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  1. #1
    Join Date
    Jul 2005
    Location
    SE PA
    Posts
    183

    Furance gas consumption.....single stage heat vs multistage

    Had a discussion recently with collegues about the consumer's real benefit between a furnace with a single stage gas valve vs a multi-stage or modulating gas valve.

    One school of thought says the net fuel consumption is similar between the furnaces as the multistage will run longer, since it's BTU delivery on low fire is less than the single stage. Thus, the real benefit to a consumer from a multi-stage gas valve is the temperature balance.

    Thoughts on this?

  2. #2
    Join Date
    Aug 2009
    Location
    Little Rock, AR
    Posts
    51
    I agree.

    Therefore, the question is "What price to pay for that comfort?"

  3. #3
    Join Date
    Jan 2009
    Location
    Middle of the Oregon Coast
    Posts
    196
    If the AFUE is the same for both furnaces, no amount of staging or modulating will save your homeowner any money on the gas bill. The only thing that will affect the fuel bill is the efficiency of the furnace. Staging or modulation will make the home more comfortable, though..... better for sitting on the couch drinking beer!

  4. #4
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,904
    A multi-stage furnace can save energy if it allows for a use of a lower setpoint.
    General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"

  5. #5
    Join Date
    Jul 2009
    Location
    Dayton, Ohio
    Posts
    57
    With a multistage or variable blower there will be better humidity control as well. Also, fewer start/stop cycles will result in somewhat longer durability of the unit and a somewhat lower energy consumption due to the fewer warm-up, cool-down fan use. Finally, the variable speed fan uses an ECM motor that would use at least 25% less energy during normal use and far more if the fan is used continuously.

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