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  1. #27
    Quote Originally Posted by beenthere View Post
    How much insulation is in that cathedral ceiling.

    Lot of radiant heat from them.
    I'm guessing no air to temp the air at the ceiling. And no return near it either.

    Realizing you have both a lot of time and money typed up in your house.
    A blower door test would be a good idea, to find out how tight it realy is.
    Then a load calc. To get the right size unit to replace the 3 ton.
    The cathedral ceiling is SIP (Structural Insulated Panel) at R49... There is a set of air returns near where the roof meats the upper wall, but only at one end of the house... (aside: in a timber frame home with an open plan, there is a criminal lack of wall space to put returns and such)

    And energy audit would be a good idea... if we could afford it... and i doubt the HVAC company is going to even bother calculating... If i end up making them take it all out, I will make sure the next contractor does his homework.

    Most of the air leakage will be in the second story, stick framed portion... (which i regret skimping on). Next house will be totally SIP.

  2. #28
    Join Date
    Jun 2001
    Location
    DFW
    Posts
    684
    I prefer to fix the sturcture first, and then fix the HVAC equipment only as necessary.

    How many windows are getting direct sun? Can you add solar screens?
    Find someone that can do a blower door test on your house.
    Replace any standard bulbs with compact flourescents where possible.

    A SIP house should be doing a LOT better than what you are seeing.

    My house in North central Texas, 2,230 sq. ft. up, 1,800 sq. ft down, and my 2 ton heat pump will cool the house down to 70 degrees when it is 101 outside. Frame construction throughout.

  3. #29
    Quote Originally Posted by paul42 View Post
    I prefer to fix the sturcture first, and then fix the HVAC equipment only as necessary.

    How many windows are getting direct sun? Can you add solar screens?
    Find someone that can do a blower door test on your house.
    Replace any standard bulbs with compact flourescents where possible.

    A SIP house should be doing a LOT better than what you are seeing.

    My house in North central Texas, 2,230 sq. ft. up, 1,800 sq. ft down, and my 2 ton heat pump will cool the house down to 70 degrees when it is 101 outside. Frame construction throughout.

    I only have 3 windows with a southern exposure (the other are under a covered porch. however one is very large over the great Room (5' x 7.5') but is Low e with argon filled... I do suspect that is part of the problem. the other two are in the upper bed rooms, and those rooms have their own problems and are not used more than a couple times a year)


    How tall are your cielings?

    It think that the hybrid nature of my house is skewing everything. I really should have sipped the whole thing.

  4. #30
    Join Date
    Jun 2001
    Location
    DFW
    Posts
    684
    Quote Originally Posted by jackfalstaff View Post
    I only have 3 windows with a southern exposure (the other are under a covered porch. however one is very large over the great Room (5' x 7.5') but is Low e with argon filled... I do suspect that is part of the problem. the other two are in the upper bed rooms, and those rooms have their own problems and are not used more than a couple times a year)


    How tall are your cielings?

    It think that the hybrid nature of my house is skewing everything. I really should have sipped the whole thing.
    Ten foot ceilings on the main floor.

    There are four big factors that influence how much AC you need.
    1. Air infiltration
    2. Solar gain through the windows
    3. duct work & air handler in unconditioned space
    4. Insulation

    The height of the ceiling is so far down on the list as to be almost negligible.

  5. #31
    Quote Originally Posted by paul42 View Post
    Ten foot ceilings on the main floor.

    There are four big factors that influence how much AC you need.
    1. Air infiltration
    2. Solar gain through the windows
    3. duct work & air handler in unconditioned space
    4. Insulation

    The height of the ceiling is so far down on the list as to be almost negligible.
    Here is what i have:

    1. Air infiltration is really only possible on the second floor. I am going to start looking for it.

    2. Solar gain really should not be too bad, apart from the 1 large window, and there is not much more we can do with that one... i was at least smart enough to put most of them under the porch.

    3. All the duct work is in the crawl space, and is insulated, so especially for summer, is should be good.

    4. Insulation: I am going to go up and check. I had a "friend" put it in. (he is a former friend now, because he screwed us on a lot of stuff on the house) I am going to verify that he put in as much as he said he did, over the 2 2nd floor wings.

  6. #32
    Quote Originally Posted by paul42 View Post
    I prefer to fix the sturcture first, and then fix the HVAC equipment only as necessary.

    How many windows are getting direct sun? Can you add solar screens?
    Find someone that can do a blower door test on your house.
    Replace any standard bulbs with compact flourescents where possible.

    A SIP house should be doing a LOT better than what you are seeing.

    My house in North central Texas, 2,230 sq. ft. up, 1,800 sq. ft down, and my 2 ton heat pump will cool the house down to 70 degrees when it is 101 outside. Frame construction throughout.
    Paul,

    I think you may be right. I think i will start hunting for infiltration and places to tighten up. It seems to me, that the system may be pretty close to being right. And if I can work on tightening up the house, it might end up better off. At least i should try and if i still have a problem, it will be up to the HVAC company to fix. I have 1 year after install to reject the system if not satisfied.

    To be honest, when i used hvac calc to estimate my heat/cooling needs, i came up with needing only 2.5 tons for cooling. So something isn't matching up to expected r-values and air infiltrations. And i am pretty sure it is not the SIP's.

  7. #33
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,330
    Is your crawlspace sealed.
    Duct leakage can have big effects on your heating and cooling.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #34
    Quote Originally Posted by beenthere View Post
    Is your crawlspace sealed.
    Duct leakage can have big effects on your heating and cooling.
    what do you mean by sealed? All the duct work is insulated, if that is what you mean..

    other than that it is your standard pea gravel filled, vented 4 ft crawl.


    btw: They just called to say they are going to come tomorrow to do a load test.. . or something like that... I guess now they are going to do the math...

  9. #35
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,330
    I meant is the crawlspace itself sealed. And it isn't.

    It doesn't take much duct leakage to reduxe your systems ability to heat or cool your house.

    If your pulling in unconditioned crawlspace air, your HP has to work harder. If your supply is leaking to the crawlspace. It increases your homes infiltration.

    Never hurts to check the duct in the crawlspace yourself.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  10. #36
    Quote Originally Posted by beenthere View Post
    I meant is the crawlspace itself sealed. And it isn't.

    It doesn't take much duct leakage to reduxe your systems ability to heat or cool your house.

    If your pulling in unconditioned crawlspace air, your HP has to work harder. If your supply is leaking to the crawlspace. It increases your homes infiltration.

    Never hurts to check the duct in the crawlspace yourself.
    will do... Thanks for all the info..

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