Not that it would make a huge difference, but I question the value of a
heat pump H/W heater in winter. If it's taking heat from your garage or
basement, that is ultimately taking some heat from your heated spaces,
which means you're simply using more energy elsewhere. If you could
somehow duct the air intake from outside during winter, then it would be
doing the best job it could. In summer, no doubt a true benefit.
Before you argue that I'm wroing, consider this. If the air outside
your garage is colder than inside and the H/W tank is cooling the garage
air in exchange for heating the water, either the garage temp will drop
to less than the outside or warm air will be drawn from the home's
heated spaces. If you are truly insulated, then the former will happen
and you will have the equivalent of ducting intake from outside. I
doubt that the normal case.
Peri
------ Original Message ------
From: "Mike Nickerson via EV" <ev@lists.evdl.org>
To: "Ben Goren" <b...@trumpetpower.com>; "Electric Vehicle Discussion
List" <ev@lists.evdl.org>
Sent: 15-Jan-15 9:04:35 PM
Subject: Re: [EVDL] EV Demand Response - (solar-thermal-NOT)
I have one of the heat pump water heaters. It basically looks like a
normal water heater with a small heat pump on top. They blow the cooler
air out the top of the heat pump, so they can indeed be used to help
with cooling in the summer. You need airflow around the area of the
water heater to take advantage of the cooler air coming from the heat
pump.
Mike
On January 14, 2015 9:39:18 AM MST, Ben Goren via EV
<ev@lists.evdl.org> wrote:
On Jan 12, 2015, at 8:35 PM, Robert Bruninga <bruni...@usna.edu>
wrote:
Compare the 60% efficiency of the PV/Heatpump water heater to the
50%
losses half the year of the 70% thermal panels and higher cost and the
PV panels with heatpump water heating win hands down.
I hadn't heard of heat pump water heaters before this discussion.
Something like that could, indeed, tip the balance.
What happens to the cold side of the heat pump? Can that be used to
reduce air conditioning load in summer?
As of a few years ago, the return on investment, the payback time, for
solar hot water was better than that of PV -- and that included
maintenance every few years, electricity to heat the water on cloudy
days (though much less electricity since you still get a substantial
amount of warming), and so on.
But it's obviously a rapidly-evolving field. If heat pumps really are
coming to water heaters, that's huge not just for PV adopters but
energy efficiency across the spectrum.
If my own system lasts a few more years -- and there's no reason it
shouldn't last a few times a few more years -- then it'll have paid
for
itself. Be nice to make a sizable profit off of it by getting it to
last that "few times a few more years," but, if it dies prematurely, I
suppose an all-electric replacement will have to be on the short list
as well as a drop-in equivalent replacement.
b&
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