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    mixing strategy (7 Posts)

  • Mike Mike @ 12:37 PM
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    mixing strategy

    Never installed a two temperature system before and trying to decided the best way to set one up. The project is a house with a mixture of tubing embedded in concrete slab and Warmboard. The low temp requires 9GPM, with a output of 63,000 BTU, using 100 degree water. The high temp requires 6.5 GPM, with a output of 45,000 BTU, using 120 degree water. The heat source is a Triangle Tube Solo, that will be set for the 120 degree water and thinking of using a three way mixing valve with outdoor reset for the low temp, either a Califfi NA164 or a ESBE 62.
    I know their is a lot of options available and was hoping to get someones opinion on this.Thanks
  • SWEI SWEI @ 6:07 PM
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    You're headed in the right direction

    But the valves you mention will still require a controller from someone like Heat-Timer or Tekmar.  The least expensive route is probably a Taco iSeries-R, which has outdoor reset control built into the valve.  You could also use a Lochinver WH boiler, which can control the mixing valve if you add the MTL-01 Loop Control (as can the Viessman 200 series, no external box needed.)  The Taco and TT combo will probably cost a bit less.
  • Rich Rich @ 8:03 PM
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    Mike

          I agree with Swei concerning the mixing valve he recommends . I use it myself quite often in an attempt to keep it simple yet effective and the I Series w/ODR has not disappointed yet .  Let the boiler reset handle the higher temp and the valve do the lower .
          I am curious about how the flow rates were figured out . Seems to me that at 63,000 BTUh you should be pushing 12.6 GPM and the 45,000 should be flowing at 9 GPM . Was a heat loss done on the home also ?
    You didn't get what you didn't pay for and it will never be what you thought it would
  • Mike Mike @ 11:53 PM
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    mixing strategy

    Hey Swei and Rick,
    Thanks a lot for your replies. Sounds like the Taco I series is the way to go. Rick, I am using a 15 degree Delta T that is why my flows are what they are. And yes I did do a heat loss.
  • NRT_Rob NRT_Rob @ 5:57 PM
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    I would choose

    none. within 20 degrees I would not normally recommend mixing. ESPECIALLY if:

    1. lower temp has mass and good thermostats that can use predictive logic (PID, PWM, feedback) to control it.

    2. lower temp is in a lower priority situation such as a basement or garage where either loads rarely change or absolute precision is not necessary.

    we hate the iSeries valves.. they are really built for continuous circulation setups.

    if it bugs you, bump your highest water temp area to a 10 degree dt and your slabs to a 20 and you'll even yourself out by another 5 degrees or so.
    NRT.Rob
  • Rich Rich @ 6:54 PM
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    Or

    you could choose the 120* temp , let the boiler handle reset , use no mixing and zone each installation method separately .  Your slab will be a bit more responsive and when the surface temp reaches target the Stat will shut down that zone . No Flow , No hotter .
        
    You didn't get what you didn't pay for and it will never be what you thought it would
  • Mike Mike @ 10:30 PM
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    mixing strategy

    I hear what you guys are saying and they are very good ideas. My lower temp areas are Warmboard areas with wide plank,7" hard wood for a finish floor. I want the floor to be as stable as possible, constant circulation or as close as possible I think would be a good thing.
    Thanks for your time any other thoughts are appreciated.
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