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Choosing heat pump water heater

this_page_left_blank | Posted in General Questions on

Just looking for opinions on a couple of heat pump water heater options. Being in Canada, my options are pretty limited, at least if you consider price an object. I’m looking at 80gal models, since I have room for it and the price difference between it and 50 or 65 is negligible.

First, the options I’ve ruled out:

-Sanden SanCo2  The payback period on this exceeds its expected lifespan by a lot, and I couldn’t find any pro willing to quote on it, so I’d have no warranty anyway.
-Steibel Eltron Price point on these just doesn’t make sense to me. They talk up their “not a hybrid” angle, but at the same time their efficiency rating is lower than their hybrid competitors. They don’t seem to have updated their models in at least 5 years.
-AO Smith Voltex HPTU-80N    Price point again, ($3643)

Considered options:

from Home Depot
Rheem PROPH80 T2 RH350 DC (UEF 3.70)   $2704

from local contractor
PROPH80 T2 RH375-30 (UEF 4.00) $3154
Bradford White Aerotherm RE2H80T10 (UEF 3.48)  $2778

All prices include tax and delivery, no install.

The top entry of the Aerotherm is less ideal for my space, but I could work around it. The contractor is pitching me the selling point that he will provide warranty coverage, and that dealing with Home Depot if warranty work is needed will be a nightmare. He might be onto something with that, as I did have a bad experience with a Rheem water heater and Home Depot, although that was many years ago. He also said that the models Home Depot sells aren’t the same ones contractors have access to, and while this appears to be the case in general, it doesn’t appear to be the case with the Rheem unit. I confirmed from multiple sources that the model sold at Home Depot Canada is not the retail grade one sold at American Home Depots. The only difference in part number is a C at the end, which I’m guessing might demarcate it as Canadian market. While the RH375 is newe than the RH350, the RH350 is still a current model according to Rheem.

On the other hand, this contractor is a sole proprietor and maybe he’ll have moved on 5-10 years down the road, either to another industry or a different geographical location. I also just have his verbal assurance that he’s going to give me this warranty service.

The RH375 is a newer model, with about 8% higher efficiency than the other Rheem.

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Replies

  1. user-2310254 | | #1

    I compared the Rheem orange box and Rheem pro models and decided to go with pro. I also had read some of the horror stories in getting warranty support from HD. From what I could gather, there isn't much difference between the HD and pro models. Reportedly the pro unit has a metal valve somewhere and the HD version has a plastic one. (I'm a little fuzzy on that detail at this point.)

  2. Expert Member
    AKOS TOTH | | #2

    I would do quick ROI on these. I recently went through with this with a 50gal unit and it doesn't work. The price for the units is silly up here, about the only way to make it work is if you pick up a unit south of the border.

    If you are installing PV, you are way better to install a couple of extra panels and go with a standard electric tank.

    In terms of EF, since a good part of the year you are taking heat from the rest of the house, the difference in efficinecy of the unit doesn't matter much, it would barely budge the operating cost.

    For example, if you are heating the house with a COP 3 mini split. A water heater needs on average 2000btu.

    So a 3.5 COP water heater takes 1400BTU from the house and uses 170W of electricity.
    That 1400BTU left over is provided by your mini split which uses 136W. So in total 306W.

    With a 4 COP water heater is 146W for the water heater and 147W for the min split, so 293W total.

    A resistance only water heater would use about 2x that electricity, so the heat pump only really makes sense if your electricity is very expensive.

    1. this_page_left_blank | | #5

      I did an ROI a while back, and I based it on not even using the heat pump during the heating season. Still came out to around 7 years. I should re-run my numbers to make sure I didn't miss something.

      No plans to ever have solar panels. Grid connection is not allowed, and off grid would probably have an ROI measured in centuries rather than years.

  3. Yupster | | #3

    If you have time to wait, you should keep an eye on kijiji. I've seen barely used or slightly damaged new ones come and go on there. There is a Sanden unit on there in Ottawa right now actually.

    1. this_page_left_blank | | #6

      I bought one on Kijiji once and it didn't work. I think any heat pump water heater someone is looking to get rid of probably has something wrong with it. I actually spent 3-4 years scanning Kijiji and only ever saw the one within any reasonable distance from me.

  4. Onslow | | #4

    Trevor,

    Akos has cut to the chase, though I would urge a closer look at total winter temperature profile and the actual output of any older heat pump system you might have in place. The newest cold region HP units help the numbers when snitching your internal BTUs. Check the feed temps of your water source and the assumed delta T for the HPWH specs being considered. ( are those US$ or "Looney" prices)

    Another GBA poster kindly provided the NREL document I have attached. It is an older report, but I think the general information and analysis is helpful. It helps to have a carefully charted comparison of actual energy usage across different units. In your particular case, I think it will help you understand the Steibel Eltron's energy management philosophy better. Whether it makes the up charge worth it is up to you and your local energy costs.

    I have read the whole document, and it is a long slog. I will direct your attention to Fig 38-pg 52; Fig 40-pg 54; Table 9-pg 56; and Table 10-pg 57. These items will sum up most of the final points made.

    I took the time to dive into the details because I am also looking at the Sanden unit. I have been asked to supply a large Japanese style soaking tub with hot water, which is exactly why the parent unit, EcoCute, exists. While an 80 gallon HPWHs might carry the load for one fill, I worried about the total energy effects in a tight PGH. I then disappeared down a rabbit hole looking for justifications and/or problems with "eating my own heat" during the cold months. The results were a bit surprising (to me at least).

