1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)

Ductless heat pump, which is a better unit?

Post in 'The Green Room' started by Amaralluis, Oct 8, 2010.

  1. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    I got two guys coming to my place this morning to get me a quote.
    Price is pretty much the same so no real competition there. :(

    They sell two different brands. One is Daikin and the other is Elite.
    Because I am new to this I cant decide which one is a better unit.
    I have a single floor approx 1350SQFt open concept. Really open concept, imagine a box with three walls to create the divisions and the hallway in the middle. That simple.

    I need your expert opinion on which one is the best unit overall between these two:

    Elite

    For the Elite the guy sugested their 12K unit, but Im leaning towards the 18K. Somehow I think 15000Btus is not nearly enough to keep the house warm.
    and

    Daikin


    I appreciate all the input.
    Thanks

    Helpful Sponsor Ads!





  2. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    No opinions?
  3. woodgeek

    woodgeek Minister of Fire

    Joined:
    Jan 27, 2008
    Messages:
    2,798
    Loc:
    SE PA
    I think either unit is fine. The 'Elite' has a 5% lower HSPF, so theoretically it might cost 5% more to run per BTU, but if it were a lot cheaper than the other (on a nom BTU basis) then it might be a good pick.

    Personally, for the cash outlay I would want to have some idea regarding cost of operation/utility/payback relative to your current fuel, etc. IF you buy the wrong size unit, there is a chance you will not be happy/ be wasting money etc. I think you should do a rough heating demand calculation--can you work out BTU/h at something like 0°C? IIRC you had a pellet stove--maybe you know how many kilos of pellets you would use on a day averaging 0°C? If you estimate the BTU/kilo of pellets you get out of a pellet stove (at a nominal eff), you could figure your BTU/hr demand at that temp.

    Compute the price of pellets $$/MMBTU and electric resistance heat $$/MMBTU. The ratio of these numbers is heat pump COP above which it is cheaper to run the HP than burn pellets. If this balance COP is ~1-1.5, then get the biggest HP you can and run it all season. If it is 2-3 then you will want to run it only above 0°C or so, and buy a HP with a max output about 50% bigger than your 0°C demand (to account for the falloff of output at lower temps).

    Can't be more precise without any info RE your energy costs.
  4. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    Woodgeek, thanks for the input I really appreciated but you put me on the spot and I dont know how to calculate btu/h with an average temp of 0. :)

    All I can say is that in the middle of the winter I usually burn a bag a day (with temps around 0C) and more than that as the temp drops further.
    I have an accentra and as far I can remember I have never burn two bags in a day.
    A 40Lbs bag costs $5.99 and hydro is 11cents/kwh

    So in the winter I am burning 6 bucks of pellets per day and that by swinging the temp up when we are home and down when away/sleeping.
    Please educate me on how to calculate Btu/hr?
    The more info I get the better.
    Thanks
  5. DaveH9

    DaveH9 Member

    Joined:
    Jun 11, 2009
    Messages:
    69
    Loc:
    NW CT
    I looked at mini splits. I would go with the highest seer rating. That's looking at the cooling side, I was not interested in the heating. There is a heating side efficiency rating, HSPF, The inverter technology is good, it allows the compressor to run on DC voltage, so it's variable speed. It then can run at the most efficient rate for the conditions. Those min splits have a dehumidification mode, has anyone had any experience with that?
  6. woodgeek

    woodgeek Minister of Fire

    Joined:
    Jan 27, 2008
    Messages:
    2,798
    Loc:
    SE PA
    Rolling up sleeves...

    First, we go to the fuel cost calculator on this site:
    http://hearth.com/econtent/index.php/articles/fuel_cost_comparison_calculator/
    and we put in $300/ton pellets and $0.11 kWh elec, and we get that one million BTUs of delivered heat costs:
    $26.57 using pellets and $32.23 using electric resistance heat (e.g. a cheap electric space heater). First thing,
    your elec is cheap (hydro) and your pellets are expensive. Your pellets ARE cheaper than running a cheap electric
    space heater, but not by much--about 18% (26.57/32.23 = 0.824).

