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  1. #14
    Join Date
    Nov 2006
    Location
    Mechanicsburg, PA
    Posts
    310
    you have more problems than the unit not cooling. When it does get fixed it will never be comfortable. 3.5 ton for a house <1900 sq ft. In a brand new home a 3.5 ton should be about 4000 sq ft if not larger. If this in the basement or attic? Is it mounted on top of a furnace? Maybe a lot of air is leaking around the base of the coil.
    Is the outdoor unit running continuously?

  2. #15
    Join Date
    Jul 2009
    Posts
    12
    Quote Originally Posted by rbeck View Post
    you have more problems than the unit not cooling. When it does get fixed it will never be comfortable. 3.5 ton for a house <1900 sq ft. In a brand new home a 3.5 ton should be about 4000 sq ft if not larger. If this in the basement or attic? Is it mounted on top of a furnace? Maybe a lot of air is leaking around the base of the coil.
    Is the outdoor unit running continuously?
    so your saying the unit should be big enough for the house then?? also yes once 2pm hits the unit will run all afternoon up until late in the night prob 10 or 11 pm

  3. #16
    Join Date
    Nov 2006
    Location
    Oregon
    Posts
    853
    Quote Originally Posted by ZacHolley View Post
    so your saying the unit should be big enough for the house then??
    The only way to quantify that the unit is sized properly is by a detailed load calculation. (ex: Manual J)

  4. #17
    Join Date
    Jul 2009
    Posts
    12
    Quote Originally Posted by davefr View Post
    The only way to quantify that the unit is sized properly is by a detailed load calculation. (ex: Manual J)
    how do you do that?

  5. #18
    Join Date
    Nov 2006
    Location
    Oregon
    Posts
    853
    Quote Originally Posted by ZacHolley View Post
    how do you do that?
    The HVAC contractor should have done that when sizing the system for the home.

    It's a very detailed analysis that takes into account:
    1.Your local climate including temperature and humidity patterns
    2. The design of your home such as square footage, stories, ceiling heights, windows and direction they face, roof overhange, etc.
    3. Construction of your home such as insulation R-values, etc
    4. Ductwork. (vents and returns, numbers of them and sizes)

    The end result of all this data helps the contractor pick the right size system.

    I would ask the manager how did they arrive at the capacity of the system. If they estimated (ie guessed) then that would be a red flag!! If they did a detailed analysis, they should double check the data as part of the overall troubleshooting process.

  6. #19
    Join Date
    Jul 2009
    Posts
    12
    Quote Originally Posted by davefr View Post
    The HVAC contractor should have done that when sizing the system for the home.

    It's a very detailed analysis that takes into account:
    1.Your local climate including temperature and humidity patterns
    2. The design of your home such as square footage, stories, ceiling heights, windows and direction they face, roof overhange, etc.
    3. Construction of your home such as insulation R-values, etc
    4. Ductwork. (vents and returns, numbers of them and sizes)

    The end result of all this data helps the contractor pick the right size system.

    I would ask the manager how did they arrive at the capacity of the system. If they estimated (ie guessed) then that would be a red flag!! If they did a detailed analysis, they should double check the data as part of the overall troubleshooting process.
    well ask him if ya would because i almost feel like it must need a 4 ton unit or somthing because we have hot days over 100 most of the summer and also i have 10foot ceilings throughout

  7. #20
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    They don't have building and mechanical inspection departments in OK? In our area, you can't build a chicken coop without supplying the building inspection department with detailed plans including results of Manual J and Manual D in data and schematic format.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  8. #21
    Join Date
    Jul 2009
    Posts
    12
    Quote Originally Posted by heaterman View Post
    They don't have building and mechanical inspection departments in OK? In our area, you can't build a chicken coop without supplying the building inspection department with detailed plans including results of Manual J and Manual D in data and schematic format.
    I don't know what they have here??

  9. #22
    Join Date
    Jul 2006
    Posts
    6,502
    I had a friend who worked for a builder. I asked a few times about who i could talk to about doing the work. He told me several times i did NOT want to do this type of work.
    One day we stopped by a home under construction.
    The indoor system consisted of.
    1 central return
    furnace,plenum,take off and the rest of the system was flex besides the tees and reducers. I almost puked.
    This work was done by a company 100 times bigger than mine.
    these were not cheap houses.
    He told me that they get complaints as soon as the people move in.
    You sure are cocky for a starving pilgrim.

  10. #23
    Join Date
    Jan 2007
    Location
    N.E. Ok.
    Posts
    1,370
    I don't know what they have here??
    If you are in a small municipality you may have a combined inspection that is performed usually by a city employee who isn't lic. in all trades.
    Regardless all mech. contractors are lic. through the state (C.I.B.) and he is responsible to uphold all codes layed out in the I.M.C. 2006 (unless superceded by a local code)

    Properly vented attic spaces are a must as most equip. and duct is there.

  11. #24
    Join Date
    Jul 2009
    Posts
    12
    That is another thing the only ventilation for the attick is saufet vents every 6 foot all the way around the house shouldn't it have turbines or something?

  12. #25
    Join Date
    Jan 2007
    Location
    N.E. Ok.
    Posts
    1,370
    Lots of good reading in several threads, here is 1 for you http://hvac-talk.com/vbb/showthread.php?t=166795

    Radiant barrier roof decking with ridge vent combined with the soffit vents all sized properly work real well.

  13. #26
    Join Date
    Aug 2006
    Location
    Marco Island, Fl
    Posts
    729
    You obviously live in a warm area. In my area, system design is based in 95 degree outdoor temp, 75 degree indoor temp. This is often referenced as "Design Split". This means when it is 95 outside, the system will maintain 75 inside.

    Your system does not sound oversized for a warm area, and may be undersized for what you want it to do.

    Your builder may have had a manual J load calc done, and this will tell you the design split. Equipment selection is also important, to be sure it will put out the required capacity at warm outdoor temps.

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