[RE-wrenches] SWH - mixing valves

[Blair May]

Good point. I use a "mixing valve" to prevent overtemp water (165*+) from
flowing into my propane hot  water heater/storage tank, this prevents the
overtemp safety plug from going. 
 
& then a "Anti scald" valve to condition my water to 110* on the outboard
side of the propane  hot water heater/storage tank.
 

-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-
bounces at lists.re-wrenches.org] On Behalf Of Randy Brooks
Sent: Wednesday, May 19, 2010 2:01 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] SWH - mixing valves


Kelly, 

Although I'm no plumber, I think there is a difference between "mixing
valves" and "anti-scald valves".  I believe mixing valves don't change with
water temperature, so it's hard to get consistent water temperature at the
faucet with varying solar hot water temperature.  I believe anti-scald
valves adjust cold water input with hot water temperature to prevent an
unsafe temperature at the faucet.  I'd talk it over with your plumber.

take care,

Randy Brooks

Brooks Solar, Inc.

Solar Power for People

140 Columbia View

Chelan, WA  98816

509-682-9646

Randy at BrooksSolar.com

www.BrooksSolar.com



On May 19, 2010, at 2:14 AM, Kelly Keilwitz, Whidbey Sun & Wind wrote:



Thermal wrenches,


I'm having an ongoing issue with mixing valves in my own system not keeping
a steady mix domestic HW temperature as the tank temperature varies with
solar heating. If I set it for (say) 122˚F mix when the tank is 135˚, it
seems to hold that differential at all tank temps - i.e. when the tank is
hotter the mix is too hot (sometimes dangerously so), and when colder the
mix is too cold for a comfortable shower. Thus, I need to change the
setting all the time.



I'm now using a Honeywell valve with a 90˚ - 145˚ range. This is a
replacement for a valve with a wider range that acted the same way. Any
ideas,  suggestions for better valves, or....?



This has me wondering how many of our SWH customers are experiencing a
similar thing, but just aren't bothered enough to say anything. We seem to
have encountered many plumbing situations where the mixing valve allowed
weird backflow or siphoning situations to mess with system operation,
especially with HW recirculation. I thought I had all such causes
eliminated on my system, but maybe not.



Thanks for sharing your experience with such matters.


-Kelly



Kelly Keilwitz, P.E.


Whidbey Sun & Wind


Renewable Energy Systems


kelly at whidbeysunwind.com


360-678-7131






_______________________________________________


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










_______________________________________________
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




-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100520/9c01be66/attachment-0004.html>