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Adding a radiant Zone

Hello all, after much anticipation I have finally got my basement ready for heat. Originally my basement was gonna be set up with cast iron sun-rads that I converted from the old steam system to hot water. But as the project went on I had to pour a new slab so I decided to lay down tubing and go radiant. I used uponor hePex, 2 loops at about 270ft each, it's heating approx 500 sqft. I did get a radiant design done and this is what was recommended. My boiler is a gas fired non-condensing cast iron HB Smith. I have a it piped with 4 circulators one for each zone, controlled with an Argo ARM4P. The zones all feed cast iron sun rads.

I have never set up a radiant zone before so I was hoping to get some help from the forum. My intentions are this, from the current zone circulator (which pushes away from the expansion tank) into a 3 way mixing valve, into an additional circulator into my manifold. Coming out of the manifold to a T which brings me into a bypass loop and then back to my mixing valve, which would close my loop. I will be using a uponor 501s set-point control.

Would this be a suitable set-up?

Do I need another relay to operate my second circulator or can it operate off of my current Argo ARM4P which is where the zone circulator is hooked up?

If I do need another relay how is that relay wired in to my current system and what type is recommended?

I get a bit confused with all the different controls that start to come in to play when adding them into the current system.

Thanks for the help.


  • Alan (California Radiant) Forbes
    You don't need

    two circulators.  One on the mixed line is enough.  Look here:

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Cram48
    Cram48 Member Posts: 1
    Adding a radiant Zone

    If I looking at the piping schematic the correct way, it is different than what I have in my current set-up as I have a circulator for every zone. 3 of my zones are on cast iron rads the other zone would be my radiant. All as main circulators for the loop. Heres a few picks. Wouldn't I still need to put another circulator after the mixing valve regardless. Or can I move the circulator after the mixing valve? The Black one in the picture is for the basement radiant.
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