    The HPWHs do not rely on extracting latent heat energy anywhere near as much as I thought. Freeze up in the coils is a risk that is designed out for the most part, which leaves a large part of the latent heat source unutilised and lowers air temperatures far more than I expected.

    Some HPWHs software relies heavily on resistance heat to make the recovery rates more consumer palatable at the expense of total SYSTEM COP. Energy management choices made by unit software are quite variable and may not fit with your hot water habits in a truly energy efficient manner.

    The COP of the pump portion of HPWH is a bit of a red herring. I think many people believe a COP of 4 will somehow create BTUs. The literature from vendors does little to dispell this misunderstanding. The COP only measures the efficiency of transport of BTUs into the holding tank. That efficiency falls as tank temperatures rise, which necessitates careful thinking about using the highest holding temperature settings to gain peak output for large tubs.

    Where you get your BTUs heavily affects the total system efficiency. (logically) Ducting for external air can be a good answer for some climate zones, but for heating dominate zones ducting might be a low value extra cost and leak source.

    Stealing the heat from your house during the winter is complicated. HPWHs merely charge you for re-packaging the BTUs already paid for. One needs to cost out home heat BTUs and determine whether the comparative cost savings for having a HPWH is really worth the initial expense and cost of upkeep. Hint, if you heat with Nat Gas, you are way ahead. Further hint, heat pump heated homes can see tough sledding during long cold periods. Your milage may vary so to speak.

    One very overlooked aspect of HPWHs is the air volumes utilised. Fan cfm information is somewhat elusive, but the largest stated cfm I have found is 500cfm. If the heat pump run time for recovery after a long shower is 1 hour, the total volume max is 30,000 cfm or nearly two full air change equivalents. Not likely the fan volumes are truly that large, but in tightly sealed homes, a HPWH can become a major active element in your air management planning.

    This was supposed to be my short version of what I found. Believe it or not, I could go into the calculations I made to satisfy myself that I was looking at the issue correctly. Another post, if anyone needs to fall asleep.

    1. this_page_left_blank | | #7

      Interesting stuff. Note how old that is though, from 2011. I'm guessing, based on the description, that unit D is the Steilbel Eltron. I'd further guess that none of the other units have been on the market for several years.

      Can you shed any light on how these numbers in the report translate to UEF numbers? That seems to be the new standard, and according to both Rheem and AO Smith all hot water tanks for sale in the US must spec this. Yet I don't see that on Steibel Eltron's website, they quote some Energy Star efficiency rating.

      The prices I'm quoting are local currency, i.e. Canadian dollars. I didn't actually get a quote for the Steibel Eltron, but just based on US prices it could be anywhere from $3800 up to $6000.

  5. this_page_left_blank | | #8

    Dredging this up again. I was close to pulling the trigger on the Rheem PROPH80 T2 RH350, because I wasn't able to get a quote on the Steibel Eltron or the newer gen5 Rheem ProTerrra. Back in May, I was told by Rheem that both gen4 and gen5 were current models, with not much difference between them. However, I suspect that has changed. The US website no longer lists the gen4, only the ProTerra series. On the Canadian site, they show pictures of the Prestige series when you click on the Hybrid link but if you try to get any further by selecting a size, specs, basically anything on that page they are all dead links. I called Rheem again just now, and the guy I talked to didn't know anything about it. He said the Prestige line still shows on their website at his end. I guess he's on a different world wide web than me. But it sure has all the signs that the gen4 is being phased out, and this makes sense because why would they concurrently sell two different generations of the same product line?

    The question now, is that a reason to not buy the Prestige, i.e. should I wait until the ProTerra makes its way to Home Depot Canada, if it ever does? Maybe it won't, because Home Depot USA has only the consumer grade Performance Platinum (which I should note also no longer appears on the Rheem USA website). It seems like there's two possible ways to look at this; either the last chance to get the pro grade Prestige from Home Depot Canada before it's replaced with a newer consumer grade product, or am I buying something that has a shortened support period due to obsolescence? I know they have to support it for the 10 year warranty period, but this is product with about a 12 year simple payback period so I need to be concerned about out of warranty support too.

    Any opinions? Probably thinking too much about this.

  6. user-2310254 | | #9

    Trevor,

    I debated this issue and ultimately went with the Professional (plumber) model. My research suggested that warranty service was a bigger problem with the big box HPWH. FWIW, my 80 gallon was a leftover earlier model (wifi was an add-on option rather than a built-in feature).

    Two years later I don't have any regrets about this purchase.

    1. this_page_left_blank | | #10

      The big box store warranty is scary, but on the flip side what happens to the plumber's warranty if he retires or changes careers? Most of them around here are very small operations, sometimes just the one guy. The guy I got a quote from is just selling me the tank, and I'm installing it. So there's not going to be a labour warranty in either case. If I go with a full service plumber, installed, the price will put the payback period into the "not before it falls apart" region. Maybe that's a sign we should shower more often.

  7. user-2310254 | | #11

    It's a Rheem warranty whether you buy from a plumber or HD. The online reviews suggest requesting service is easier when dealing with Rheem's contractor network. I assume the work would be assigned to another plumber if the initial installer was not available or no longer in business.

    I haven't read my warranty agreement but suspect it only covers the HPWH. With my tank, the plumber installed it and ran new water lines. I also had a new electrical circuit (220 VAC, 30 amp) put in but made the final connection after the tank was in place.

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