Results 1 to 5 of 5
  1. #1
    Join Date
    Jul 2016
    Posts
    3
    Post Likes

    Strong AC air flow upstairs, weak downstairs

    I'm no HVAC expert; forgive any wording errors. I have just moved into a 150-year-old, 2 story house with central air. Condenser unit on ground level, air handler in basement (hybrid with gas furnace). Vents on floor downstairs, in ceiling upstairs. No easily accessible attic. 2 air intakes: 1 30'x40' near floor downstairs. 1 larger one near ceiling upstairs. The air flow is good downstairs and weak (and not as cool) upstairs. Not surprisingly, in summer it's much warmer upstairs. If I block downstairs vents with books, the airflow improves a little upstairs and the temperature equalizes, but I have read many places that this is a bad idea. I understand that a major problem with blocking vents is the pressure imbalance this creates between intake and outflow. Is it possible that blocking the downstairs intake as well as some or all of the downstairs vents would rebalance the pressure? I have sunk every penny into my downpayment and cannot afford major AC work right now. Thank you.

  2. #2
    Join Date
    Sep 2012
    Location
    Missouri
    Posts
    401
    Post Likes
    Check around the AH ducts for balancing dampers.

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    6,627
    Post Likes

    Does the title read wrong?

    I am reading a conflicting message; the title reads one way and the posted content reads as though the airflow upstairs is weaker and it is hot upstairs because you're talking about blocking off downstairs supply air registers.

    Have an airflow expert evaluate the situation.
    You could block off the downstairs return, the upstairs return and return air filter are both large enough, then make sure you have sufficient supply air ducting and registers going to the upstairs so that the system could deliver more airflow upstairs then downstairs.

    How much CFM airflow does the A/C require?
    Example; a 3-Ton requires around 1200-CFM; the ratio between upstairs & downstairs should deliver that amount; or 400-CFM per Ton of Cooling.

    The above is just one of the simpler versions there are other ways to solve the problem...

  4. #4
    Join Date
    Jul 2016
    Posts
    3
    Post Likes
    Thread Starter
    You're absolutely correct. I'm sorry. The title has it backwards. I think that I cannot edit it at this point. If I can, please tell me how.

    I cannot see CFM or tons on the units. The Air Handler is a Carrier model cnpvp3017. The compressor is a Carrier 24APA530A300, which from what I've read might mean it's 2.5 tons. What does that suggest?

    6 registers upstairs. 8 downstairs.

    I think you are sort of agreeing with me that it may be possible to block the downstairs return as well as the downstairs registers without suffering some of the efficiency, pressure and air-flow problems that normally occur when people block registers only?

  5. #5
    Join Date
    Jul 2016
    Posts
    3
    Post Likes
    Thread Starter
    Thanks for the suggestion. I checked, and if I follow the ducts, it looks to me as if one damper controls ducts that go to 2 downstairs registers and the other leads to every other register: 6 more downstairs and 6 upstairs. So that configuration means the dampers cannot help much in my situation, I think.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •