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  1. #1

    Is heat pump the right choice?

    Hi all,
    My current residence is a 1000sf 1 story ranch home, which is heated with a forced hot air oil furnace. We are planning on adding a second story, essentially doubling the square footage. The second floor will be 3 beds and 2 baths, and the existing first floor will have most of the existing bedroom walls removed to be a mostly open floor plan. We live on the MA/NH border so have cold winters and hot/humid summers.

    I was originally thinking that I would extend the duct work up to the second floor to serve my heating needs, but then started learning about heat pumps. It seems to me that this would be a great choice for me. My plan would be to leave the oil furnace for heating the lower level, and adding the heat pump for heating the second floor (I am thinking that it may not even kick on that often depending on how much of the heat from the first floor makes its way to the 2nd.) Am I on tract here or does somebody have another idea.

    If I am on track here, I had one other question about the heat pump. I would think this unit would be most effectively installed in the attic, from where I would duct into the new second floor bedroom ceilings. Currently the house does not have AC, but now would be the logical time to change that. I am thinking I can run ducts down from the attic to vents in the first floor ceiling. How would this impact the sizing for the unit, seeing that I would only be trying to heat the upper floor but trying to cool the entire house?

    Thanks,
    Jeremiah

  2. #2
    Join Date
    Jan 2012
    Location
    indy
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    471
    Quote Originally Posted by jcojr72 View Post
    Hi all,
    My current residence is a 1000sf 1 story ranch home, which is heated with a forced hot air oil furnace. We are planning on adding a second story, essentially doubling the square footage. The second floor will be 3 beds and 2 baths, and the existing first floor will have most of the existing bedroom walls removed to be a mostly open floor plan. We live on the MA/NH border so have cold winters and hot/humid summers.

    I was originally thinking that I would extend the duct work up to the second floor to serve my heating needs, but then started learning about heat pumps. It seems to me that this would be a great choice for me. My plan would be to leave the oil furnace for heating the lower level, and adding the heat pump for heating the second floor (I am thinking that it may not even kick on that often depending on how much of the heat from the first floor makes its way to the 2nd.) Am I on tract here or does somebody have another idea.

    If I am on track here, I had one other question about the heat pump. I would think this unit would be most effectively installed in the attic, from where I would duct into the new second floor bedroom ceilings. Currently the house does not have AC, but now would be the logical time to change that. I am thinking I can run ducts down from the attic to vents in the first floor ceiling. How would this impact the sizing for the unit, seeing that I would only be trying to heat the upper floor but trying to cool the entire house?

    Thanks,
    Jeremiah
    I would try to put it in a closet if possible, attic units can cause you headaches down the road, not to mention service-ability. The second unit would be the smart choice because the upstairs wont cool right in the summer, most dont, very few do in my exp with only one unit, exp with a fairly large upstairs. You are correct in saying the upstairs heat wont run much in the winter, as for the a/c thats the other way around, so a heat pump would be a good choice upstairs In my opinion

  3. #3
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,665
    I assume you do not have natual gas ,cold winters and mild summers. A heat pump is a good choice in most areas of the us ,could also add a heat pump to the oil burner if the ducts are large enough and insulated

  4. #4
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,582
    Good Choice
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  5. #5
    Thanks for the responses everyone. So am I right in saying that the heat pump will be sized for the larger of the heating and cooling load. In my case, since I am trying to cool the whole house, but only heat 1/2 the house I would expect the cooling load to govern the heat pump size.

    Thanks.

  6. #6
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,275
    Do the math on how much heat loss you will actually get upstairs compared to your electric rates. In Oklahoma it isn't cost effective to get a heat pump or gas furnace for an upstairs install. An air handler with 5KW heat strips is fine since the system only runs when temperatures are really cold. Electricity isn't very expensive here, about 10 cents per KWH.

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,287

    Hmm Heating in NH > Cooling !.!!

    ---------------------------------
    In my case, since I am trying to cool the whole house, but only heat 1/2 the house I would expect the cooling load to govern the heat pump size.
    ----------------------------

    Cooling load is based on Design Temp - Room Temp
    ___Summer 87- 74 = 13'F
    ___Winter __ 0 - 72 = 72'F or somewhere in that range for NH.

