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  1. #1
    Join Date
    Jan 2006
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    Whats the pros and cons of 2 stage VS. Single stage gas furnaces???

    My home is an older home with single pane glass walls in Southern California. I'm thinking the two stage may be a better choice for my application.

    thanks in advance.........Geno

  2. #2
    Join Date
    Jun 2004
    4H: Hot, Humid Houston H.O.
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    Two stage heat is very mild

    I am a homeowner, which may actually make me more qualified to answer this particular question, than a pro HVAC person. I have a 2-stage American Standard gas furnace, in a 1989 house with large amounts of single pane windows. You could expect the furnace to be working very quietly on first stage when the weather is cool but not cold, with the high stage coming on only occasionally in colder weather.

    From the tone of your question I expect the price premium is not a great big deal to you. That is a prerequesite, as you can get 1-stage furnaces cheaper. For me a big attraction was the variable speed (VS) air handler, with its better ability to adapt to mediocre ductwork. And I wanted to keep the option open for a possible 2-stage AC, which requires the VS air handler. Those reasons may or may not apply to you.

    A big variable is the size of your furnace vs. your house's actual heating needs. My house is estimated to need 85-90 thousand BTU/Hr, and with its AC needs they don't make furnaces small enough to be a great fit. So I have 128K furnace capacity or about 50% larger than I need according to ACCA Manual J. With this setup, I get all my heat needs met without *ever* going on to the high stage heating. If you had a furnace closer size to your needs, you might see the high stage run but I bet it would be seldom.

    Our cold climate comes and goes, rarely lasting more than a short time (while our summer heat arrives and just sits on us for half a year). If your winter climate is at all like that, I think you would find the two-stage furnace to be a very quiet and unobtrusive way to heat your house.

    Once in awhile you hear of someone who actually prefers a blast of hot air to heat their home in winter. I assume that is not your style, there are all sorts of opinions.

    Best of luck -- Pstu, aka 'P.Student'

    [Edited by pstu on 01-26-2006 at 06:09 PM]

  3. #3
    Join Date
    Jan 2006
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    what every you choose go 90+ vs 80

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