William
The key to effective HPWH's is location--- It will need a space large
enough, or with sufficient thermal mass, to provide fairly constant temps
above 50+ *. Ideally 65+, but not above 100 or so.Also, humidity is a large
component of there efficiency factor--the more the better! We've put them in
closed crawl spaces ( pretty dry ), basements ( good choice, especially if
damp with a big wood stove ) or a sunroom/greenhouse if it doesn't over
heat. They will not be completely silent, so take that into acount.
Remember not to 'rob peter to pay paul'--- you'll need a location that gets
free humidity and heat. If you can benefit from the cool air byproduct, so
much the better ! But the common location for an electric strip WH, like
under the stairs, in the utility room, etc. would not be a good choice. A
garage ? depends on the climate your in-- Southern California ? probably
works well.
Ken
----- Original Message -----
From: "William Korthof" <wkort...@eesolar.com>
To: <re-wrenches@lists.re-wrenches.org>
Sent: Sunday, April 11, 2010 4:37 PM
Subject: [RE-wrenches] Heat pump water heater
Does anyone have experience with heat pump water heaters?
There are a couple units available now and they seem great---I just
purchased one from
Lowes (GE "hybrid" water heater), which has a 700 watt heat pump and 2
standard 4500
watt heating elements... the "brains" of the water heater let you select
several operating
modes:
-heat pump only
-heat pump with limited resistive backup
-heat pump with maximum resistive backup
-resistive heating only
The unit has a rated COP of 2.35, which should mean 2.35 kWh of heating
for each
kWh of electrical load (presumably in mode #2 or #1), and the DOE energy
sticker shows
the thing using ~1800 kWh per year, compared to standard tanks using ~5000
kWh/year.
For the $1600 price, it seems like a no-brainer replacement for any
regularly used
electric tank heater--- and with this efficiency, I'm wondering how it
might compete
against the other hot water options: gas tank, propane, solar,
tankless....
Rather than DHW solar, it now make more sense in many cases to just have a
heat pump
water heater + a few more PV modules.... all electric, and no solar hot
water maintenance.
/wk
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
--------------------------------------------------------------------------------
No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.801 / Virus Database: 271.1.1/2805 - Release Date: 04/11/10
14:32:00
_______________________________________________
List sponsored by Home Power magazine
List Address: RE-wrenches@lists.re-wrenches.org
Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
www.re-wrenches.org/etiquette.htm
Check out participant bios:
www.members.re-wrenches.org
