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  1. #1
    Join Date
    Mar 2005
    Posts
    2
    We're installing a new system and will be getting an 80% furnace that is two stage, or variable. Have not had luck in researching what exactly, besides cost, is the difference. We've been told the variable is quieter, more efficient...anyone have real world experience w either of these? Wondering if it's worth getting the variable or not.

  2. #2
    Join Date
    Nov 2001
    Posts
    1,874
    You didn't put where you live in your profile,
    So no-one here can say whats best for you.

    Depending on your climate, an 80% may well be all you need.
    An 80% 2 stage will save on gas consumption, a variable speed will save on electrical consumption, and give slightly more comfort if the ductwork is correct.
    If you try to fail, and succeed.
    Which have you done ?



  3. #3
    Join Date
    Mar 2005
    Posts
    2
    This is for the Seattle area.

  4. #4
    Join Date
    Jul 2004
    Posts
    322
    "Two-stage" and "variable speed" are somewhat confusing terms and are not mutually exclusive. Variable speed usually refers to the blower, while two-stage sometimes refers to the gas valve which can burn gas at a low or high stage. So you can have a two-stage variable speed furnace. If you also have AC you can have a two-stage compressor as well.

  5. #5
    Join Date
    Jan 2005
    Location
    Seattle
    Posts
    191

    Wink To be Variable or not to Variable

    terry26.I live in your area.I don't know how much you understand about this stuff.You said what you were going to buy a given furnace than asked what it was.
    I can tell you for a fact that you want the two stage furnace.That is in referance to the gas valve.The variable speed part that people talk about is in referance to the blower motor.That the blower(fan) that moves all the air around your house.If you are going to also have a electronic air filter installed so that you can filter the air in your home 24/7/365 than you want the variable blower.This is because of the energy savings provided by this type of motor.If you are installing air conditioning
    than you want the variable motor.This is because of the ability of the motor to"wind"down during the cooling cycle.This helps alot with the removl of humidity.There are more reasons to be variable or not to be variable but if you answer to these first two questions is no then you have no need for the variable speed blower motor.As far as your question about which efficiency you want 80% or 90%.You need to look at your present natural gas consumption.Also what kind of efficiency your present furnace is.With that information you can ballpark your saving with the 90% furnace fairly easily.There are alot more accurate ways to calculate the savings but that the easest way.Other considerations for a 90% over a 80%.Noise the 90% furnaces have a enclosed combustion chamber.They are a LOT quiter than a 80%.So if the location of the furnace is in the
    house.do you have to turn up the tv when the furnace comes on?How long are you going to be in your present home?Meaning are you going to be there long enough to recover the investment of the 90%? Something else to consider that most of the heating and a/c companys don't seems to bring up.Have you considered a heatpump?If you spend the time to calculate you energy use to heat you home(btu's) than you can look at how much you pay for which kind.Electic,LP,Natural Gas,Wood.One thing in this regard, that I considered.Was what fuel prices I thought were going to remain the most stable.The anwser in the Seattle area is electricity.One of the benefits of a heat pump is the air conditioning.
    41GASMAN




  6. #6
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Originally posted by Toolpusher
    You didn't put where you live in your profile,
    So no-one here can say whats best for you.

    Depending on your climate, an 80% may well be all you need.
    An 80% 2 stage will save on gas consumption, a variable speed will save on electrical consumption, and give slightly more comfort if the ductwork is correct.
    Actuly, two stage gas heat doesn't cost less to operate. Half the gas for twice the run time. But it does make for more even and comfortable living and are typicaly higher end units. This means they are built a bit better and quieter.

  7. #7
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    I also agree with gasman, a heatpump is a great energy saving way to heat and cool your home.

  8. #8
    Join Date
    Feb 2003
    Posts
    275
    why not use duel fuel? Heat pump for first stage and gas for 2nd, no upgrade needed in the box to accomidate heat pump

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