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Thread: Heat Pump efficiency and low temps 2021 - Replacement existing system

  1. #1
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    Confused Heat Pump efficiency and low temps 2021 - Replacement existing system

    So I am working on buying a house with a 3 ton Heat Pump built in 97 with an addition in 2005/6?. Insulation level are mixed 2x6 and 2x4 framing. Not sure on insulation status. We will be redoing exterior and adding 1-2 inch of foam with updated air sealing from the exterior. We will probably replace the windows as well.
    We are also converting a 24x24 garage into living space. 1972 sqft. before conversion.
    We tend to drop the temperature in the house to about 63/64 in the winter as we go to bed. Makes for a better/deeper sleep and raise the temp to 67-69@7AM.
    During the summer we drop the temp at night to the same 63/64 and let it naturally warm up to 72.
    We are in South West Idaho by Twin Falls.

    Heat Pump installed is a Bryant 661CJ036-E and FC4DNF036 installed when addition was done.

    What do you guys advise? Should I replace the Heat Pump with a modern 4ton or leave it? Ground based heat pump?

    Long term I would like to add solar and a wind mill. Heating and cooling = 31% of the average electric bill. Reducing that reduces our solar requirements.

    Thanks for any advice. If there are any additional questions you have feel free to ask.

  2. #2
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    Thread Starter
    I forgot to mention ceilings are average R-38-40.

  3. #3
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    I wanted to find out if it was possible to install solar and a wind mill

  4. #4
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    Thread Starter
    Yes it is.

  5. #5
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    We tend to drop the temperature in the house to about 63/64 in the winter as we go to bed. Makes for a better/deeper sleep and raise the temp to 67-69@7AM

    Reading it you have a Air Handler ? with or without electric heaters? If you have electric heat elements, thinking your somewhat defeating the purpose of saving as your heater element will come on when it goes from 63 to 68, unless you have dirt cheap electric rates and don’t care?

  6. #6
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    Quote Originally Posted by Bazooka Joe View Post
    We tend to drop the temperature in the house to about 63/64 in the winter as we go to bed. Makes for a better/deeper sleep and raise the temp to 67-69@7AM
    I agree, this is the optimal temperature for sleeping!

  7. #7
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    Quote Originally Posted by ngarry243 View Post
    I agree, this is the optimal temperature for sleeping!
    I was asking if you set it back to 63 at night, then raise it to 68 in the morning isn’t your electric backup heat going to come on ( provided you have electric heat in the Air Handler ) if you have electric heat is it expensive to run doing that?

  8. #8
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    Jul 2021
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    Quote Originally Posted by Veev View Post
    So I am working on buying a house with a 3 ton Heat Pump built in 97 with an addition in 2005/6?. Insulation level are mixed 2x6 and 2x4 framing. Not sure on insulation status. We will be redoing exterior and adding 1-2 inch of foam with updated air sealing from the exterior. We will probably replace the windows as well.
    We are also converting a 24x24 garage into living space. 1972 sqft. before conversion.
    We tend to drop the temperature in the house to about 63/64 in the winter as we go to bed. Makes for a better/deeper sleep and raise the temp to 67-69@7AM.
    During the summer we drop the temp at night to the same 63/64 and let it naturally warm up to 72.
    We are in South West Idaho by Twin Falls.

    Heat Pump installed is a Bryant 661CJ036-E and FC4DNF036 installed when addition was done.

    What do you guys advise? Should I replace the Heat Pump with a modern 4ton or leave it? Ground based heat pump?

    Long term I would like to add solar and a wind mill. Heating and cooling = 31% of the average electric bill. Reducing that reduces our solar requirements.

    Thanks for any advice. If there are any additional questions you have feel free to ask.

    Whereabouts are you located? Some states like NY are pushing really hard on cold weather heat pump systems that reduce the need for resistance heating in the winter. There might be good incentive opportunities available to you that may help you afford an upgrade.

    I'm not too familiar with cold weather heat pump technology (yet), but if NYSERDA is pushing it as hard as they are, there's probably something to it.

  9. #9
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    I got a grand in electric company rebates in PA for my HP install.

    I probably would consider replacing the circa 2005 HP just from an age and efficiency standpoint. I have a 2400 sqft house with leaky R15 walls, and R49 attic in central PA. I had a circa 2005 3.5t HP with oil backup and had it all ripped out in 2020 and replaced with a 3 ton Trane XR17, all electric. It has performed great in both heating and cooling seasons.

    The massive heating setpoint swings that the OP suggests will negate most of the savings of insulation and HP efficiency as it will be kicking on the electric elements in the morning.

    The massive cooling setpoint swings will probably create a humidity issue unless it's really that dry of a climate.

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