Mixing valve location (before/after pump)

DGA

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.



David

Gordan

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

Before

You want to pump away , you want a min. As possible start with 140 then work your way down.

Rich_49

Downside

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 .



http://www.taco-hvac.com/uploads/FileLibrary/102-145.pdf

DGA

Thanks!!

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.