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  1. #1
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17

    Should I consider a heat pump?

    Simple question really, or maybe not?

    I live in northern North Dakota. Typical heating season for me is Oct 1 to April 31 with useability of a heat pump being all of Oct and part of March and all of April typically from what I have been able to figure.
    Im looking at having central air installed and all the contractors I have gotten bids from have also given the option of a heat pump for about a 20% price increase. Should i consider it? If you need any further info please let me know. Im just unsure what to do.

    Thanks

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,060
    Price of juice per kwh? Price per therm of gas?

  3. #3
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17
    7.173 per kwh and im on propane which is 1.39 per gal right now

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,880
    As long as your heat pump's COP is above 1.5, it will be cheaper then propane at the rates you posted(I have a .2 fudge in the COP for defrost).
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  5. #5
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    IF your on Propane, absolutely. Actually, a $0.07, it will likely beat natural gas down to at least 35-40F. Personally I like having to fuel flexibility and I'm switching ot dual fuel on one of my furnaces when I replace it. IT also has the benefit of a low stage of heat for comfort.

    You'll still want a high effciency furnace since N Dakota regularly see temps under 30F, so it will still use the furnace quite a bit. With your long winters, you should see a nice savings with a heat pump. A unit with a HSPF of 9, should be above 1.5 COP down to 0F.

    In you climate, you might consider a 2 stage if you have the opportunity to "round up" to the next largest full ton size. Meaning if the load calculation was lets say between 2.1-2.5, you'd put in a 3 ton 2 stage unit rather than na 2.5 ton single stage. Although North Dakota has a fairly extreme climate. Summer design is relatively mild (89-91F depending on location) , but winter is extremely cold... -21 to -18F. I think only northern alaska has a wider range from winter to summer desing temps. Compare that for example to a mid atlantic like Virginia, summer design is simila but less humid, but winter design is almost 2X the heat loss.

    Definitely go with the heat pump. You might also take a look at a split geothermal as wel, still using a propane for aux heat. IF it's a small home, you could also consider a Combi heating soruce with a HE water heater for both domestic hot water and aux hydronic heat. The advantage is that te heat pump can run at the same time as the auxillary, so you use the heat pump all the time all the way down to the economic balance point. Otherwise, it will cycle back and forth between the heat pump and the furnace when it gets under about 25-30F when the heat pump liekly won't keep up. WIth hydronics, or electric heat strips, it will only cycle the aux as needed. A combi boielr isn't a bad option as well, but more expensive. I know a lot of peple had had luck with AO Smoth VOrtex water ehaters in combi applications and Rannai and Navien also allow combi use with their tankless water heaters, but it does shorten their life.

  6. #6
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17
    Well, I just had a big long post I lost somehow so Ill give the short version to explain my situation better,
    I had a new furnace installed 4 years ago. Dumb of me I didnt go with the variable speed unit and wish I had now that I have educated myself further in the last four years about my home. Its a true learning experience. The contractor that installed the furnace also mentioned going with a 3 ton 2 stage unit 16 seer, 9.75 hspf over the 2 1/2 ton 9 hspf he quoted me when I had him out here last week. Nobody here does manual j or anything similar. I had to do it myself 4 years ago and remember rounding down on the a/c and deciding to do 2.5 ton when the cash was available to get a/c. I think it was 2.6. I did have an evaluation done on the house four years ago as well and had a blow door test done at the time and it was 4700 cfm. I got that down to 2300 cfm with a lot of work but cant get it any lower without substantial cost that wouldnt pay for itself in the next 50 years. Heating season is more like -25 with coldest days more like -47. Not much time where its above 20 here in the winter so i want to make sure a heat pump will pay for itself in the life of the unit over just installing a/c. I dont need to have the biggest baddest unit and bragging rights, just a unit that does what I need it to. Im more concerned with humidity in the summer running a 3 ton unit. Is the 3 ton going to be able to cool the house without doing it so fast that it doesnt lower my humidity enough? I assume you are suggesting a two stage unit to cover this situation?

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,880
    If you don't have a VS blower, a 2 stage A/C or heat pump doesn't dehumidify real well in first stage. So rounding up can cause higher humidity even with a 2 stage in that case.
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  8. #8
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17
    Ok so that wont work. Maybe I will see if I can get a package deal and save my current furnace for another project I have coming up. If cost prohibits it tho maybe I could go with a variable unit next year. Or possibly put off the whole deal for now. Wish I had gotten the variable unit to begin with. Been looking at the modulating units online today. They sure seem like a sweet deal. I might look into them further.

  9. #9
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17
    Just an update.
    I went with a 2 1/2 ton heat pump, leaving the furnace I have and just regretting not getting the variable speed but ultimately this system will do the job. Contractor dropped off the unit yesterday in my garage and will return once I get a raised pad installed and all the new wiring ran/hooked up. Doing that work myself as I am qualified and saving a nice amount in doing so.
    It seems I need to install electric heat too for defrost cycle which I hadn't even considered. That unit is in one of the boxes out in the garage but just has a plug in on it for the control wiring and nothing in the furnace or heat pump unit to plug in to so I will have to figure out how to control the unit. I haven't done much control wiring so maybe I will just leave that for the guys that do it every day. Too cold to do any of the work anyways so no big deal I guess.
    I probably jumped the gun getting the unit now when my cooling season doesn't start for another two months but I got a good deal getting in so early.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,880
    is it a package heat pump, or a split system that will use your furnace as the air handler.
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  11. #11
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17
    A split system with my furnace as the air handler.

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,880
    No need for electric resistance heat then. Your gas furnace can provide heat during defrost.
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  13. #13
    Join Date
    Mar 2013
    Location
    North Dakota
    Posts
    17
    I'll leave it be then and point out to the contractor I would like to omit the elec and use the furnace. Less parts, less problems.

    Thanks.

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