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Thread: Need to upsize?

  1. #1
    Join Date
    May 2005
    Location
    Indianapolis, IN
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    255
    What information does one need to know whether or not their A/C and/or furnace is undersized?

    My house is 2500sq. ft. I have 10 4x10 registers, 2 2x10 registers, and 1 6x10 register. I have 2 5" pipes connected behind a 30x6 grill and one 20x10 return.

    Currently I have a 15 year old 75,000 BTU furnace and a 2 ton A/C unit.

    I can get you more info if someone needs it but my question is is this enough?

  2. #2
    Join Date
    Aug 2002
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    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    A load Calulation is the best way to know what size is needed,Manual j,from ACCA,or the equivalent like the one on this site.just click on the bulseye above ,and for a small fee you can do it yourself.If not there,then call a Pro,and be sure to tell them you want a Mna. J,some can do it and some can't.

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,987

    Exclamation Location Location Location

    Originally posted by chrashley
    My house is 2500sq. ft. I have 10 4x10 registers, 2 2x10 registers, and 1 6x10 register. I have 2 5" pipes connected behind a 30x6 grill and one 20x10 return.

    I can get you more info if someone needs it but my question is is this enough?
    Do you live in Alaska or Canada?
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  4. #4
    Join Date
    Jun 2005
    Posts
    83
    Originally posted by dash
    A load Calulation is the best way to know what size is needed,Manual j,from ACCA,or the equivalent like the one on this site.just click on the bulseye above ,and for a small fee you can do it yourself.If not there,then call a Pro,and be sure to tell them you want a Mna. J,some can do it and some can't.
    This is GREAT advise. Call for a contractor who will do a J manual load. This can determine what size you need for where you live.

  5. #5
    Join Date
    May 2005
    Location
    Indianapolis, IN
    Posts
    255

    Re: Location Location Location

    Originally posted by dan sw fl
    Originally posted by chrashley
    My house is 2500sq. ft. I have 10 4x10 registers, 2 2x10 registers, and 1 6x10 register. I have 2 5" pipes connected behind a 30x6 grill and one 20x10 return.

    I can get you more info if someone needs it but my question is is this enough?
    Do you live in Alaska or Canada?
    Sorry for the delayed response but...

    What do you mean by this? I live in Indiana.

  6. #6
    Join Date
    Jul 2002
    Posts
    962
    You have been given good advice, there is not much one can tell you without more information. Just do the load calc or have some one do it for you.

    BTW, why do you suspect undersized? Have you had anyone come out and check the unit?

  7. #7
    Join Date
    May 2005
    Location
    Indianapolis, IN
    Posts
    255
    I'm an installer and I know what I put in houses that are roughly the same size as mine. With this equipment being as old as it is I'm sure the efficiency of it has depreciated. Plus, the equipment seems to be working fine (just running all the time), the charge is good (I believe). It just seems that the coil is doing all it can but just can't get the temps down. Don't you think that a 2 ton coil seems a bit small for a 2500 sq. ft. home? What other information do you need...I'll be more than happy to try to get it for you.

  8. #8
    Join Date
    Feb 2005
    Location
    Dothan, Al
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    3,453

    chrash

    I do believe that 2 ton is too small for 2500.
    At least here in south -
    Questions: What temp are you trying to maintain? What are outdoor temps? What is actual temp in home? Is there a difference in temps between areas. What temp is coming out if registers ?

    Richard

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,764
    Click on the bulls eye, and do you own load calc.
    Then you'll know what size your house needs.

    You'll also learn more about our trade.

    Contractor locator map

    How-to-apply-for-Professional

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

  10. #10
    Join Date
    Jul 2002
    Posts
    962
    I don't think I have seen any 2 ton systems on that size house but I don't live in Indiana, nor can I see the house from here. There are so many factors that go into sizing a system. Which you will see when you buy the software for your load calc. How long have you been living there? do you know anything about the past performance? If you are thinking of replacing this old system, then the load calc is a great way to be sure.

  11. #11
    Join Date
    May 2005
    Location
    Indianapolis, IN
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    255
    I just moved in to the house about two weeks ago. I've been busy doing all kinds of stuff so I haven't had a chance to get too much into one problem (i.e. cooling the house down.) so I don't know temps at the registers and returns but I'm trying to keep the house at about 72 with it being in the mid to high 90's outside. The heat indexes have been up to about 105 but really have been averaging about 98-100. At night though it's been getting down into the high 60's. So that gives my A/C time to catch up. So in the morning when I leave for work the temp reading on the stat is around 70. But when I get home the furnace is struggling to keep it at 80. Plus at night once the temps start dropping it still takes it FOREVER for it to finally get down to where the A/C can shut off for a minute. So basically from probably 8:00 am till 3:00 am the next day the A/C is running all the time. And yes the house is definately warmer on the upper floors than in the main and basement floors. Also what could it mean if there is a short "hum" coming from the outdoor unit. Every so often the outdoor unit makes this hum that lasts about two seconds and then goes away. I wonder if that has something to do with the problem. I just find it hard to believe that with my house being 15 years old that someone didn't upsize the equipment before now. Don't you think that if the unit was undersized that there would have been a problem all along and someone would have had it fixed?

  12. #12
    Join Date
    Jul 2002
    Posts
    962
    I would check out the system first, make sure its charge is right and air flow is in the right range. Then see where that points you. I have seen systems that never ran right, and people just live with it. Who knows!

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    The former owners may have ben happy with 80 temp in the house.

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