Heat Pumps - should I buy one for my house?

Discussion in 'Community Discussion' started by maflynn, Aug 20, 2013.

  1. maflynn Moderator

    maflynn

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    #1
    I think I already know the answer to this question but I'm posting here to get other opinions and whether I missed anything in my analysis.

    I recently had an energy audit done to my house, which they said I needed to improve the insulation, use better light bulbs etc, etc. They also mentioned the use of a heat pump to save on my heating bill. The energy audit company is a non profit company that the utilities certify and sanction so they can decrease energy usage.

    After having the guy come in and present what he had to offer I'm trying to see why I'd want to do it.

    They recommended installing a heat pump for upstairs that will heat the second floor in the winter, and cool in the summer. This will reduce my gas usage (natural gas is used to heat my house) by about 20 maybe 30% Additionally I'll save about 20 dollars a month on my electric bill in the summer.

    Putting it all together, I'll save about 500 to 700 dollars a year (I think the upper end is a bit too optimistic). The cost of this is 8,000 (installed). Running the numbers, it will take over 10 years of usage before the unit pays for itself.

    If I finance it (the utilities are sponsoring a 7 year no interest loan) means I'll be paying 100 dollars a month to reduce my gas/electric bill by 50 dollars - that doesn't make sense to me.

    So long story short, since there's no financial incentive for me, are there other advantages to the heat pump that I'm not thinking of?

    I'm not looking to be convinced to get it, or justify my spending of the money but rather I want to cover my bases as I think this through.
     
  2. jwjsr macrumors 6502

    jwjsr

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    #2
    I was recently quoted 3k for 3 1/2 ton heat pump 14 seer split unit installed
     
  3. eawmp1 macrumors 601

    eawmp1

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    #3
    Any tax credits offered for doing this at the state or federal level you've not factored in? Also some utilities offer rebates that could alter the equation.

    And do not forget the potential comfort intangible.
     
  4. maflynn thread starter Moderator

    maflynn

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    #4
    There are cheaper units but we needed an 18k BTU unit (not sure how that translates into tons) with two wall mounted units. I also need an electrician to add a subpanel to my breaker box because what I have is filled up.

    I think living in the northeast where temps can get rather cold in the winter we need a unit that performs fairly well until you get into the 5f degree range.


    I'm looking at about 300 dollars in tax credits and another 300 to 400 in mail in rebates. Total cost should bring be down closer to the 7k mark.

    I agree the comfort and quality of life is a factor, including the absence of needing a window a/c unit in the future.
     
  5. Shrink macrumors G3

    Shrink

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    #5
    I can only speak from personal experience, not from any technical expertise.

    I had an office in a building using a heat pump. It was fine for fairly mild weather heating and cooling needs. However, when the temps went outside a fairly narrow range of temps, the heat pump was not effective...especially in hot weather. If the temps went into the teens (or lower), or into the high 80s, (or warmer), the heat pump couldn't really keep up, and the temps indoors frequently became uncomfortably hot or cold.

    It was my understanding that the heat pump is fine for climates with fairly mild small temp range, but for the significant temp range of New England it is not really effective.
     
  6. jwjsr macrumors 6502

    jwjsr

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    #6
    Do you also have to install ductwork. The a/c man was trying to sell me the cheaper goodman brand by pointing out that all the manufacturers now use scroll compressors now and offer the same 10 year warranty. How many square ft is your upstairs?
     
  7. maflynn thread starter Moderator

    maflynn

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    #7
    Good point - I was aware that heat pumps don't work too well in extreme cold, but I did not consider the upper range of the summer. We were dealing with a significant heat wave in July here in Boston. I'd want a cooling unit to keep the bedrooms cool when the outside temps reach the mid to high 90s as they can occur during the summer here.
     
  8. jwjsr macrumors 6502

    jwjsr

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  9. maflynn thread starter Moderator

    maflynn

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    #9
    No ductwork installed (I have forced hot water heating). I don't have the square footage handy as I'm now at work but he was looking to put in a 12k BTU unit in my bedroom and another 7k BTU unit in the other room to cool the rest of the 2nd floor with a compressor sized at 18k BTU (I'd question by the two wall units exceed the compressor size).
     
