[RE-wrenches] SWH - mixing valves

Kelly Keilwitz, Whidbey Sun & Wind kelly at whidbeysunwind.com
Thu May 20 08:44:15 PDT 2010


Randy,
These valves are the Honeywell Sparcomix AM series, which are  
certified for "anti-scald" (ASSE 1016 & 1017)
The specs show that, for a hot supply range of 120˚ to 180˚, at a  
position #2, the mix temp should vary only from 116˚ to 122˚. The  
valve is definitely not working to spec, and not providing "anti- 
scald" protection.

Anyone else seen this in their installations?

-Kelly

Kelly Keilwitz, P.E.
Whidbey Sun & Wind
Renewable Energy Systems
kelly at whidbeysunwind.com
360-678-7131




On May 19, 2010, at 11:01 AM, Randy Brooks wrote:

> 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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>>
>>
>>
>>
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