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Thermostatic Mixing Valves

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Comments

  • Docfletcher
    Docfletcher Member Posts: 487
    edited October 2014
    I purchased this just for grins to see what my indirect was putting out temp wise...

    http://www.amazon.com/gp/product/B00004XSC4/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1

    It's cheep, you can put it in a cup and run hot water to see the water temp your getting at a given aquastat setting. It's only a check and I'm not sure how much it buys you info wise, since you might get some stacking effects in the tank.
  • carpenterguy
    carpenterguy Member Posts: 3
    I am having alot of trouble with reduced flow with a Watts mixing valve, on a solar HWH install. 5 secs of full flow HW, then slowly reduces to trickle in 30 secs. replaced valve 2x, added vacuum relief valve, replaced recirc pump, replaced recirc chk valve. I think first valve (of 3) was honeywell, it died from mineral build-up (incorrectly installed above HWH tank, 160 degree water killed it) second valve (watts) installed in same position, but no pressure. replaced it with same watts, no pressure. moved valve below tank top 10", added VRV. No pressure. Installed Bypass of valve, lots of pressure and extra HW ( very hot, use extreme caution) ANY IDEAS ?
  • carpenterguy
    carpenterguy Member Posts: 3
    Here is a picture of first Mixing valve and position, I learned later install was wrong (2 years service though)
    Second Watts valve was lowered 10" below tank top by myself.
  • hot_rod
    hot_rod Member Posts: 23,145
    It could be caused by the way the recirc is piped to the tank or thermostatic valve. Improper piping can cause "temperature creep" Some good info, and proper piping can be found in this journal.


    http://dandavissales.webs.com/Lit - Caleffi Idronics 11 Domestic Water Heating.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • carpenterguy
    carpenterguy Member Posts: 3
    Fascinating read, still no answers to 'no flow' problem though.
    thanks.
  • kcopp
    kcopp Member Posts: 4,462
    Recheck your piping. Is a check valve stuck? Don't run your system w/o a mix valve...as you can tell scalding is an issue. What are you getting for input temps?
  • hot_rod
    hot_rod Member Posts: 23,145
    Check that all the valve specs are being covered. You have a delta T min. Between H & mixed out, typically around 25 degrees. also pressure difference of no more than 2-1 between H &C, Max. Temperature not exceeded?

    Has the valve been cleaned recently? A small amount of lime scale impedes the movement of the spool inside and can cause performance issues . If the solar tank runs hot, over 150 or so, that causes more mineral percepitation. In some cases mix valves need to be serviced every 6 months or less with hot, hard water and high gpm useage
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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