  10. jwjsr macrumors 6502

    jwjsr

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    #10
    Think we are talking about 2 different animals, mine requires ductwork.
     
  11. maflynn thread starter Moderator

    maflynn

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  12. Shrink, Aug 20, 2013
    Last edited: Aug 20, 2013

    Shrink macrumors G3

    Shrink

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    #12
    I, unfortunately, know all about this summer's heat wave...I live about 20 miles South of Boston!:eek:

    And my electricity bill went to double my average because the the A/C usage.:(

    BTW: I would suggest that the heat pump's most noticeable weakness is on the A/C side.
     
  13. jwjsr macrumors 6502

    jwjsr

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    #13
  14. jasonvp macrumors 6502a

    jasonvp

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    #14
    Your challenge is: heat rises. The gas you're using to heat your home is going to continue to be "spent" warming up the lower floor, regardless of whether you have a heat source upstairs or not. The only thing the upstairs heat source is going to do is make it a bit more comfortable there.

    I don't know the layout of your home, but it's possible that the two heat sources will be able to create a thermal equilibrium, thereby allowing the gas furnace downstairs to shut itself off. But that's highly unlikely.

    Some things to bear in mind:
    • As mentioned: you'll need to separate the ducting somehow. That's gonna cost ya, and may involve digging into the walls. Again, I dunno the layout of your home.
    • Air source heat pumps are insanely inefficient above the Mason-Dixon line as a heat source. Once the ambient temps get too far below 40ºF or so, they really can't do much to heat the air. Along with the heat pump, they'll install resistance heat as an "emergency". Beware: that'll send your electric bill into the stratosphere if it kicks in a lot.
    • Love it or hate it, natural gas isn't as efficient a heat source as other petroleum sources. The great thing about it is that it's plentiful and fricken cheap.

    Here in the south, it's not uncommon for homes to have 2 heat pumps (ie, dual zone) because it doesn't usually get as chilly here as it does up north. They're still not that efficient here; folks prefer to use natural gas where available and continue using the heat pumps purely for cooling.
     
  15. prostuff1 macrumors 65816

    prostuff1

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    #15
    Heat pumps are not worth it in cold climates.

    I live in the Columbus Ohio area and once it gets to about 35F outside my heat pump hits a magical cliff where efficiency drops off pretty good. My heat pump is not the newest but if I could replace it with a furnace and separate AC I would in a heartbeat. If the heat pump itself can do a good job at heating then the "coil" (resistant heating) will kick in to help and then your electric bill will climb quickly.

    My street does not have the ability to get natural but I am on a corner lot next to a street that does have natural gas access. When I get the time and money my heat pump, electric water heater, and electric stove will be replaced with a NG furnace, NG tankless water heater, proper AC unit, and a gas stove.

    I bought my house 3 years ago and after the first winter trying to use the heat pump I gave up. I use a wood burning insert in my fireplace and burn wood all winter long. Cost me about $100 in gas and chainsaw stuff to get all the wood I need to burn for a winter. WAY cheaper than anything else.


    I guess what I am saying, is that I would not invest in the heat pump right now. Do the insulation and the like and go from there. Most Electric companies are giving some sort of rebate for doing that. I know I bought about $800 worth of blown-in insulation, did it myself and then got a $200 rebate from my electric company.
     
  16. maflynn thread starter Moderator

    maflynn

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    #16
    Thanks for the information guys.

    Just finished a conversation with the wife and we decided to wait on this. There are other things we can do to our house that will have a better bang for our buck.

    There are some advantages but given the extremes in temperatures we experience here in Boston (single digits in the winter up to upper 90s in the summer) and the projected savings is less then what we'll be paying out. Its best to skip this home improvement project.

    I will be looking to add more insulation to our attack and cellar, which will decrease our heating needs, and we already put in smart thermostats (thanks to the Mass Save energy audit) so that will help as well.
     
  17. Huntn macrumors G5

    Huntn

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    #17
    There are many factors all with cost and computed long term payback, which may or may not be overly optimistic. Besides having a decent furnace and windows, I believe the single most bang for the buck you spend is to get R50 in your attic. When we moved to Texas, the house had minimal attic insulation. $2400 to put in 2' of cellulose has made a huge difference in our energy bills.
     