    A Heat Pump will deliver more heat than a space heater using the same elec by its coefficient of performance,
    or COP, that decreases with outside temps. Whenever the COP is >32.23/26.57 = 1.21, the HP is cheaper to run
    than the pellet stove. For the high-eff units you listed, I expect the real COP (assuming proper install, defrost, etc)
    would be >1.5 down to -10°C. Looking up climate tables for your location, it looks like your January ave temps
    are closer to 0°C, so it is likely that a (big enough) HP could heat you cheaper than pellets for nearly all of your
    heating season.

    In this (cheap elec) situation, the usual suggestion is to size the HP to meet your average January demand. Paying
    for a bigger unit to cover those rare super cold days doesn't pay (cuz you rarely use it). Similarly, buying a smaller
    unit will save you less money (by requiring more expensive backup), and the cost of a HP unit goes up more
    slowly than its output capacity (e.g. a unit putting out 50% more BTUs might only cost 30% more to buy up front).

    So now we come back to demand. If a 40lb bag costs $6, and the calculator told us a MMBTU cost $26.57, then
    it takes 4.42 bags to make a MMBTU, or 1 bag is 225 kBTU. If we say you use 1 40lb bag per day in typical January
    weather (0C), then we divide by 24 hours to get about 9500 BTU/hr. So, if you really use about 1 bag/day in typical
    January temps to keep your house comfortable, then you want a HP that puts out that much at your typical January
    outdoor temps. How much do your listed units put out at 0°C I dont know. My slightly lower eff HP (also R410A) puts
    out 46 kBTU/h nominal maximum (at 47F) and output drops to 37 kBTU/h at 32F. If we estimate that your listed units
    are similar, then they would put out about 37/46 or 80% of listed maximum at 0C. In other words, you need a unit
    with an output of 10 kBTU/0.8 = 12,500 nominal max BTU/h to replace 1 bag of pellets/day heat demand.

    Of course, you will have to adjust these numbers--your demand seems kinda low (!), but maybe you have a small, very
    well insulated bungalow that you keep on the cold side. If you really use >1 bag in typical January temps, then you should go
    proportionally bigger than a 12 kBTU/h (nom) unit. As for payback, if you can get a seasonally averaged SCOP of ~2
    (likely for your mild climate) then your average cost per HP BTU is about 40% lower than your pellet costs in this plan
    and your annual savings would be close to 30-40% of your current annual pellet bill. It will likely be more convenient to operate.

    Potential concerns:
    --control. You will have two separate heaters with two thermostats. You will have to set them a couple degrees apart
    so one backs up the other? Not a big deal, but some would consider this a hassle.
    --sizing. We could be wrong and you get a unit that is too small or too big. Too small and you are still running a lot of pellets
    and not saving as much as you could have. Too big and your 'payback' takes a lot longer.
    --future fuel costs: will your elec go up a lot in your payback period? Can you find a cheaper pellet supplier on the internet instead?

    In the end, if your average January temps are really around 0°C (maritime climate), I suspect that you will be quite happy with
    the convenience and $$ savings of a HP relative to pellets.
  7. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    WoodGeek Thank you very much for your explanation.
    Ive learned quite a few things with your post.
    All your assumption seem to be correct on everything, I do use more than a bag a day in the really cold days like -5/-10 but at 0 up one bag is suficient, but like I said I do swing the temps to minimize pellet consumption.
    Did you check the links on my first post, they are for the specs of each unit so you could get all your info out of it.
    The elite has two models the 12k and 18, but as per their specs the 12k outputs 15Kbtus and the 18k 20KBtus while the daikin the unit outputs 21kbtus.
    Pricewise the difference is not that big, the elite 12k installed would cost approx $3200 and the elite 18k and the daikin ftxs15 would cost approx $3700 installed so cost is not the concern.
    My concern with the 12k unit is that it will be running at max power to output the necessary btus with the temps around 0c while the bigger unit will not to need as much power to deliver the same amount of btus? Is this wrong thinking for heat pumps?
  8. woodgeek

