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  1. #14
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,721
    Quote Originally Posted by sktn77a View Post
    Thanks Beenthere - I think we're in violent agreement actually. Yes, I read Key1cc's thread back when it was active. Heat loads are calculated at a reference outside temperature, if the temperature falls below this reference, heat loss will be greater. While oversizing 2 stage equipment because installers are unable/unwilling to do a proper sizing calculation is bad, if the reference temperature heat loss lies between the two stages, that would appear to represent an ideal compromise between low stage comfort and high stage "reserve". Whether that's an 80,000BTU furnace or a 90,000 BTU furnace depends on the accuracy of the load calculation and the availability of sizes for any given manufacturer.
    First, those heat loss calcs have fudge factor built in - so don't add fudge to fudge.

    Second, unless your home has no thermal mass and tons of air leakage you don't even have to worry about design temp - it happens for such short periods. (*** Make sure you don't go for crazy setbacks when it gets really cold - your home may not move UP from 50, but it'll likely stay at 70)

    If it goes 20 degrees below design temp it'll take a LONG time for your furnace to NOT KEEP UP. In other words, the heat already built up in your house will be lost slowly over that period and MAYBE your 70 degree house will drop to 65 - after a few days. In that once in 50 years situation, if you want to keep 70 degrees - buy a couple space heaters.

    You want as low a second stage as possible - that's why high end furnaces now have a 3rd stage. MOST OF THE TIME 3rd stage is oversized! You want to get as close to properly sized for "most of the time" on your low stage.

    Don't spend more on equipment and more on energy for the next 20 years for a once in 50 year event that lasts a few days! Put a sweater on for heaven's sake! Get a blower door test to know your infiltration. Fix it if it's bad.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  2. #15
    Join Date
    Nov 2008
    Location
    Chapel Hill, NC
    Posts
    1,070
    Quote Originally Posted by tedkidd View Post
    Put a sweater on for heaven's sake!

    Ha! Tell my wife that!



    Keith

  3. #16
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,875
    Quote Originally Posted by sktn77a View Post
    Whether that's an 80,000BTU furnace or a 90,000 BTU furnace depends on the accuracy of the load calculation and the availability of sizes for any given manufacturer.
    In this case.
    Carrier does have the smaller furnace that already exceeds the load calc on high fire, with out going up to the larger furnace.
    Contractor locator map

    How-to-apply-for-Professional

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

  4. #17
    Join Date
    Jan 2009
    Location
    Springfield,Illinois
    Posts
    7

    Smile new system air and heating

    This message is to thank you guys for all your information very much appreciated............SKTN77a,b
    eenthere,Merlin73,Tedkidd and all others


  5. #18
    Join Date
    Jan 2009
    Location
    Springfield,Illinois
    Posts
    7

    Smile new system air and heating-update

    This is pictures of my install March 18,2009..........thanks guys.....sorry it took me so long to reply
    Attached Images Attached Images        

  6. #19
    Join Date
    Jan 2009
    Location
    Springfield,Illinois
    Posts
    7

    new system air and heating-update 2

    This is the outdoor unit..................Thanks

  7. #20
    Join Date
    Jan 2009
    Location
    Springfield,Illinois
    Posts
    7

    new system air and heating-update 2

    Sorry forgot to attach pictures............thanks

  8. #21
    Join Date
    Jan 2009
    Location
    Springfield,Illinois
    Posts
    7

    outside pictures of new install

    photos
    Attached Images Attached Images      

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