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radiant floor heating NOT

Please help

My boiler works well; the hot water baseboards on the ground floor work well; the boiler-mate domestic hot water system works well........ The radiant floor heating, 7 zones upstairs are not heating. The individual zone valves are responding to the corresponding thermostats but hot water is not rising to the occasion. It's as if the circ pump is not pumping past the first short section of pipe into the manifold. Could this be a pump failure or air-loc or ??? Thank you for any suggestions.


  • alaskadavey
    alaskadavey Member Posts: 6
    circulating pump

    Could it be that I have a bad Grunfos circulating pump or pump capacitor? It seems to not be running and only one of three (the closest to the pump) are getting serviced with hot water.
  • alaskadavey
    alaskadavey Member Posts: 6
    circulation pump

    that's one of three loops
  • Gordy
    Gordy Member Posts: 9,537
    Few questions

    What is the system pressure gauge reading at the boiler?

    If its a 2 story home, and the psi on the pressure gauge is 12 psi then purge the zones to see if you get air out of the loops.

  • alaskadavey
    alaskadavey Member Posts: 6
    Circ pump

    Thanks Gordy,

    Its a 3-story home.

    How long should I open the little purge valve for? I tried this already, for a couple seconds, and only water came out, without hissing.
  • alaskadavey
    alaskadavey Member Posts: 6
    circ pump

    sorry, psi at the boiler is 20
  • Kent_3
    Kent_3 Member Posts: 60

    It could be air or it could be the pump.  Purge first.  Look for the path where water will course through the pipes upstairs.  Don't be fooled by short-circuits.  There should be valves and spigots located appropriately for this purpose.  When you are convinced that there is no air up there and yet you get no heat, replace the pump.  And of course do the whole purge thing again. 
  • alaskadavey
    alaskadavey Member Posts: 6
    circ pump

    Thanks for your help

    it turned out to be a combination of things...... air in system, zone valve body and a circ pump gone bad. hopefully all will be good for years to come. The bright side is that I now understand my system MUCH better!
This discussion has been closed.