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How much natural gas does furnace use in one(1) hour??

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  • How much natural gas does furnace use in one(1) hour??

    I posted this on a few other sites and thought I'd share it here.

    I wanted to gauge how much natural gas my furnace consumed after running for an hour's time. An then figure out the cost of that amount of natural gas for that hour. The heating season this year is upon us so thought I'd post this.

    Here are the particlars:
    I have Goodman model GMPN100-4 furnace.
    -natural gas,
    -single stage,
    -pilotless
    -input rating of 100,000 BTU per Hour


    My gas meter has a 2 cubic foot dial. I set a video cam in front of the gas meter in the morning knowing the furnace would be on for at least 20 minutes to bring the house up to temperature from the night's setback. The furnace did run for about 20 minutes but I stopped my readings at 10 minutes. Here are some findings:
    In 5 minutes the furnace consumed 7.6 cubic feet of gas.
    In 10 minutes the furnace consumed 15.2 cubic feet of gas.

    So 15.2 cubic feet of gas in 10 minutes extrapolated out to 60 minutes would be 91.2 cubic feet gas per hour or 0.912 CCF/hr.

    The price I pay for natural gas is $.745 per CCF so the cost for my furnace to run for an hour is about $.68 per hour.


    NOTES:

    1. No other gas consuming appliances(oven, stovetop or hot water heater) were firing at the time of testing.

    2. I understand that outside temp, thermostat setting and how well my home is insulated are factors as to HOW OFTEN the furnace will run. That wasn't my concern. I only wanted to know how much gas was consumed when the furnace ran for an hour. How that hour was achieved was not important. It could of been 60 continuous minutes or six 10-minutes cycles. In my case I took a 10 minute run cycle and multiplied that amount of gas usage by 6.

    3. Figuring one cubic foot of natural gas has 1015 BTUs, 91.2 cubic feet of gas is about 93,000 BTUs which is 7% less than the input rating of the furnace.

    Anything wrong with my data??

  • #2
    Re: How much natural gas does furnace use in one(1) hour??

    7% diffence between a controlled laboratory setting and real world is normal. Gas meters are not an accurate measuring tool.

    Comment


    • #3
      Re: How much natural gas does furnace use in one(1) hour??

      Originally posted by hammerlane View Post
      I have Goodman model GMPN100-4 furnace.
      -natural gas,
      -single stage,
      -pilotless
      -input rating of 100,000 BTU per Hour
      This furnace is known to have major heat exchanger problems. When was the last time it was checked?

      The numbers work fine. It may also be less if the manifold pressure is less than rated or if the meter pressure fluctuates.
      ~~

      ... it was plumbed by Ray Charles and his helper Stevie Wonder

      Comment


      • #4
        Re: How much natural gas does furnace use in one(1) hour??

        Originally posted by plumberscrack View Post
        7% diffence between a controlled laboratory setting and real world is normal. Gas meters are not an accurate measuring tool.
        Correct. I did not expect exactly 100,000 BTU to be used in an hour but a figure relatively close.

        Comment


        • #5
          Re: How much natural gas does furnace use in one(1) hour??

          Originally posted by Plumber Punky View Post
          This furnace is known to have major heat exchanger problems.
          I have not heard of this. Have you serviced many Goodmans for this problem?

          Comment


          • #6
            Re: How much natural gas does furnace use in one(1) hour??

            Many Goodmans, Amanas, and Janitrols. All have the same heat exchanger. They are made of a thinner metal and are prone to stress fractures and delamination. The secondaries are known to crack, leak or plug. The collector boxes and inducer housings are known to crack.
            ~~

            ... it was plumbed by Ray Charles and his helper Stevie Wonder

            Comment

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