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  1. #1
    Join Date
    Jun 2004
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    St Paul, minnesota
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    1,170

    80% variable speed, modulating gas furnace

    I also posted this in pro residential forum

    80% variable speed, modulating gas furnace
    Is there such a thing out there. I know Carrier Infinity makes a three stage gas variable speed 80% furnace, but any mfr make a mod gas heat. I know why not go to 90+%. in this case not an option as furnace room in center of a finished basement and customer won't allow any wall demolitions and won't change out the water heater to power-vent (I also thought of that). Is Carrier/Bryant only ones with more than 2 stage gas, variable speed 80%?

  2. #2
    Join Date
    Sep 2008
    Location
    VA
    Posts
    1,762
    Most modulating furnaces are controlled by pressure differential gas valves, sealed combustion, and a variable speed draft motor.
    A modulating 80% gas furnace would probably cost more than a 2 stg 95% furnace. What would be the point? Especially with the fact that 80% may be phased out in the near future. The cost of research & development would not pay dividends to the manufacturer.

    I believe York uses a stepper gas valve, so maybe they have one?
    Yep, just looked it up, I think the YPLC is the model.
    "The only true wisdom is in knowing you know nothing" Socrates

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
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    34,089
    Carrier doesn't have anything more than a 2 stage 80.

    http://www.yorkupg.com/residential/p...unit-yplc.aspx

  4. #4
    Join Date
    Jun 2004
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    St Paul, minnesota
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    Quote Originally Posted by BaldLoonie View Post
    Carrier doesn't have anything more than a 2 stage 80.

    http://www.yorkupg.com/residential/p...unit-yplc.aspx
    Hey BaldLoonie

    can you send me the install manual as I don't have a current password access to upg.net anymore

  5. #5
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,221
    Shouldn't a water heater be power vented if it's connected to an 80% furnace? If the customer is concerned about overshooting with each cycle go 2 stage and get the capacity as close to load as possible.

  6. #6
    Join Date
    Jun 2004
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    St Paul, minnesota
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    Quote Originally Posted by 54regcab View Post
    Shouldn't a water heater be power vented if it's connected to an 80% furnace? If the customer is concerned about overshooting with each cycle go 2 stage and get the capacity as close to load as possible.
    I don't know where you are from, but in my neck of the woods we always use a natural draft water heater with a 80% furnace vented into a common vent system of course vented correctly. power vented water heaters use pvc pipe for venting. Already did load calc, not worried about overshooting, a mod furnace is more about comfort than energy savings as it will run longer that a 2 stage

  7. #7
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,221
    Quote Originally Posted by superfittertech View Post
    I don't know where you are from, but in my neck of the woods we always use a natural draft water heater with a 80% furnace vented into a common vent system of course vented correctly. power vented water heaters use pvc pipe for venting. Already did load calc, not worried about overshooting, a mod furnace is more about comfort than energy savings as it will run longer that a 2 stage
    It's against code here to have a power vented furance and natural draft water heater sharign the same flue. Oversizing of furances is a huge issue in Oklahoma here since it doesn't get that cold. It isn't uncommon to see 100K furances in 2,000sqft houses even though design temp is only 17. Rarely do furnaces ever run over 50% of the time, even at design conditions.

  8. #8
    Join Date
    Jun 2004
    Location
    Olean, NY
    Posts
    1,449
    The 80 percent furnace should be in a flue liner I'm sure.

    Sent from my MZ601 using Tapatalk
    Guinness for strength

  9. #9
    Join Date
    Jul 2007
    Location
    Virginia
    Posts
    5,519
    Quote Originally Posted by superfittertech View Post
    Hey BaldLoonie

    can you send me the install manual as I don't have a current password access to upg.net anymore
    I sent one your way.
    Instead of learning the tricks of the trade, learn the trade.

  10. #10
    Join Date
    Dec 2011
    Location
    somewhere between here and there
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    478
    80% furnace is not power vented
    it is induced draft
    the inducer motors job is just that....induce a draft
    if u put manometer 18" downstream of furnace exhaust u will find vacuum, not pressure


    Please, Please Please......keep the Factory Smoke in the Wires!!!!!


    Is it Rum'Oclock yet???

  11. #11
    Join Date
    Jun 2004
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    St Paul, minnesota
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    Quote Originally Posted by BigBacardi View Post
    80% furnace is not power vented
    it is induced draft
    the inducer motors job is just that....induce a draft
    if u put manometer 18" downstream of furnace exhaust u will find vacuum, not pressure
    X2

    didn't want to try to argue with them as they didn't get it.

  12. #12
    Join Date
    Jun 2004
    Location
    St Paul, minnesota
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    1,170
    update after getting info for the York/Coleman YPLC furnace. Not only does it have a variable speed fan it also has variable speed inducer fan and modulating gas down to 50% capacity

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