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Insufficient hot water

rlleee Member Posts: 1
The radiant system uses gas hot water tank to heat the radiant floors and provides hot water for residential use. Temperature prior to the inlet of the mixing valve is 145F, output is 108F at the tub and bathroom sink (these fixtures is closest to the hot water tank) I have replaced with a honeywell mixing valve and set the temperature to its highest limit but cannot raise the temperature for the DHW more than the 108F.  I have contacted Honeywell, but they were also stumped.  The radiant floor uses 1/2" "Kitec" for its supply and return and 3/4" for the main hot water supply and return.  The homeowner has informed us that the hot water flow has always been weak. Note: There is no backflow preventer as this is a "simple" radiant system and the previous plumber has swaped out the gas hot water tank in attempt to resolve the insuffcient hot water problem.



  • kcopp
    kcopp Member Posts: 4,441
    got pix?

    may be a misplaced circulator....kpc
  • Paul Pollets
    Paul Pollets Member Posts: 3,656
    Not enough BTU's

    Many water tanks used for combination heating and DHW do not have the ability to supply ample DHW under heating load.  The solution is to add another tank, or change the appliance to a boiler based system that can provide the heating load without running out of DHW. 
This discussion has been closed.