[RE-wrenches] SWH - mixing valves

[Randy Brooks]

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
>> 
>> 
>> 
>> 
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