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Community and Q&A

Heat-pump water heater in Canada?

threehappypenguins | Posted in Energy Efficiency and Durability on

I live in Nova Scotia in zone 6B. We’re thinking of installing a heat pump hot water heater (my husband would do it himself) and not sure of how efficient it would be. We just bought the house, and the inspector told us (he used an infrared camera) that the house is well insulated. It was a Kent Home built in 1986; a split entry. We are going to have someone install a mini-split ductless heat pump in the living room upstairs. The rest of the house is heated by baseboard heaters. We pay 14.8 cents per kwh (no time of day billing). There are 5 of us (me, my husband, 6-year-old, 4-year-old and a 3-month-old baby), and I stay at home with the kids (permanently; we homeschool). It’s also very humid here, especially during the summer. We have times with 100% humidity.

No matter what, we need to replace the hot water tank, because it’s as old as the house.

Would it be a good idea to install? Would it save us a lot of money, even during the winter?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Sarah,
    There are limitations on where a heat-pump water heater can be installed: you need a big room, not a small room, that is warm during the winter, but not too close to your bedroom (because these units are noisy).

    In cold climates, these units are usually installed in a basement. This will work, as long as your basement doesn't have a low ceiling.

    Here is a link to an article with more information: Heat-Pump Water Heaters Come of Age.

  2. threehappypenguins | | #2

    It would be installed in an open, uninsulated basement. We plan on insulating and creating a separated laundry room where the hwt would be. It's not a huge room, but not small either. The basement also has baseboard heaters. My son's room will be in the basement. The room is partially finished (and is also insulated). If the noise is the same as a dehumidifier, then it doesn't bother us any. We have to have a dehumidifier running 24/7 in our climate. We all sleep with noise machines (white noise) anyway as well.

    No low ceiling in the basement either.

  3. user-4053553 | | #3

    I'm not sure which model of ductless would work best in your climate, but having partial minisplit and partial still on baseboard is not going to net the maximum benefit.
    Also i would get an energy audit done, to get proper load numbers most installers go by rules of thumb instead of doing a CSA F280 calculation (Manual J) and decide on a whole house solution. When they do the blower door test personally track down where all the air entry points is into the house are (with pictures as visual reminders) so you can airseal those areas, which can reduce the house load by 20-40%. Expect areas such as light fixtures, windows, crown molding, floor joists, mudsill, utility chases, attic hatches and so forth.

  4. threehappypenguins | | #4

    What? What other option is there besides minisplit and baseboard heater? I thought you couldn't have a heat pump by itself? That back-up heat is needed? We can't install a duct heat pump because that would be way too much money. We don't even have ducts, or a furnace or anything.

  5. Expert Member
    Dana Dorsett | | #5

    The heat pump water heater will definitely save money, but as Alan points out, not nearly as much if room where the water heater is located is heated with electric baseboard.

    There is no location in NS where it makes sense to leave a basement uninsulated, ESPECIALLY a basement that is heated with baseboards and ~15 cent electricity. Even if the basement is allowed to drop to 10C, when it's -20C outdoors there is a HUGE heat loss through a typical ~R1 poured concrete foundation.

    Prioritize air sealing and insulating the foundation- that will make a bigger difference in electricity use than heat pump water heater vs. cheap electric, but both are cost-effective at your utility rates.

    At 100% humidity you will have fog forming in the air. I sincerely doubt that's happening indoors, even when it's happening outdoors. The more relevant number is the absolute humidity, measured either as dew-point or wet-bulb temperature. There may be times when the outdoor dew points are higher than the slab temperature in the uninsulated basement, but the slab will normally take up most of the humidity from incoming infiltration/ventilation air as adsorb, unless it has a vapor-impermeable flooring, in which case you'd have liquid water forming on the floor. The average mid-summer dew points in say, Kingston NS run about 59F/15C- pull up a dew-point graph and scroll out:

    https://weatherspark.com/#!dashboard;a=Canada/NS/Kings/Kingston

    The deep subsoil temps are probably about 8-10C (roughly your annual mean outdoor temp), so unless the slab is insulated you could end up with mold growing on susceptible things (like rugs) resting on the floor in summer, unless you actively dehumidify the basement to a dew point of about 10C or less. That would be about 53% RH @ 20C, or 46% RH @ 22C.

    If you air seal and insulate the basement the basement will automatically be somewhat drier, but that won't fix the cool slab issue. Putting rugs down would be a mistake, but if you have the head room even 1" of rigid EPS foam with a wooden subfloor on top of the foam would make rugs less mold prone, 2" would even better, and a bit more comfortable in bare feet.

