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  1. #1

    How many tons do I really need?

    I have a 3 level exposed basement house (3600 square feet). No time is spent in the basement and most of our time is spent on the main floor. Upstairs mainly for sleeping. We currently have a 3 ton that needs to be replaced. My options are 1) simply replace the 3 ton, 2) zoning with 1 system and 2 t-stats and 3) 2 seperate systems.

    2) zone 1 would be basement and main floor (2400 sf), zone 2 the upstairs. Do I stay with the 3 ton (variable speed, 2 stage) or move up to a 3.5 ton (variable speed, 2 stage) as recommended? House cools fine with a 3 ton, I just want the added benefit of 2 t-stats and upgrading to a better 3 ton.

    3) The 2 systems would be dedicated as layed out for zoning. Being told to use a 2.5 ton for the 2 bottom floors and 2 ton for top floor. Is this too much? Will a 2 ton for each system work just as well?

    One company said zoning would work fine on our house (said that is what he would do if it was his house). The other guy said zoning wouldn't work with our layout. 3rd guy coming out on Friday. Any thoughts?

  2. #2
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    Have any of these contractors run a manual J to see just what size system you need?

    Without seeing the house its hard to tell what design of a system might work.
    Its a good Life!

  3. #3

    No programs have been ran

    The one will only run the program when we are ready to commit. Seemed fishy to me since I need quotes in order to commit.

    The other guy is basing it on his best-quess. This guy is the higher ton guy.

    I don't want to commit to a higher ton if that is not what we need.

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,931
    If 3 ton does the trick, it would be nuts to go bigger. I'd remove that guy from consideration! Most duct systems aren't sized for what you have let alone going bigger! Going to 4.5 ton with 2 systems sounds even nuttser

    As for zoning with existing ducts, can be tricky. Usually better for zoning if duct system is designed with that in mind.

  5. #5
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,426

    Smile size and zoning?

    If you were adequate with the 3 ton, it would be totally nuts to go with a 3 1/2 ton, especially if you zone the house. Someone should have enough knowledge to do a simple maual J. (There are "fill in blank" forms for goodness sakes!) If the ductwork is accessible, and seperate for each floor, the zoning would work, but still would recommend the J figures, because with zoning you might be able to use a 2 1/2 ton unit and still get good results!

  6. #6
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    If your existing system works OK, then why not just replace it with a similar system. Do you have large differences in temperature between the three levels?

  7. #7

    exsisting system

    sometimes there is a 5 degree difference between the 3rd floor and the 2nd floor. Not sure about the basement, but my parents didn't complain when they stay in the quest bedroom during the winter. There is only 1 damper and that is for the 3rd floor ducts. Not 100% sure that it has been set in the proper position though. Also, we have had electric bills in the $700 range in the winter and $500 in summer. Again, no one can tell me if the size of the unit is to blame or the way our system is set up. Just don't want to be sucked into the highest priced option to get things running right.

    I just have one guy saying he can't believe we only have a 3 ton and another guy saying the 3 ton should work fine for our set up. From everyone's responses, it sounds to me that the first guy is just trying to get us into a more expensive option and a 3 ton is fine. Now if I can only get the other guy to run the program without commiting first.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,776
    Zoning would probably take care of the uneven temps.
    Uneven temps is seldom caused by equipment being too small.
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