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Thread: Just FYI Heat Pump Water Heaters

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    Plumber Cass's Avatar
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    Default Just FYI Heat Pump Water Heaters

    I just saw this and thought that some might like to read up...


    http://www.rheem.com/Products/tank_water_heaters/hpwh/

  2. #2
    Plumber Cass's Avatar
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    I just got the price for the above unit...

    My cost is $1445.85 + Tax...


    I don't think I will be selling any of these any time soon since the low cut off temp that allowes it to work is 40 F

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    DIY Senior Member Runs with bison's Avatar
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    Yep, I noticed these were coming. What I'm curious about is how well they will interact with the surrounding enclosed space. I would be somewhat concerned about condensation issues at different times of the year. It will be interesting to see how these perform over time.

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    Homeowner Thatguy's Avatar
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    How many cents/kwh does it take to pay back this price within 10 yrs at a COP of 2.0?
    The two of us use 35 therms/month for hot water.
    And with the complexity I'd think there'd be reliability issues.

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    DIY Senior Member zl700's Avatar
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    "I don't think I will be selling any of these any time soon since the low cut off temp that allowes it to work is 40 F"

    How many are installed in ambient temps of 40 degrees F ??

    These have been around awhile, but never sold well, just like the rejuvenation of solar so comes back the HP water heater.

    I can share that these worked great in damp basements that had existing dehumidifiers running. Why not kill two birds with one stone with the byproduct of dehumidification ?

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    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by Thatguy View Post
    How many cents/kwh does it take to pay back this price within 10 yrs at a COP of 2.0?
    Not much I suppose, especially with the 30% tax credit. Say it costs $1600 w/tax vs. say $400 w/tax for an electric. Subtract out the credit and the cost difference and you have delta of about $720.

    A fair question is will you really get 2.0 EF? Or will it be more like 1.5, etc. Some of this depends on climate, some on installation location, some on usage. For this reason they show some geographic zones for estimating use.

    A standard 0.91 EF water heater Energy Guide lists as 4825 kwh/year. If this one actually does about half that then you have ~2400 kwh/year savings.

    So for the 10 year payout electric price would only need to be:
    $720/(10*2400) = $0.03/kwh.

    This is pretty large potential for those using electric for water heating and might actually make electric competitive with natural gas for some.

    However for some applications there is a problem of it cooling interior spaces during the winter requiring more heating... In summer it will be a benefit that will reduce AC use, but likely require dehumidification unless the environment is arid. Makes for more complex economics.

    The two of us use 35 therms/month for hot water.
    Is that the average? Summer? Seems like an awful lot of gas for two. Are you filling big sauna tubs or using high flow (or multiple) showerheads? The highest non-heating season hot water gas consumption I've had in the past 7 years was 24 ccf (this included some regions where the heating season was only 4 months.)

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    Homeowner Thatguy's Avatar
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    Quote Originally Posted by Runs with bison View Post
    Is that the average? Summer? Seems like an awful lot of gas for two. Are you filling big sauna tubs or using high flow (or multiple) showerheads? The highest non-heating season hot water gas consumption I've had in the past 7 years was 24 ccf (this included some regions where the heating season was only 4 months.)
    It's summer because otherwise the NG also goes into the furnace and so I can't tell. We each use about 100 gals/day. Bathtub, dishwasher, washing machine, 2 GPM showerhead [which I probably will drill out].

    You have links to percentiles for water heater energy used in the US?

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    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by Thatguy View Post
    It's summer because otherwise the NG also goes into the furnace and so I can't tell. We each use about 100 gals/day. Bathtub, dishwasher, washing machine, 2 GPM showerhead [which I probably will drill out].

    You have links to percentiles for water heater energy used in the US?
    I don't have links for that. I was more considering it in reference to the Energy Guide/Energy Star water heater ratings and our family's typical usage over the past seven years.

    Water usage and water heating should correlate more with family size than with home size, whereas heating/cooling costs correlate more with home size all else being equal (same region/same users.) Fewer occupants, fewer loads of laundry, dishes, fewer showers, fewer toilet flushes, etc. Type of washers and type of showerheads, toilets of course matter as well.

    My suggestion on the showerhead is to first try buying one that looks like it might suit your need rather than trying to bore out the old one--I didn't have very good luck with ones I bored out in a previous home. Here, I replaced a couple of old 2.5 gpm showerheads that really gave poor showers. The replacements worked much better even though they were inexpensive and had the same flow. They were full spray patterns, Delta's actually. One has five different settings. They both look much better than the old cheapies too... Since then I've also tested some low flow heads, one I really like, the other is underperforming expectations. (I've been in contact with the vendors and parts are on the way.)

    Do you have a housewide recirculation system?

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    Homeowner Thatguy's Avatar
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    Quote Originally Posted by Runs with bison View Post
    Do you have a housewide recirculation system?
    Nah, it's a 2200 sq. ft. house.

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    Master Plumber Redwood's Avatar
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    The thing I get a kick out of is that they are selling this thing essentially like one of those TV/VCR combo's



    Well the VCR looks like it works but the TV is dead... LOL

    If people are interested in heat pump water heating the AirTap unit is a stand alone heat pump that can be added to any existing gas or electric water heater and the AirTap has a MSRP of $699.

    There is a review of the AirTap Heat Pump Retro kit at the Appliance Stimulus Package link in my signature.

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    DIY Junior Member rzyzzy's Avatar
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    FWIW,
    I installed an airtap unit on my house in July, along with a new cheapie ($200) 50 gallon electric water heater( I just leave the breaker off, so it's basically just a tank).

    So far, it's worked fine - it sounds just like one of those $99 window air conditioners when it runs - not really loud, but if your heater is near a bedroom it might bug you.

    The install was easy, but there's about a 15 foot copper tube that gets stuffed into your existing water heater, and I truly don't know if it would be possible to remove it and reinstall it in another water heater if your old one starts leaking, so that's why I bought a new one.

    I'm really happy with it so far - in my area natural gas would have cost $6k to get piped to my house, and I don't have a good spot to put one of those lp tanks. A standard electric heater was out of the question for me, we have variable electric pricing based on season and time of day, with peak electric costing 21 cents per kwh - at the 4825 kwh figure quoted in the post above that would be $1013 per year , just for hot water!.

    The only disadvantage I see is that it has a max temp of 130 degrees - I used to set my gas heater to 140 at my old house, because the dishwasher worked better, and made it harder for my wife to empty the heater with her long showers.

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