    woodgeek Minister of Fire

    Joined:
    Jan 27, 2008
    Messages:
    2,798
    Loc:
    SE PA
    Your concern about the 12k unit running all the time is not a big deal--they are built for continuous operation, starts and stops can actually be harder. Still, I think the installer that rec'ed the 12k unit is making a reasonable assessment (guess?) of your demand and sizing it for 'average' January demand. Basically, I think he is 'checking our math'. As for your question which is better, I would go with the installer I liked better first, and otherwise go with warranty info, what the neighbors are running, etc.

    Personally, I think you will be happier with one of the higher BTU output units for multiple reasons if your goal is to rely on it all season. The lower BTU unit will require more backup from the pellet stove, so you will still be on the hook for tending that and filling it (albeit a lot less) during peak heating season. Moreover, if you do 'setbacks' to save $$, you will like to have a faster recovery when you come home/wake up etc. When the system is near max output, it will probably take too long for your liking. You can always fire up the stove to speed the recovery, but this was about saving pellets. The flip side, is that you might decide to not do setbacks in the future, e.g. someone gets sick/you have visitors that don't like it/etc and then you will need a higher heating capacity overall. If the larger HP handles setback recovery better, you might be more prone to keep doing it and saving money relative to the smaller unit.

    Some other important issues--this system will need to defrost the outdoor coil when it is below about 5°C outside, probably every 30-90 minutes depending on the weather (outdoor humidity). To do this, it will reverse cycle, and pump heat from your house into the outdoor coil until the ice is melted. For this reason, the unit will blow 'cold' air for a couple minutes. (I'm not certain that the units you are looking at do this, perhaps someone who has one can confirm). Another reason for a slightly larger unit is that the output numbers don't account for it running in reverse for 5% of the time, and needing to catch up afterward. My point is that you want to locate the indoor coil in the largest airspace possible, and not direct its airstream directly where you will be sitting (kinda the opposite of a conventional heater). If you were using this for mild weather heating only (>5°C) this would be a non-issue. Some care with siting the indoor coil might make the difference between using it during cold weather and shutting it down b/c you don't like the 'chills'. Talk to your installer here. The outdoor coil siting is also important--it needs to be able to 'breathe', but in a location sheltered from the wind. If it was windswept, then you can get a situation during cold windy weather where it has a hard time defrosting b/c of wind-chill. This will cost you more $$, require more backup and get you bigger cold blasts. Again talk to your installer. Oh yeah, and putting the outdoor unit under a bedroom window is probably a bad idea, due to startup/run noise.

    Note: the installer may be assuming that you will not run it below 0-5°C because of defrost discomfort, and sized the smaller unit for that reason. Moreover, if you decide comfort-wise to not run it below 5°C, then the larger BTU units would be a waste of money. This is an important issue.

    Lest the switching between the two heaters become problematic, ask your installer about options for '2-stage' control. Does the HP have a 'backup call' signal that can energize a backup heater? Does the pellet stove take a compatible thermostat signal input? Can a separate 2-stage thermostat (with setback timer) control both units? Never hurts to ask.
  9. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,038
    Loc:
    South Puget Sound, WA
    The right fit is also going to depend a lot on the house's sealing, insulation, glass exposure and location. Locally we have seen some remarkable results with these units because we rarely get below 20 degrees and then usually for just a short period. Fujitsu makes some good units including their 12,000 btu model which has an great rating of 12 HSPF. At 17°F this unit is still outputting 10K btus, which is quite remarkable. Also popular here are Mitsubishi and Daikin.
  10. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    After much consideration I chose the Daikin and should have it installed soon.
    I hope I made the right decision. :)
  11. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,038
    Loc:
    South Puget Sound, WA
    Between the two, that's the one I would have chosen also. Keep us posted on how it turns out.

