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Indirect temps

JackJack Member Posts: 946
What temps do you generally set your indirects? Do you add tempering valves on them?


  • Indirect temperature


    If the capacity of the indirect is sufficient for household needs, then 125F is fine.  If not, we set the indirect higher (150F) and install a tempering valve.
    Often wrong, never in doubt.
  • BriHBriH Member Posts: 3
    Always do

    I've been taught to always put a mixing valve even on water heaters. But I do open up all the way and leave aqua stat at 130 tops
  • Aaron_in_MaineAaron_in_Maine Member Posts: 313

    I set them at 140-150 and install a tempering valve on all my indirects.
    Aaron Hamilton Heating
  • Alan (California Radiant) ForbesAlan (California Radiant) Forbes Member Posts: 1,272
    edited July 2013
    Mixing Valve

    If you decide to use a mixing valve, I like the new one by Honeywell.  It's very easy to install.

    Edit:  Sorry, this is made for a standard, atmospheric water heater and may not be set up properly for an indirect.
    Often wrong, never in doubt.
  • hot rodhot rod Member Posts: 7,208
    two thoughts

    120- 125F takes care of the code requirement and lessens scald potential. But Legionella can be an issue with low storage temperatures.

    140F or higher will handle the legionella concern, but a listed mixing valve must be installed to protect against scald potential.

    It takes more energy to warm the water to 140F, then blend it with cold to useable temperatures around 115F.

    Lower operating temperatures extend the tank life. Lower temperatures precipitate less minerals from the water.. Also less insulation and standby loss, at lower operating temperatures.

    More and more European countries are requiring tanks, especially solar tanks, be elevated to 140F for a 1 hour period every 24 hours. A good compromise solution, I suppose.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
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