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  1. #66
    Join Date
    Jan 2019
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    Crystal Lake
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    Thread Starter
    Quote Originally Posted by TechmanTerry View Post
    Try reading a little bit of proper zoning info. Something like the ACCA Manual Zr, residential zoning. Or, Forced Air Zoning,by Robert C. Ring from CONTRACTING BUSINESS Magazine,August 1995. Or Carrier Training 33ZC ComfortID or Carrier COMFORT ZONE 11-B or Carrier Advanced Training# GTA3-101 "Air,Air Problems & Measurements. Knowing what is required might help your thinking.
    Will look that up, thank you

    Quote Originally Posted by TechmanTerry View Post
    How many units are you displaying in those photos?
    One unit. One furnace

  2. #67
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
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    Just a Q here. That supply plenum measurements seem's to match the OD dimensions of the AHU. I believe that the supply plenum "starting point" is supposed to match the opening measurement of the blower outlet opening of the AHU,yes,no? ++++++ I just realized that is a cased coil, woops.

    Then I also thought that the AHU takeoff supply duct had to be a certain length, in order to allow the un-even/un-balanced air that exits the blower housing to get organized/mixed evenly, properly.

  3. #68
    Join Date
    Jan 2019
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    Crystal Lake
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    Thread Starter
    Quote Originally Posted by TechmanTerry View Post
    Just a Q here. That supply plenum measurements seem's to match the OD dimensions of the AHU. I believe that the supply plenum "starting point" is supposed to match the opening measurement of the blower outlet opening of the AHU,yes,no? ++++++ I just realized that is a cased coil, woops.

    Then I also thought that the AHU takeoff supply duct had to be a certain length, in order to allow the un-even/un-balanced air that exits the blower housing to get organized/mixed evenly, properly.
    Yes, that is case coil. We have made few changes recently. add flex connector right after the coil and change plenum a little bit. just to make sure is not vibration transferring through duct work. There is no more space to get longer plenum. But like I previously sad while installing canvas connectors on supply and return main trunk. I had whole plenum removed. just coil on supply side and filter housing on return side. we are talking wide open return and supply. start furnace and went upstairs to listen. same noise present. with no duct work attach to it at all. that makes me think that is furnace or coil making noise.

  4. #69
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
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    Quote Originally Posted by adamf79 View Post
    Yes, that is case coil. We have made few changes recently. add flex connector right after the coil and change plenum a little bit. just to make sure is not vibration transferring through duct work. There is no more space to get longer plenum. But like I previously sad while installing canvas connectors on supply and return main trunk. I had whole plenum removed. just coil on supply side and filter housing on return side. we are talking wide open return and supply. start furnace and went upstairs to listen. same noise present. with no duct work attach to it at all. that makes me think that is furnace or coil making noise.
    I think what you’re hearing is a VS or X13 ECM motor. They can make some funny noises.

    Could be a blower wheel out of balance

    Could be a piece of plastic on the underside of the coil.

  5. #70
    Join Date
    Apr 2012
    Location
    Millsboro, DE
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    181
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    The static is too high, the motor may self-destruct.

    I'm not permitted to give you specifics here, but in general terms:
    1. Tear this out and put in a horizontal arrangement.
    2. Nobody said there could only be one media air cleaner, keep the velocity below 350 FPM if you can. A lot of manufacturers require returns on both sides.
    3. Use low resistance elbows (inside radius = 0 unnecessarily adds to duct length) and fittings ("deadhead" can be 120 feet of duct); see Manual D Appendix 3 - lot of good stuff there.

    AND do check your cooling load calcs before you do anything to verify five tons is required.

    The one duct job is beautiful!!!

  6. #71
    Join Date
    Aug 2009
    Location
    Beatrice, NE
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    This just hit me but it doesn't explain why it is an issue now and not before. I forget but that was either 4 or 5 ton. Most manufacturers require more than just side return on 4&5 ton systems. You may want to try running it with the blower door off to see if it makes a difference.

  7. #72
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
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    Quote Originally Posted by BNME8EZ View Post
    This just hit me but it doesn't explain why it is an issue now and not before. I forget but that was either 4 or 5 ton. Most manufacturers require more than just side return on 4&5 ton systems. You may want to try running it with the blower door off to see if it makes a difference.
    He is using side and bottom which is fine. I don’t think we have a duct issue here. The ductwork looks better than 99% of duct jobs

    Quote Originally Posted by adamf79 View Post
    Carrier Media filter 24x25x4.
    Furnace is getting a return from the bottom and the side.
    We have a pretty large return on the furnace, return is not zoned. a furnace is getting about 2100CFM back when running at 2nd stage.





    Yes gas furnace and AC,

    Yes, noise is NOT coming through registers. Noise is coming through the floor above the furnace.

    We did not get canvas installed as old duct work that was way undersized did not have that problem. I was actually going
    to cut in and install some canvas on both supplay and return main runs.

    Some vigration is present, seems to be normal.

    Noise is present with heat, AC or just fan at higher speed (satge 1 or 2)

    Measurement for total static was taken before the blower and between furnace and case coil.




    We utilize all the room so there is no more room above the furnace. I can change the design if that would help or posibly insulate duct inside on the top so when air hits it will get muffle a little.

    I'm also attaching pictures. one of the pictures shows old ductwork that was extremely undersize, before zoning was installed.

    Attachment 806087Attachment 806088Attachment 806089Attachment 806090Attachment 806091Attachment 806092Attachment 806093Attachment 806094Attachment 806095Attachment 806096

  8. #73
    Join Date
    Apr 2012
    Location
    Millsboro, DE
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    You might also check the manufacturer's performance charts for how much dehumidification occurs at 500+ CFM/ton on that system, if it is 4 tons.

    And do check Appendix 3 for the EL's ("Equivalent Lengths" in feet of straight duct) of the fittings used before completing your analysis: As stated your upper limit is usually 300 to 400 feet TEL ("Total Effective Length" - I called it "length of duct"); something that looks good is often bad.

    And yes, a bottom return is usually accepted by manufacturers in lieu of two side returns.
    Last edited by ferd1942; 02-21-2019 at 08:56 PM. Reason: added "/ton" and comment on bottom return

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