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Is there a better choice for DHW thermostatic mixing valves than Honeywell?

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Jells
Jells Member Posts: 566
I've got 12 mixing valves on the apartment systems I maintain, and these things seem go bad regularly. At $125 per it starts to bite. Can I do better with Taco or some other make or is it just what it is? And is there any frame standardization at all? I have one SPARC that's a different frame.

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  • Paul48
    Paul48 Member Posts: 4,469
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    @hot rod can offer you some information about this. He works for Caleffi.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    What's you're water quality?
    Why are they going bad? Is your domestic hot water at the tank too hot. I think Honeywell literature states a maximum of 190°

    There was an error rendering this rich post.

  • hot_rod
    hot_rod Member Posts: 22,260
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    I would agree that water quality kills most thermostatic valves. In large properties they have a maintenance schedule, sometimes every 6 months to de-scale or replace with rebuilt valves.

    What are the failures, exactly. If the mixed temperature is inconsistent it could be the hot to mixed temperature difference, you want at least 20 degrees hotter in than mixed. Or a pressure difference. Piped incorrectly in a recirculation system will cause them to creep or hunt.

    Aggressive water can damage o-rings

    Check and maybe soften the water?

    I use a tankless water heater kit to run a cleaner through the valves to de-lime them. No need to disassemble just circulate the mild acid to clean them.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jells
    Jells Member Posts: 566
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    Thanks guys. The failure is not supplying hot enough water, the last one I could feel the hot come for a moment before the valve incorrectly overtempered it. The tanks are probably 140, just a normal B-W or Rheem. My local supplier thinks the water in my city isn't too bad.

    Sounds like my current plan to buy rebuild kits and just swap out, descale, and rebuild is the best I can do anyway.
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,110
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  • hot_rod
    hot_rod Member Posts: 22,260
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    Jells said:

    Thanks guys. The failure is not supplying hot enough water, the last one I could feel the hot come for a moment before the valve incorrectly overtempered it. The tanks are probably 140, just a normal B-W or Rheem. My local supplier thinks the water in my city isn't too bad.

    Sounds like my current plan to buy rebuild kits and just swap out, descale, and rebuild is the best I can do anyway.

    Not sure what is meant by not supplying enough hot water. If the valves are set to 120F, you may need to bump up the tank temperature a bit to extend the drawdown. Ideally try to keep a 20- 25 difference between hot supply and mix.

    Best way is to troubleshoot them is to spend some time with temperature gauges and watch them through an entire tank drawdown cycle.

    Most multimeters have temperature differential attachments available to accuratly watch that.

    Rebuilding or replacing the valve may not help if it is a system glitch.

    Some good DHW mixing info here.

    http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_11_1114.pdf

    Also one of the best mixing valves with gauge wells, Caleffi 521 series :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jells
    Jells Member Posts: 566
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    hot rod said:


    Not sure what is meant by not supplying enough hot water. If the valves are set to 120F, you may need to bump up the tank temperature a bit to extend the drawdown. Ideally try to keep a 20- 25 difference between hot supply and mix.

    Sorry, I said "hot enough water" not "enough hot water". The water from the valve was lukewarm. The tanks are all set to max.