  6. GBA Editor
    Martin Holladay | | #6

    Alan,
    Your comments caused me to scratch my head. Sarah asked a question about a water heater, but your comments seem to discuss space heating and air sealing issues.

  7. user-4053553 | | #7

    The future ductless in the living rm and baseboard for the rest of the house struck me as odd, why not heat pump the entire house, which means knowing its load, which leads to energy audit and air sealing

  8. GBA Editor
    Martin Holladay | | #8

    Sarah,
    You should check the specs on the heat-pump water heater that you are considering, to make sure that the room where the water heater will be installed meets the minimum size (volume) requirements established by the water heater manufacturer.

    I agree with Dana that insulating your basement walls would be a cost-effective investment. It will also improve your comfort. Here is a link to an article on the issue: How to Insulate a Basement Wall.

    While it's true that one side effect of installing a heat-pump water heater in a damp basement is that the operation of the water heater helps dry out the basement, that doesn't mean that choosing a heat-pump water heater is the best way to address a damp basement. Here is a link to an article you may want to read: Fixing a Wet Basement.

  9. threehappypenguins | | #9

    Alan, there is no way we can completely rely on a heat pump for the entire house in our climate. We *have* to have back-up heat. Most of the time, the weather won't get cold enough, but sometimes it does, and the heat pump will be ineffective. We plan on getting a heat pump (the house is only about 1200-1500 sq ft max) that will handle the upstairs. If we completely finish the basement, perhaps we'll get a heat pump down there as well, but not right now. We need the baseboard heaters as back-up.

    Martin, thank-you for that link! We did decide that we're going to get a heat pump hot water tank. Kent is selling AO Smith Voltex 50 gallon ones for $1,799 + HST (which is 15% so that will come to $2,068.85). Our Canadian dollar sucks, so that's the best we can do. We're *definitely* going to insulate the basement. But I know that we use a fair amount of hot water. I try to do cold washes and stuff, but I also cloth diaper (which needs hot washes) because it's wayyyyyyyyy cheaper than disposables. I've asked around and some people have saved $700 a year getting the heat pump hot water tank, even in this climate.

    Again, thanks for the link. I know a lot of people use the pink batts, and it's good to know about the mold problem with them in the basement. The partially finished room in the basement has the pink batts in it. I know because they cut a small hole in the drywall in order to fish a coaxial cable through (why they did it after they put a wall in a partially finished room is beyond me). And in that hole, I can see the pink batts, and... there is mould on them. :S

    So that explains why!!! We'll have to tear down that outer wall, rip out all the pink stuff and start over. Boo-urns. I sent all that info to my husband. It's hard because the place that he works at has all kinds of "weekend warriors" and they're all like, "Do it this way. You don't need to do it that expensive way. That's just over-the-top," etc. But my husband is pretty level-headed and wants things done right. So we make sure to do our homework first and not just take word-of-mouth.

  10. user-4053553 | | #10

    I believe some heat pumps have electric resistance backup built in to them, but i am not an expert on them by any stretch, so take this with a grain of salt, but i would size it for the entire house (if cost effective, crunch the numbers), and leave your current baseboards for the rare days you might need them since they are already installed, but treat them as a backup, only used if the heat pump is overwhelmed. I have no idea what your design temp is or if there are minisplit models that work that low, but this article explains the design temperature
    https://www.greenbuildingadvisor.com/blogs/dept/building-science/we-are-99-and-1
    If i understand correctly your plan is heat pump water heater, baseboard heat near it, and upstairs heat pump. At minimum i suggest heat pump water tank, heat pump nearby and baseboard upstairs (further away) so that the highest two loads are being handled by heat pumps instead of one pump being fed directly by resistance.

  11. threehappypenguins | | #11

    As far as my understanding, only the whole house heat pump (forced air; like a furnace) have electric resistance built in them for back-up. The minisplits do not. And it's not practical (the payback won't be enough) to install ducts and have a heat pump furnace for the whole house. It would cost about $15,000 or so.

  12. T_Barker | | #12

    I think installing a heat pump hot water heater is a mistake in any heating dominated climate, and marginal anywhere else for that matter.

    If you calculate the energy (hot water) created by the unit, then calculate the energy (cool air) introduced by the heat pump into the localized air, it is basically a wash. In other words, the amount of hot water energy you get from the heater is about the same as the cold air energy (and subsequent additional heating load) you dump into the room. There are studies that demonstrate this.

    So it really comes down to the cost of each of your energy sources. If you are creating hot water with electric power and also heating with electric power then you gain absolutely nothing (same per unit cost). Granted, a mini split air source heat pump will be more effective than electric baseboards, but still... And if you are heating with some sort of natural gas source that is typically much lower per unit cost than electricity, then that heating energy will be at a lower cost, so yes you will gain some savings.

