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  1. #1
    Join Date
    Mar 2008
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    Confused Help - too many opinions on new furnace and AC

    House is in Denver - 2 stories and finished basement - about 1300 square feet each on the main floor and upstairs, 800 sq. feet furnished basement (done about 15 years ago). Original Lennox furnace - 1976 - 165,000 Input BTU, 132,000 Bonnet cap BTU - furnace has done really well for us.
    We've had 5 people out, all reliable, and have gotten 5 different opinions.
    We want an 80% furnace, either 2-stage or variable - estimates have ranged from 100,000 BTUs to 150,000 BTUs. How can people be so far off???
    We want AC that's about 4 ton with SEER 13 (at least most agree that this seems about right - estimates have ranged from 3 1/2 to 5 ton). Everyone has done some kind of heat measurement, etc. and the numbers just don't agree so it's hard to know who to pick.
    Any thoughts on what BTU # seems right from info given?
    Any thoughts on 2-stage versus variable speed?
    We keep the house cool in winter, have pretty low utility bills compared to neighbors, and have no clue about AC since it is new to us.
    Someone also mentioned moving return duct upstairs to the ceiling of our bedroom - any thoughts on that?
    Thanks so much

  2. #2
    Join Date
    Dec 2007
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    Tough to say on your size issues without actually seeing the whole thing to do the proper calulations...however definately go with the Variable Speed motor....most furnaces that have a variable speed motor are already two stages.
    I need a new signature.....

  3. #3
    Join Date
    Jun 2006
    Hastings, MN
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    You need a manual J done, this is heat gain heat loss. Then have a manual D done this will size your duct work. No matter who sizes it this calc should be the same. There is no way to tell if it sounds right or not. They should not use rule of thumb. Something just don't sound right here. If they did load calcs there is only one answer. VS motor for sure best comfort.
    Aint Notin Sweeter, Then A Brand New Heater!!!!!!!!!!

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