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  1. #1
    Join Date
    Apr 2006
    Posts
    80

    Thought my home was tight?

    Very hot....it was 109 here today. I have a Carrier 16 seer 4 ton infinity heat pump. My home is a 2000 sq ft home with high celings. Set thermostat at 77, and it held there until 3:00p.m.. Then it went to 80 and has not come down yet. I have my unit serviced twice a year and just had it done. Measured the temp out of the return and intake. There is a 18 degree difference at the moment. Since its close to 20, I assumed that its doing its job. So, to my question. If my temp difference is 20, why cant my unit keep up?

  2. #2
    Join Date
    Jan 2008
    Posts
    1,858
    Outdoor temp is above design temp?
    If it is, then your system is probably sized right, and performing properly.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  3. #3
    Join Date
    Apr 2006
    Posts
    80
    Quote Originally Posted by 2old2rock View Post
    Outdoor temp is above design temp?
    If it is, then your system is probably sized right, and performing properly.
    I have been told that our design temp for our area is 100.

  4. #4
    Join Date
    Jun 2001
    Location
    DFW
    Posts
    683
    I know my home is tight.
    4,000 sq. ft. 2 ton heat pump, 108 outside, 73.8 inside.

  5. #5
    Join Date
    Dec 2007
    Location
    houston, texas
    Posts
    3,787
    Quote Originally Posted by paul42 View Post
    I know my home is tight.
    4,000 sq. ft. 2 ton heat pump, 108 outside, 73.8 inside.
    It's either the tightest home in Texas or your pulling my leg, 2 tons isn't gonna do much on 4000 sq ft, much less in Dallas
    I'm not tolerating Political Correctness anymore, from now on it's tell it like it is.

    Veto Pro Pak - The best tool bag you'll ever own






  6. #6
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    Quote Originally Posted by kkmcewen View Post
    I have been told that our design temp for our area is 100.
    If your design temp is 100 and its 109 and you are 3 degrees above your set point, you are doing good.
    Karst means cave. So, I search for caves.

  7. #7
    Join Date
    Jun 2001
    Location
    DFW
    Posts
    683
    Quote Originally Posted by Texas-Tech View Post
    It's either the tightest home in Texas or your pulling my leg, 2 tons isn't gonna do much on 4000 sq ft, much less in Dallas
    Put the air handler & duct work in conditioned space.
    Shade all the windows in the summer.
    Make the house air tight.

    West end of Fort Worth.
    Upstairs, it is 73.9, downstairs is 68.

  8. #8
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    3,586
    Your system is designed to deliver its rated btu's up to 100 degrees outdoor temp. . Anything over that emp decreases the output. Basically you have enough btu output to maintain temp at 80, but not enough to bring the temp down...unless you live in a styrofoam house.

  9. #9
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,460

    Lightbulb

    Quote Originally Posted by kkmcewen View Post
    Very hot....it was 109 here today. I have a Carrier 16 seer 4 ton infinity heat pump. My home is a 2000 sq ft home with high ceilings. Set thermostat at 77, and it held there until 3:00p.m.. Then it went to 80 and has not come down yet. I have my unit serviced twice a year and just had it done. Measured the temp out of the return and intake.

    There is a 18 degree difference at the moment. Since its close to 20, I assumed that its doing its job. So, to my question. If my temp difference is 20, why cant my unit keep up?
    The percent relative humidity has the biggest affect on the indoor temp-split.
    The higher the humidity the lower or lesser the sensible temp-split; the lower the humidity the higher the temp-split.

    Regarding the indoor split; a higher indoor temp has a much lesser affect than a high humidity level on reducing the split. With a rather high humidity latent heatload a 12 or 14-F temp-split could still indicate a properly operating system.

    The 109-F outdoors will reduce the BTUH output of the condenser, maybe a little water misting would help, if combined with a TXV metering device on the indoor coil.

    The indoor airflow CFM if too low, in a relatively dry climate, will reduce BTUH performance of the indoor coil.

  10. #10
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,402
    Quote Originally Posted by Texas-Tech View Post
    It's either the tightest home in Texas or your pulling my leg, 2 tons isn't gonna do much on 4000 sq ft, much less in Dallas
    Maybe 2500 of that is an unconditioned garage? I find it hard to believe as well. 2000 sq. ft. per ton? Holding 74 at 109? I've worked on some pretty efficiently built houses and 1000 sq. ft. per ton in Texas is really pushing it.
    I like DIY'ers. They pay better to fix.

  11. #11
    Join Date
    Oct 2004
    Location
    So Cal
    Posts
    3,306
    Quote Originally Posted by paul42 View Post
    I know my home is tight.
    4,000 sq. ft. 2 ton heat pump, 108 outside, 73.8 inside.
    Not in your wildest dreams

  12. #12
    Join Date
    Jun 2009
    Location
    Northwest IN/Chicago
    Posts
    268
    Quote Originally Posted by paul42 View Post
    Put the air handler & duct work in conditioned space.
    Shade all the windows in the summer.
    Make the house air tight.

    West end of Fort Worth.
    Upstairs, it is 73.9, downstairs is 68.
    Are you sure that's not two two ton units? Either way I would love to know your secret. Even if it is perfectly shaded and insulated, sealed etc that still sounds crazy.

  13. #13
    Join Date
    Jul 2002
    Location
    Yuma, AZ
    Posts
    2,361
    kkmcewen, Where are you located? Climate matters, especially humidity (As Udarrel was pointing out).
    paul42, That is hard to believe because we expect "normal construction".
    • A home that size in a simple rectangle of 40'x50' with two stories would have a minimum gross wall area of 5760 sq.ft.
    • The typical window area is 10 to 15% of wall area so the minimum window area for non cave dwellers would be about 576 sq. ft.
    • The volume of the home is at least 32000 cu. ft, and the recommended air changes per hour for IAQ reasons is .35 or 11,200 cfm per hour (187 cfm).

    Tell us more about the home construction. Is it subterranian? Do you have windows and doors? How are they constructed? Do you have the recommended ACH? Do you have an ERV or HRV?
    "I have never let my schooling interfere with my education."
    Mark Twain
    More at: http://www.quotationspage.com/subjects/education/

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