    But when you consider the noise issues, and the localized air comfort issues these water heaters introduce, they make absolutely no sense to me.

  13. Expert Member
    Michael Maines | | #13

    PracticalGreen, the actual math is pretty difficult, because of all the changing variables--even the PHPP has trouble getting it accurate. But in general the consensus is that although heat pump water heaters use heat you have already paid to condition, they still come out way ahead on energy savings. https://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/heat-pump-water-heaters-cold-climates.

    As for noise and comfort, I agree with you there. One solution that addresses all of these concerns is the Sanden split unit water heater. Unfortunately the cost does not make it a good financial investment, from what I have found, but that's not always the deciding factor.

  14. Andrew_C | | #14

    If the goals are saving money and improving comfort, and avoiding mold, I would probably start with a real energy audit that includes a blower door test. Infrared cameras used without blower doors can spot missing insulation, but they won't see air leaks as well, and that's often a significant factor.
    Insulating the basement will help with energy costs, but will really make a difference in comfort and reducing the potential for mold throughout the house. Especially if someone is going to be living down there, I'd give serious consideration to basement insulation.
    Also, if you're always at home, and living in the basement, I'd check for radon and consider putting in abatement measures prior to any other work on the basement floor.

    Sorry that this doesn't address your water heater question. For our usage and energy costs, I decided to get a cheap water heater that cost 1/3 as much as many other options. And getting one that was silent (electric) was a HUGE difference compared with the old power-vented one. Once you're aware of a particular noise, it'll grind on you. IMO, I'd avoid a noisy solution to your hot water.

  15. calum_wilde | | #15

    Hi Sarah,

    Fellow bluenoser here. I'm in Middle Sackville, about half way into the Mount Uniake snow belt and one of the colder parts of the province. We have Fujitsu extreme cold mini splits on both floors of our Kent home split entry... Aside from our insulated basement your story seems very similar to ours. We also have baseboard electric as a back up.

    A few points to consider, we haven't turned on our backup heat yet this year. That very cold week at the end of December was getting close to the end of the heat pump's abilities, but we were still doing fine. Whole house ducted heat pumps don't seem to be caught up with ductless technology, as far as I know, and still require backup heat to be used in our climate. But the smaller and more efficient ductless units are fine here if they're well matched to your heating loads.

    Our power rate here, as of January, is $0.15331/kWh plus an additional 5% federal tax for a resulting ~$0.161/kWh.

    With your present setup of electric baseboards heating in your basement I really doubt you'll see significant gains from a heat pump water heat. You'll still be heating your water with electric resistant heat, but with the added inefficiency of heating the basement first, then taking the heat from the air and moving it into the hot water tank. The summer would see an improvement, and you hopefully wouldn't need the dehumidifier, but I still doubt the gains would be worth the price. If I were you I'd consider a simple electric water heater, with an R10 blanket, some rigid foam insulation with plywood or OSB on top to insulate it from the concrete, and some low flow shower heads. On top of that use the eco setting on your dishwasher and cold water for laundry. There's not much you can do for the kids baths but those measures would likely give similar if not better gains than the heat pump water heater, in our climate. If you switch to heat pumps for your heating the story might be different, but I'm not sure if the difference would be enough to actually be worth the price.

    Look for Frost King SP57/11C Water Heater Blanket and Niagara Earth on amazon for the products that we're using and I have no problem recommending. Also, if you're in the metro area, check out Ground Hog geothermal for your heat pumps. I had several word of mouth recommendations for them before we decided on an installer and the recommendations there were all spot on.

    As for the rest, the air sealing, insulating, etc. I agree that those would be much more beneficial, but the price can be daunting. I would check out Efficiency Nova Scotia, they offer many rebates that would benefit you guys, especially $100 home energy audits.

    Have you even found a retail distributor of heat pump water heaters here? I've looked as we're a lot further down the line of home efficiency to the point where it might be our next logical step, but I couldn't find any.

  16. threehappypenguins | | #16

    Calum, thanks for your reply! What ended up happening (my original question was from 2 years ago), is we found an AO Smith Hybrid Hot Water Heater at Kent. It came to $2,000 after tax and my husband and a friend installed it themselves. Sunshine Renewables also installs the same ones, but it's $3,000 after the installation... so... no, lol. However, Kent no longer sells it. I have no idea where in the province to get one at this point.

    It has some nice features, such as vacation mode. I can set it to how many days we'll be gone, and it will go into a kind of dormancy, then come back when we get home. I usually leave it in hybrid mode, where it will use the heat pump, but if it's inefficient or needs to heat the water faster (say we use a lot), the electric portion will kick in.

