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Mixing valve location (before/after pump)

DGA Member Posts: 4
Good morning all.  I have a zone of radiant for my basement slab that is controlled by a pump dedicated to it.  It currently does not have a mixing valve on it and I would like to install one this summer.  In relation to the zone pump, does it matter if the mixing valve is installed before or after the pump.  My current installation would make it easier to install immediately after the pump.  Is there a downside to putting it there? 

Also, what is the highest recommended temperature for the water feeding an in slab loop?

Thanks for any thoughts and recommendations.



  • Gordan
    Gordan Member Posts: 891
    Before and after can be tricky in a circle

    Post drawings of the two options you have in mind. Typically you need two circulators, one for the mixed loop and one for the heat source loop.
  • Snowmelt
    Snowmelt Member Posts: 1,335
    edited April 2014

    You want to pump away , you want a min. As possible start with 140 then work your way down.
  • Rich_49
    Rich_49 Member Posts: 2,695
    edited April 2014

    is that it won't work , the circulator should be inside the mixed loop pulling through the valve .  The fluid temp should be whatever is required at that time . Use an Outdoor reset type valve like a Taco I Series . Figure the required temp at design and on an average day then do the math to determine a reset ratio that will keep the floor productive whenever it is needed .  Don't wait for your coldest day for your hottest fluid either .

    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • DGA
    DGA Member Posts: 4

    Thank you for the help.  I am currently pumping away with the 3 zone pumps off the manifold, but do not have a primary/secondary loop setup (yet).  I will build that when I do a boiler change out in a couple weeks to replace about a 50 year old Crane boiler.  I may add the outdoor reset as well.  The basement zone is a loop with a combination of baseboard radiators and some in floor radiant.  It isn't ideal, but it does do a pretty good job keeping us comfortable and is what I have to work with as existing infrastructure.