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  1. #1

    No returns on 2nd floor

    Our house has no returns on the 2nd floor. Needless to say the air does not move well and upstairs is 5-7 degrees warmer in this heat. We don't have a good way to run returns to the basement from the 2nd floor. Our technician suggests that he zone the system. The thought is that when the 2nd floor is on but the first is off the pressure will cause the 2nd floor air to travel down the stairs and this draw the hot air downstairs.

    Seems reasonable but odd. Thoughts ?

  2. #2
    Join Date
    Aug 2001
    Location
    Pavilion, NY
    Posts
    2,020
    Done all the time. The key is that there is sufficient supplies upstairs to satisfy the cooling requirements. I have zoned dozens of systems and they all work well.
    ...

  3. #3
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,388
    You won't draw the hot air downstairs. Hot air is lighter than cold air. However you can deliver cold air to the 2nd floor and cool the hot air. The solution is to deliver enough air to the 2nd floor.

  4. #4
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,484
    Quote Originally Posted by kangaroogod View Post
    Done all the time. The key is that there is sufficient supplies upstairs to satisfy the cooling requirements. I have zoned dozens of systems and they all work well.
    X2

  5. #5
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,484
    Quote Originally Posted by kdean1 View Post
    You won't draw the hot air downstairs. Hot air is lighter than cold air. However you can deliver cold air to the 2nd floor and cool the hot air. The solution is to deliver enough air to the 2nd floor.
    Also...X2

  6. #6
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    2,731
    x3, with a warning...

    there has to be enough RETURN to satisfy the airflow requirements of the cooling load.
    it can be downstairs, but it'll need to be sized large enough to flow the air, and filter the load.

    make sure there is enough for 400cfm/ton of cooling, and 300Square inches of filter area per ton for modern filters.
    The TRUE highest cost system is the system not installed properly...
    The three big summer hearththrobs...
    Mel Gibson
    Dwane Johnson
    The A/C repairman

  7. #7
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    1,934
    Suggestion: Try first manually shutting all of the downstairs supply registers off and see what effect it has. This "should" give you some idea if the idea/suggestion will justify the money spent.

    As others have said, the equipment, no matter the modifications still has requirements that must be maintained for proper operation. If your contractor doesn't do the calculations ahead of time to verify that his modifications will allow for sufficient cooling of the 2nd floor while still maintaining the efficiency and reliability of the system then I would step back and look for other options.

    Not done correctly: Restricting air flow in half of the house to "pressurize" the remainder can cause premature failure of the blower motor. Can cause flooding of refrigerant back to the compressor leading to it's early failure. Can cause the indoor coil to freeze up. Can result in excessive electric bills with limited comfort to show for it.

    Granted, getting return air duct work to the 2nd floor of a home is not an easy task nor is it inexpensive to do. But, getting the right sized return to the second floor and doing it right will do the best job of cooling that floor. You're looking at spending X amount of money to zone the home verses X amount of money to install 2nd floor returns.

    Just to throw another option into the mix. This expenditure could be put towards installing a seperate system for the 2nd floor either in the form of standard forced air or a mini-split system. Just a thought.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

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