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  1. #1
    Join Date
    Aug 2006
    Location
    Maryland
    Posts
    137

    Can I add 4 more return ducts to an existing forced air system?

    I recently installed an Aprilaire 5000 EAC and want to know if I can add return ducts to each upstairs bedroom for better air cleaning. I have a 3 level home (basement, 1st and 2nd levels) that was built in 1997 (3400 Sq ft). The unit is a Carrier 2-1/2 ton heating and cooling system (don’t have model # on me). Currently the return duct goes from the basement straight to the upstairs area with 2 large return grills; one in the kitchen area and one in the upstairs foyer. The return duct is about 16x8 or 16x10. I want to branch off the top of the return and install one in each bedroom on the 2nd floor level, so that I am pulling more indoor air to the EAC and possibly get better air circulation. I have access to the top of the return duct in the attic space, so installation should be no problem.

    Can this be done without any adverse effects?
    Are there any limitations to the number of return ducts?
    What’s the best method to do this work?

    Thanks…Al

  2. #2
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    More returns is always better. You can't really have too mcuh return.

    Will it "clean" the air better. NOt significantly. The primary function of a air filter is to keep dust off the coil, blower and heat exchanger. A 2.5 ton system on a 3400sqft home isn't going to turn over a lot of air. Most dust will settle before it can be sucked into the returns. Will it prevent fine dust form being recirculated. Yes. But it's not an air purifier or a clean room HEPA systme with 20-60+ air changes per hour. You would need over over 9000CFM to accomplish that. You systm only has 1000. I'm not saying the EAC is a waste, but don't expect it to purify the air.

    Get a good vacuum cleaner if you want to capture large amounts of dust and if you have bad allergies, get rid of all your carpeting and install hardwood, sheet vinyl or tile flooring and vaccum at least twice a week and keep your windowes closed.


    All that being said, there are other benfits to multiple returns (return in each room). Mainly better system balance when doors are closed, and sometiems an improvement in airlfow to upper floors.

    Do you have a zone system? I would add a zone controls for a 3 story home before I bought a EAC or spent money on returns.

    Careful adding returns in a basement if you have a standard water heater or 80% furnace that uses indoor air for combustion.

  3. #3
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    7,468
    Sure you can, any room with a closable door should have a return for the system to work correctly. Make sure and use a high rvalue insulation on ducts in the attic and keep ducts as short as possible. Seal it all up with duct mastic not duct tape.

  4. #4
    Join Date
    Dec 2002
    Location
    Bellefontain Ohio
    Posts
    220
    This is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary, or ask questions of the OP here.

    You can find the rules for posting and qualifications here.

    Further infractions may result in loss of posting privileges.
    Last edited by beenthere; 05-21-2013 at 07:56 PM. Reason: Non Pro * Member

  5. #5
    Join Date
    Jun 2004
    Location
    Eugene, Oregon
    Posts
    1,018
    Adding more return air drops shouldn't have any adverse affects. I would make sure balancing dampers are install in each return air branch. If not, most of the return air will come from nearest return air drop. I agree with motoguy as to any added benefit gain in indoor air quality. With such a small system in a large house you simply don't have enough air changes per hour to "scrub" the air.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten". --Benjamin Franklin
    "Don't argue with an idiot, they will drag you down to their level and beat you with experience". --Mark Twain
    http://www.campbellmechanical.com

  6. #6
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,006
    I am not going to tell you that your 2.5 ton air conditioner is too small for 3400 ft.² that all depends on how well insulated and energy efficient your home is. That is 1360 ft.² per ton of cooling, I cool my entire first floor with a 6000 BTU half ton window unit, we occasionally have some extremely high and humid temperatures here in Southwest Wisconsin, and it handles it perfectly under all conditions. This is a 1937 farm home with a lot of Windows with storms.

    You're going to have a lot of runtime with that small air-conditioning system; however, and accurate room by room load Calc performed on your home would be helpful, this will be very important when you are going to replace your existing unit.

    I understand that in New York State you can now get free home energy efficiency audits performed, that would be great everywhere; if you could have that done then you would know what cost-effective things you could do to improve the efficiency of your home to a higher level than it is now.

    Here is a free online Whole House Load-calc that you and contractors could use for sizing systems; you need to print & follow all the instructions; when you get it right, print the results as you cannot save them.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,324
    jyost797, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary or ask questions of the OP here.

    You can find the rules for posting and qualifications here.

    Your post has been deleted.
    Further infractions may result in loss of posting privileges.
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  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,324
    Hopefully its a 16X10 return drop. Cause a 16X8 isn't big enough for a 2.5 ton system.

    A return ineach bedroom will help, specially when he doors are closed. you probably won't get a hole lot more return air flow, but it will help some.
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  9. #9
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,969
    From what I just read on the internet, the free energy audits is only for commercial and non profits; no free residential energy audits.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  10. #10
    Join Date
    Aug 2006
    Location
    Maryland
    Posts
    137
    Hello and thanks everyone for taking the time to respond to my post.

    Cold Air Return:
    I measured my return duct last night and it's 20x12. It's good to know that I can add a few to the system. In addition to sending more air to the EAC, I am hoping to get better flow with the additional returns because the master bedroom has vaulted ceilings and does not get as cool/warm as the other rooms; however, I installed ceiling fans in all the rooms to better circulate the air, which has helped tremendously. I would be happy if this method provided some relief.

    Question on Dampers: Air1, as far as dampers, I assume you are referring to the return air duct that will be added to the system. Correct me if I am wrong.

    System Tonnage:
    I will need to recheck the tonnage size because I could be wrong as I was going off of 16 year memory when the house was built. Where can I find that information on the unit?

    Zones:

    As far as zones, the builder did not do any of that and I wish they did or at least offered it as an option because I know the benefits of them. It seems these newer megamansion are being built with better systems these days. I can say one thing though, from years of living in the home and installing or betterfying existing builder crap, if I ever build another house, it will be a custom design built to my specifications and not some box order build spec.

    EAC:
    I installed it because I and my young'ns suffer from allergies and thought this would help. I looked at the HEPA units (small duct mount ones) and it seemed they would not capture much air as it passed the unit. In addition to the EAC, we have installed allergy bed coverings and have already removed the carpeting on the lower portion of the house and installed hardwood. We are going to get estimates for upstairs area. Note; the allergy thing plays right into the wifees hand as she's been trying to get hardwood upstairs for years, so she may have me over a barrel now. Plus, I am addressing my allergies problems with the Immunotherapy (allergy shots) and hopefully can the get the young'ns squared away, too, and make this a moot point. If or when the units needs to be replaced, I will address all these concerns at that time.

    I will play with the wholehouse calculator, too.

    Again, thanks...Al

  11. #11
    Join Date
    Aug 2006
    Location
    Maryland
    Posts
    137
    Actually, I think the return was 20x16. I forgot to write it down - loosing it.

  12. #12
    Join Date
    Jun 2004
    Location
    Eugene, Oregon
    Posts
    1,018
    Quote Originally Posted by methodical View Post
    Question on Dampers: Air1, as far as dampers, I assume you are referring to the return air duct that will be added to the system. Correct me if I am wrong.
    Each branch duct off of the main return air trunk should have a balancing damper at or near where the branch duct connects to the main trunk.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten". --Benjamin Franklin
    "Don't argue with an idiot, they will drag you down to their level and beat you with experience". --Mark Twain
    http://www.campbellmechanical.com

  13. #13
    Join Date
    Aug 2006
    Location
    Maryland
    Posts
    137
    Got it. Can you recommend any particular unit?

    Thanks...Al

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