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  1. #14
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,273
    Quote Originally Posted by Warlockamized2 View Post
    Only the heat pump will be using it.

    Should I cut the heat-pump off at or near the outside temp that it has to have help from the furnace ?
    YES. mid 20's

    Thermal Balance Point is in the range of 24'F to 28'F
    given the parameters that I have used (attacment)

    Economic balance point is nearly {essentially } the same.

    Demand Defrost operation should be checked.
    Attached Images Attached Images
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  2. #15
    Join Date
    Jan 2013
    Location
    sterling heights Michigan
    Posts
    26
    The outside temp is 14-17 and the heat pump is keeping up without help from the furnace, but its calm winds and sunny. I will watch for the furnace help to heat to set thermostat temp and cut the heat pump off at that point. Will this method also give me the most economical settings? Other parameters come into play , heat pump is on the south side of home, 273 square foot all season sunroom on the south east side of house, attached 2 car garage on north west side of home with insulated door and walls uninsulated ceiling, sealed and insulated band joist, 75 r value on 2nd floor hallway , at least 4 rooms have air sealed electric plug boxes for outside wall plugs.I want to insulate my sealed duct in the basement, but I am not sure what insolation I will use, any suggestions… double foil bubble wrap r11 or spray foam r6 ?

  3. #16
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,273

    Reasonable Cut-Off

    Quote Originally Posted by Warlockamized2 View Post
    I have ordered an electric meter with schedule D1.7 rate, time of day for space conditioning and water heating. I wont be using it for water heating. Only the heat pump will be using it. Should I cut the heat-pump off at or near the outside temp that it has to have help from the furnace ?
    XP 21 C.O.P. is VERY High [ 3.078 ] at 20'F

    Your heat load required at 0'F must be < 40,000 BTU/Hr based on your recent posting
    that XP 21 4-ton can maintain your room temperature ( assume 70'F) at 16'F outside air.

    Economic and thermal balance point must be close to 15'F.

    ATTACHMENT
    I found XP 21 Extended Performance data.
    Second sheet of attachment.

    I would have a heat pump cut-off at 20'F to somewhat minimize operating hours
    and duration/ # of defrost cycles.

    With a 110,00 BTU/HR Furnace, the ON cycle time is going to be Quite Short even at 0'F.
    Attached Images Attached Images
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  4. #17
    Join Date
    Jan 2013
    Location
    sterling heights Michigan
    Posts
    26
    dan sw fi , Can you please find and send me the chart for XP21-48 Heat pump with a CX34-62C cased indoor coil. Please, Please Please. And thank you so very much for the help. My floor has no insolation. Just thick carpet and thick carpet pad. Family room is on a slab.

  5. #18
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,273
    Quote Originally Posted by Warlockamized2 View Post

    dan sw fi , Can you please find and send me the chart for
    XP21-48 Heat pump with a CX34-62C cased indoor coil.

    Please, Please Please.

    And thank you so very much for the help.
    I sent other Lennox info, but got a message your e-mail address was "rejected".
    Check my HVAC-Talk profile for email address and send request.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

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