sound transmission

  5. #5
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,057
    Possibly a flood zone area

  6. #6
    Quote Originally Posted by second opinion View Post
    Possibly a flood zone area
    Pretty much...Coastal, basically the same.
    closet holding aH was deemed too shallow at 24" for furnace

    Attic can easily be enveloped/insulated and kept as partially conditioned if warranted, It sort of is now.

    I hear you on the flex with two turns but that seems like it will end upp looking like a pretzel with turns just for the sake of turns Wooried that might induce other (static ) issues?

    I guess the point is I need to get at least some separation between return and the unit, with some kind of turn, 1 being better than none?

    which is better? metal duct with lining or flex?

  7. #7
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,207
    As long as it is sized correctly and installed without kinking or cramming it won't affect the static pressure. If the knee wall attic area is hot then the longer the length the more heat it will pick up but we install equipment in attics a lot and as long as the duct is sealed and insulated well (r8) you shouldn't have a problem. IMO flex deadens sound better than lined metal but you do have the potential of the cable guy stomping all over the flex and ruining it but they tend to ruin metal duct just as bad. 180 degrees of turn deadens a lot better than 90 degrees of turns but sometimes it's just not possible. Turning vanes or baffles in plenums will help to deaden noise as well

  8. #8
    Thanks for the thoughts, It at least gives me some confidence to brings up points of concern and not settle until clear resolution is formulated and agreed to.

    "Attic" area kind of paints a bit of an incorrect picture versus what it really is. It's more an alcove under a sort of Dutch roofline on the 2nd floor. Actual attic is above 2nd floor. This area, for instance, is a closet in another similar area, and with some minor framing could easily be converted to a closet here. The steep roofline also faces North and gets little sun. Not really much of an issue as far as summer heat goes. Actually more of an issue of winter cold, condensate line freezing etc although our winters aren't so severe that that isn't easily dealt with... insulating it like the closet is easy enough if warranted.

    I did check the pro locater but no one within 70 miles of me.

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