    PS: What's the location for this installation?
  12. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    Thanks.

    I live nearby Sussex in New Bruwnswick.
  13. samandlillie

    samandlillie Member

    Joined:
    Oct 2, 2007
    Messages:
    57
    As you already know,I love my Fujitsu as it has already saved me over $1000 in one year. No heat loss up the chimney,no cleaning and purified air to boot.My next door neighbour is an electrician and just installed two 12,000 units himself. The lines and units come precharged with gas. They are UTL units and cost about $1700 each and come from Moncton,NB and are energy star rated.Interestingly, they have a crank case heater and outdoor drain pan heater.Their web address is www.alternativedistributionandsales.com or (A.D.S.) Don,t know enough to recommend them yet.
    Wayne in Nova Scotia
  14. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    Tomorrow is the day... The dealer is coming to install the Daikin.
  15. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    Thats it... Took almost all day but the Daikin is installed and running.
    It sure feels different from my pellet stove, I guess its just a matter of getting used to it.

    Samand how are you using yours? Do you just set a temp and leave it running, or are you using the ON/OFF Timer, or changing temp operation, etc?
    What did you find is the most efficient?
    Thanks
  16. samandlillie

    samandlillie Member

    Joined:
    Oct 2, 2007
    Messages:
    57
    Since the heat pump does not have the capacity of my XXV (18000btu Vs 50000Btu) it takes a lot longer to get up to temperature.I set it and forget it.Also since my inside unit is in an open area, it takes longer. If located in a smaller area,I would do it differently. Hope they put your outside unit well off of the ground, mine was just sitting on a patio stone where there is a higher humidity .
    Wayne in NS
  17. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    49,038
    Loc:
    South Puget Sound, WA
    The output from a convection blower on a pellet stove is going to be much hotter, like 125-135°F, than the heatpump at ~105°F. Let it run and do it's thing. If you set back temps at night, don't lower it too far. Try ~5°F and see how that works.
  18. spirilis

    spirilis Minister of Fire

    Joined:
    Sep 8, 2009
    Messages:
    504
    Loc:
    New Market, MD
    Echoing this, I've found with my central air heat pump (your typical on/off household unit) the use of a programmable thermostat is almost pointless even in the summertime. It takes so long to do anything. Heat pumps are best left to one temperature and left alone IMO. The mini-splits that do variable speed compressor/fan operation are probably left at a single temperature too.
  19. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    Great tips thanks.

    Samand, the outdoor unit is not standing on the ground, It should be high enough that snow wont be a problem.
    I will try to get pics in the weekend.
    I have it set at 20C and the house feels warm which is nice, its currently -1 outside.
  20. samandlillie

    samandlillie Member

    Joined:
    Oct 2, 2007
    Messages:
    57
    Same temp here (Falmouth), my temp. is set at 72 F( made in USA). I have 2 story cape cod so a lot of heat migrates upstairs.My brother loves his Daikin.
    Wayne in NS
  21. Amaralluis

    Amaralluis Member

    Joined:
    Dec 14, 2005
    Messages:
    177
    I was wondering what is the best humidity level to have in the house? By that I mean that makes us feel the warmest? :)
  22. AK13

    AK13 Member

    Joined:
    Oct 15, 2010
    Messages:
    204
    Loc:
    Seacoast, NH
    The higher the humidity the warmer you will feel, but 50% RH at about 70 F would feel nice. In the winter your house is probably more like 30%. But I wouldn't focus on humidifying the space to make it feel warmer. You're better off just turning up the temperature setpoint.

    Also, I agree with the others, don't set back your heat pump more than a couple of degrees, if at all. The pick-up times are slow, plus if you want to come out of setback in the morning you are asking the heat pump to work the hardest when the outside temperature is at its coldest which means lowest efficiency for the heat pump. This likely offsets the energy that you save with night setback.

Share This Page