    It's hard to tell whether it saves us money. Our bill certainly goes wayyyyy down in the summer, and wayyyy up during the winter. I'm convinced that our basement is simply too cold. Our original plans were to finish the basement and put in another heat pump, but honestly, I think we're just going to install a wood stove in the basement instead for now. Our bill in the winter is outrageous. Like, December and January was over $900. A wood stove is good because wood is fairly cheap (compared to electric), and we will also be able to heat the house if the power goes out (and we all know Nova Scotia Power is UNRELIABLE).

    We will see how efficiently the water tank runs if the basement is a bit warmer through the winter. My husband is in the midst of building a bedroom down there, and once that's done and my son moves in it, we will focus on the rec room where we plan to put the wood stove.

  17. calum_wilde | | #17

    Sarah,

    Is that $900 for two months?? I sure hope so. NS Power has equalized billing so you pay the same month to month. But even still our power bills are only about $1850 for the year.

  18. Expert Member
    Dana Dorsett | | #18

    At the stated ~15 cents/kwh $900 comes to 6000 kwh, which is about 20 million BTU (MMBTU), or 200 therms. Heating with baseboard at 100% efficiency that would not be an unusual monthly bill for an otherwise reasonably insulated 1200-1500' framed house in NS that has NO FOUNDATION INSULATION.

    A cold climate mini-split covering at least most of the load could cut that in half.

    The uninsulated basement could be as much as a third of the whole heating bill (even if it's not being heated directly) but it's more likely to be less than 1/4. Once insulated it becomes a single-digit percentage of the total heat loss, despite the fact that it will be considerably warmer post-insulation.

    A woodstove in the basement can be problematic, more prone to backdrafting than putting in in an above-grade location, since the air-intake to the house would usually be higher than the firebox. The heat loads of insulated basements are also quite small, and it's likely that a wood stove in the basement can't be fired at a rate high enough to keep it's emissions levels in check without overheating the basement.

  19. threehappypenguins | | #19

    Calum Wilde, yes, that is for 2 months. We do have equalized billing, and we pay $300 a month on average.

    Dana Dorsett, we qualified for the Home Warming Program in Nova Scotia, and they installed an HRV (and WHAT A DIFFERENCE! Our windows are no longer soaking wet in the winter) and they spray foamed most of the walls in the basement below grade. We are planning on finishing the basement (with the exception of the laundry room and storage utility room) where we are going to use Dricore R+ to insulate the floor under the laminate.

    The other reason we want a wood stove is because Nova Scotia Power is crappy. There's nothing like having the power go out in the winter, only to have to crack the window, set up our CO detector, and run a propane heater to keep our family warm. A wood stove would solve that pretty easily.

  20. Expert Member
    Dana Dorsett | | #20

    A wood stove with the fire box below grade would always require a CO detector. With the fire-box below grade wood stoves are far more prone to backdrafting than if installed above grade. In a house as tight as yours it would also almost always require cracking a window when cold-starting it.

    If installed somewhere other than the basement, a wood stove with combustion air piped directly to the firebox, with the air intake on the exterior wall no higher than the firebox the backdrafting issue is substantially mitigated, but never completely. Wind pressures can still cause it to backdraft, and use of a CO detector is still prudent.

  21. threehappypenguins | | #21

    If I have any kind of burning appliance (gas stove or hot water heater, oil furnace, wood stove no matter the location, etc), I would definitely have a CO detector. I think it would be stupid not to have one. We actually own one, anyway, because we used to rent a house that had an oil furnace. One time, one of our old detectors malfunctioned and started going off. Of course, we called the fire department because we didn't know it to be a malfunction, and our landlady had a hissy fit (she lived next door). She started accusing us of not "trusting" her (because she got yearly inspections of the furnace). So like I said, CO detectors are always a must. I don't want my entire family dead because of a silent, odourless killer lurking in our home.

  22. cdesmazes | | #22

    Why do we just not put in ducting to the outside for both intake and exhaust air? Add a directional damper to be able to choose for using air from outside or inside or exhaust? I am in Victoria, BC. Who can do this here? Seems simple to me. With air ducting I would not be cannabilizing heat from the house.

    1. ReneeStephen | | #23

      Check out this article on GBA about that: https://www.greenbuildingadvisor.com/article/where-does-the-heat-pump-water-heater-go but yes, it seems that ducting the exhaust air to the outside in cold climates is what the manufacturers recommend. However, makeup air has to come from somewhere (you want the air the heat pump uses to be as warm as possible, ideally NOT from outside.) So if supply isn't ducted, it'll still come in from outside in other ways. So the calculation gets a bit fun.

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