[Greenbuilding] HEAT PUMP WATER HEATER

[christian corson]

Alan

No it doesnt. The ASHPWH will actually increase the heating demand
considerably when running in the shoulder and heating seasons.
My experiences with Stiebel Eltron is that they can actually decrease the
temp by as much as 6 degrees depending on the space (assuming 800ft2 if you
are not using make up air). Graham Wright did some work with this relative
to PH specifically a few years ago. I believe that in his study it
increased the heating demand by as much a 2/KBTUFT2YR or something like
that (off the cuff metrics). Although I have installed them up here in
Maine they have been outside of the thermal envelope and their primary use
was for summer only residents who were offsetting with PV. For your climate
why dont you just use an ASHP and run it in dehumdification mode (slight
cooling) in the shoulder seasons.  For DHW why not LPG? You could bury the
tank or not depending on the codes there.
c


*Christian Corson*
*EcoCor Design/Build*
ecocor.us
chris at ecocor.us
207 930-5088



On Tue, Oct 2, 2012 at 5:24 PM, Alan Abrams <alan at abramsdesignbuild.com>wrote:

> need help quantifying the (presumed) benefit of using a heat pump water
> heater for a new, airtight house, passive house insulation and glazing.
> There is no natural gas serving the site.
>
> the cooling load is very low--the house is surrounded by tall trees--but
> it will have a Wash DC latent load.   The trees compromise the potential of
> solar thermal...
>
> ...so the question is, does the efficiency and modest dehumidification
> capacity of a HP WH offset the extra heat load, compared to either a
> straight elec resistance WH, or bringing in propane service?
>
> -a
>
>
> Alan Abrams*
> **certifed professional building designer, AIBD
> certified passive house consultant, PHIUS**
> **Abrams Design Build LLC*
> *design for purposeful living*
> 6411 Orchard Avenue Suite 102
> Takoma Park, MD 20912
> office  301-270-NET- ZERO (301-270-6380)
> fax      301-270-1466
> cell     202-437-8583
> alan at abramsdesignbuild.com
> www.abramsdesignbuild.com
>
>
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