[RE-wrenches] Heat pump water heater

[Ken Schaal]

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" <wkorthof at eesolar.com>
To: <re-wrenches at 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 at 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