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mixing control question

I have 3 zones of radiant on a pri/sec system non condensing boiler along with 1 zone hw baseboard(homerun with pex) and a indirect tank. zone A above floor with plates(wood floors with sensor)105*supply temp. 7.6k load zone B thin cement overpour(tile floor) 107*supply temp. 7.5k load zone C basement slab 84*supply 20k load was going to use one motorized 3way for zone a and b and separate one for zone C looking for any advice or suggestions on how to control both(tekmar preferable)or different mixing stategies


  • Jay_12
    Jay_12 Member Posts: 46
    Mixing options

    Typically a separate mixing device is recommended if design temperatures differ by more than 15F.

    You can do this installation two ways. A motorized actuator for all three water temperatures and then the lowest temperature can be further mixed down using a manually fixed mixing valve. John Siegenthaler refers to this as proportional reset. I would suggest using the 363 or 364 Universal Reset Controls.

    The other method method would use two separate motorized mixing valves. A 374 Universal Reset Control can operate two separate mixing water temperatures.

    All three controls provide indirect DHW tank logic.

    Mixing can be achieved using 3-way or 4-way mixing valves plus an actuator motor to automate it. Mixing can also be achieved using variable speed injection mixing which only requires a pump and the right piping and in most cases costs less to install. For more information on variable speed injection mixing, please see the E021 essay on the tekmar website.

    If you have any further questions, please contact me.

    Jay www.tekmarcontrols.com 1-250-545-7749

  • Basements aren't as dynamic as main floors in terms of changing temps. Thus you can get away with more down there.

    We quite often pipe a leg into the basement zone that mixes return water from that zone in with the supply water to that zone, lowering the temperature of that relative to the rest of the system. It's not as precise but it preserves some rest capabilities while keeping the slab water temperature down and it seems to work quite well. and it's a LOT cheaper than two full fledged mixing valves or injection controllers.

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  • thanks for the advice I'm going to use just one 3 way with a thermostatic valve for the basement
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