  18. 4JNA macrumors 68000

    4JNA

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    #18
    dump the pump.

    live south of Chicago a bit, looked into this last year, and came to the same conclusion. did reverse analysis on the previous couple years, and the numbers just don't add up. we went the insulation/windows route, added a nest thermostat (highly recommend!), and now just installed a new front door. energy use is down over 50%, house is way more comfortable, and temp swings are way down over what the were prior the the upgrades. money outlay was about even (upgrades over new heatpump/acc/install). cheap and comfortable for the win. :)

    YMMV. best of luck.
     
  19. Tomorrow macrumors 604

    Tomorrow

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    #19
    Unless somebody is telling you to get a heat pump that is more efficient than your current air conditioner, you're getting some incorrect information here. Generally speaking, a heat pump is no more or less efficient at cooling than an air conditioner. It's all about SEER rating; if those are the same, then the efficiencies are the same.

    The only real difference is in heating. You can most certainly see some energy savings, depending on your house and how you use your heat.

    Consider this - a heat pump does not convert electrical energy into mechanical energy (like a conventional electric resistance heater), and it doesn't convert chemical energy into mechanical energy (by burning a fuel); it transfers heat mechanically from one source to another, in this case from outside to inside.

    This gives an efficiency of 100% for electric heat, 80% or so for gas, and around 300% for a heat pump. So yes, a heat pump is more efficient for heating.

    The downside is that, as you pointed out, the efficiency of a heat pump decreases as the temperature outside decreases; and once the temperature outside begins to dip below around 40 degrees, the heat pump becomes largely ineffective, and you're better off turning on the "emergency heat" cycle, which is typically either electric or gas.

    Back to my point - depending on your house, and how you heat it (how warm you like it, etc.), the heat pump may or may not work well for you. In my case, by the time it gets cold enough outside for me to want to turn the heat on, it's too cold for a heat pump to do me a lot of good. My wife, however, feels differently. :eek:

    1 ton of refrigeration = 12,000 Btuh; the unit you needed would be 1 1/2 tons, nominally.

    If you were having trouble cooling you most likely had either a faulty system or an undersized system; this could mean the unit itself, or the ductwork, or the air distribution, etc. Again, there's no difference between a heat pump in a cooling cycle and a conventional air conditioner.
     
  20. monokakata macrumors 68000

    monokakata

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    #20
    If you said anything about your furnace (current) I missed it. I think you said you've got a hot water system.

    I have a 19th century farmhouse in a cold, snowy part of Western NY (south of Buffalo). It's very well-insulated with high-efficiency windows and storms all around (I ripped much of it apart during renovations) but one huge difference has been a smart high-efficiency boiler. I have hot water heating. This gas boiler (Triangle Tube) has an outside sensor in addition to the usual interior thermostats, and is capable of running its burner at partial levels (as opposed to fully blasting or off).

    It computes the delta between outside temp and desired inside temp and that tells it how hard to crank the burner.

    Here's my bottom line (which I know because I've got the house on the market and buyers want the information) -- for the 12 months ending in May 2013, my total gas plus electricity bills averaged about $175/month, combined. We typically keep the house at 68, and much less at night, so of course that helps, and have a lot of CF bulbs in place.

    But the furnace is a wonder. True, it cost something like $6,000, and I'm leaving before it's paid for itself.

    Insulation plus high-quality high-efficiency furnace -- doesn't do anything for cooling (although the insulation helps) but as for heating -- it's very nice.
     
  21. hallux macrumors 68020

    hallux

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    #21
    The panel is full? Have you had an electrician assess things? You may need to upgrade to a higher amp service to support the additional load, my parents did when they had A/C installed.
     
  22. designs216 macrumors 65816

    designs216

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    #22
    We have a dual fuel system that gives the best of both worlds for cold weather but I consider the heat pump to be the Achilles heal during our sweltering, humid NC summers. If I were to make an improvement, I'd first redo the insulation, which would improve both cold and hot weather comfort.
     
  23. jwjsr macrumors 6502

    jwjsr

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    #23
    My 20 yr old heat pump is not "Achilles heal", and I live in the Deep South
     

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