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Thread: Gas furnace and residential service calc

  1. #1
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    Gas furnace and residential service calc

    Would a gas furnace be included in with "Fastened in place appliances" when doing a service calculation?
    Last edited by jumper; 01-10-18 at 12:00 AM.

  2. #2
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    No.

    It would be counted as the the HVAC load if it were larger than the AC, if AC is larger then it is left out since both do not run at the same time.

    You cannot use it for 220.53

    220.53 Appliance Load — Dwelling Unit(s). It shall be permissible to apply a demand factor of 75 percent to the nameplate rating load of four or more appliances fastened in place, other than electric ranges, clothes dryers, space- heating equipment, or air-conditioning equipment, that are served by the same feeder or service in a one-family, two- family, or multifamily dwelling.
    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #3
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    Quote Originally Posted by jumper View Post
    No.

    It would be counted as the the HVAC load if it were larger than the AC, if AC is larger then it is left out since both do not run at the same time.

    You cannot use it for 220.53

    220.53 Appliance Load — Dwelling Unit(s). It shall be permissible to apply a demand factor of 75 percent to the nameplate rating load of four or more appliances fastened in place, other than electric ranges, clothes dryers, space- heating equipment, or air-conditioning equipment, that are served by the same feeder or service in a one-family, two- family, or multifamily dwelling.
    Jumper
    If you can get your hands on a NEC 2008 Handbook, 220.53, page 120-121.
    They give an example calc and they are listing "Furnace Motor" as an appliance.

    I knew I had seen it, but took awhile to find this.

  4. #4
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    Quote Originally Posted by MyCleveland View Post
    Jumper
    If you can get your hands on a NEC 2008 Handbook, 220.53, page 120-121.
    They give an example calc and they are listing "Furnace Motor" as an appliance.

    I knew I had seen it, but took awhile to find this.
    I have a 2005 and a 2011 HB so I may take a gander, but that really does not change my view.

    Handbook is not code and there has been more than one mistake in the pics and commentary.
    "Electricity is really just organized lightning." George Carlin


    Derek

  5. #5
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    That furnace is an appliance, and if it is a central system that uses same blower to push air through a cooling coil then I'd say the cooling load needs to be the AC unit plus the blower on this furnace, though many generally don't think about adding the furnace blower to the cooling load.

  6. #6
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    Quote Originally Posted by kwired View Post
    That furnace is an appliance, and if it is a central system that uses same blower to push air through a cooling coil then I'd say the cooling load needs to be the AC unit plus the blower on this furnace, though many generally don't think about adding the furnace blower to the cooling load.
    Either way, it cannot be used for 220.53 as an appliance towards the number needed for adjusting a load total using that section.
    "Electricity is really just organized lightning." George Carlin


    Derek

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