    Is it really _intuitive_ that the cooling load is less than the heating load
    ________ when the temperature difference is 6X larger for heating? NOT !

    Cooling load might be ________ ~1 to 1.5 ton for 1,000 square feet, whereas,
    heating load might be ~26,000 BTU/hr +/-30% ( 2.5-ton) for 1,000 square feet in NH.

    You need an inverter based heat pump to compensate for this difference to assure cooling performance is addressed.

    i.e.
    http://www.heynordyne.com/product-innovation/iq-drive
    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

  8. #8
    Join Date
    Jul 2006
    Location
    Virginia
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    4,665
    Quote Originally Posted by 54regcab View Post
    Do the math on how much heat loss you will actually get upstairs compared to your electric rates. In Oklahoma it isn't cost effective to get a heat pump or gas furnace for an upstairs install. An air handler with 5KW heat strips is fine since the system only runs when temperatures are really cold. Electricity isn't very expensive here, about 10 cents per KWH.
    I disagree a heat pump is almost always cost effective over heat strips

  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,287
    Heating Degree Days -5,400
    Cooling Degree Days -_770

    Heating is ~ 7X Cooling

    http://www.wunderground.com/history/...q_statename=NA
    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

  10. #10
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,287
    Quote Originally Posted by catmanacman View Post
    I disagree a heat pump is almost always cost effective over heat strips
    Name just "1 out of a million" [almost never ] case where heat strips would be better than a properly operating heat pump.

    [ lets leave Antartica and Artic Circle /Siberia regions out of the discussion]
    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

  11. #11
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,275
    Quote Originally Posted by dan sw fl View Post
    Name just "1 out of a million" [almost never ] case where heat strips would be better than a properly operating heat pump.

    [ lets leave Antartica and Artic Circle /Siberia regions out of the discussion]
    Just about every install in Oklahoma. Seriously, electric rates in winter are so cheap that a heat pump is hard to justify for an upstairs installation. Electric rates are so low that it's common to use heat strips for the entire house, it's about 50/50 for all electric homes. Yes, HALF of all electric homes use heat strips to heat the entire house!!! I think that's a bit much, a heat pump certainly makes sense for downstairs/whole house installations. http://www.oge.com/Documents/OK/3.00%20R-1.pdf

    If the downstairs is warm the heat rising will keep the upstairs warm for most of the winter, there will only be a few days that the heat would even run. On those days it's cold enough to use upstairs heat the COP of the heat pump is relatively low. Add to that the defrost cycles, additional repair costs and heat pumps just don't make sense with low use situations. 5KW is plenty for most upstairs installs, the heat really is used very rarely. It would take 5+ years in energy savings to pay for the additional cost of the heat pump.

    That all being said in an area where HDD is 7 times CDD and electric rates are higher a heat pump for upstairs might make sense. Just run the numbers is all I'm saying.

  12. #12
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
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    4,275
    Since you currently don't have A/C that tells me it's the upstairs you are most concerned about keeping cool. In Oklahoma the upstairs needs A/C well before the downstairs does. There are many days the solar gain upstairs and heat coming from downstairs are enough to make the upstairs hotter than the outside temperature. Keep the upstairs cool and the downstairs will stay cool on it's own until temps get into the 90's.

    Another idea is run some of the ductwork from upstairs to the downstairs to provide some cooling, and do the opposite for heating. Run some heat ductwork to the upstairs. Temps won't be exactly even, but the only way to do that on a 2 story home is zone or have 2 complete HVAC systems.

  13. #13
    Join Date
    Jan 2009
    Location
    Keokuk, IA
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    5,520
    Intersting idea. Installing a heat pump upstairs and a furnace only downstairs with a small amount of cross over ductwork each way. The only problem is when your cooking or entertaining, the downstairs can get pretty hot. It only work if you have a open concept home with strong convection currents. IF you have a older central hall or foursquare home, convetion currents are often weak. The only movement comes from stack effect and reverse SE. Then again, many homes it that period still just had a gavity furnace on the basement only and only registers wre on the 1st floor. But they often had a chilly upstairs at times. But that's what heavy blankets are for.

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