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Electric boiler mixing valves

Paul Pollets
Paul Pollets Member Posts: 3,656
Has anyone used a smart 2 way(Taco) valve to modulate temperature to a radiant floor (QuickTrak) using an electric boiler? What's the preferred method?


  • ratio
    ratio Member Posts: 3,625
    Is the boiler serving other loads? I think I'd rather modulate the boiler itself via stages &| SCRs, if possible.
  • hot_rod
    hot_rod Member Posts: 22,121
    Most of the radiant specific boilers have ODR to adjust output temperature. Really no need for mixing, unless you have multiple temperature needs. Electro MN, Thermo 2000 are a few I have used.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    The system needs 2 temperatures...wall panel rads and QuickTrak
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,832
    @Paul Pollets I'm not sure the mixing valve knows what makes the water hot. Unless you left the electric boiler I/O manual out where the mixing valve can read it, you can use any valve that is within the temperature range your radiant needs.

    Just remember, if you are going to put arrows of flow directions on the pipes, you need to put them on the inside of the pipe, so the water can actually see which way it is supposed to go.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • hot_rod
    hot_rod Member Posts: 22,121
    You could use a manual "dumb" 3 way mix valve for the low temperature, run the boiler on ODR for the high temperature. The manual valve tracks along with the boiler reset. This work best with a single zone on the mixed valve. It could be a manifold with multiple loops, but as a single zone.
    TRV the panel rads, for near constant circ :) Here it is with a mod con. Any heat source with ODR is workable

    Next option is a 3 way thermostatic. They need to be sized close to the Cv and the SWT needs to be about 20 degrees warmer than the mixed outlet to be stable. So the panel rad SWT needs to be 20- 25 degrees hotter SWT. A typical 3 Cv thermostatic is good for 5, maybe 6 gpm before the head starts to get crazy.

    Option 3 is a motorized mix valve as you mentioned.

    Option 4 Injection mixing, but it gets to be complicated piping and additional circulator cost.

    So it comes down to how much accuracy and how much $$ you want to spend for it.

    I have used the manual mix on two of my own systems and it works very well. A motor and control could be added later if you want it on another ODR logic.
    Tekmar, Danfoss, ESBE, Paxton, Oventrop TRI-CTR, a few others sell a simple 3 way manual valve.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream