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Oil boiler to radiant heating

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beardo99
beardo99 Member Posts: 3
in Oil Heating

Apologize

for my lack of knowledge here, but I rent a very old house with an oil boiler in one basement and in another basement is the mixing controls for radiant heating for a small portion of the house. It's never really worked, because we never really fooled with it.

Real question here is that it appears that the intake and output valves at the boiler are closed. Im always a bit hesitant to just open valves. My question is for the radiant heating would opening those valves likely solve the radiant heat issue. Both valves noted in picture attached to the pex tubing that is run through the house to the radiant heat. Attached pics of

1000039575.jpg

boiler and mixing setup.

1000039576.jpg

Comments

  • mattmia2
    mattmia2 Member Posts: 16,117

    the valves connected to the pex appear to be open in the picture, the valve is usually open when the handle is in line with the pipe.

  • beardo99
    beardo99 Member Posts: 3

    Thanks you are correct. Tooscatterbrained today with my head looking at the horizontal pipe on the mixing valve and forgetting inline vs perpendicular. Problem must be elsewhere

  • mattmia2
    mattmia2 Member Posts: 16,117

    the heat motors in those zone valves can burn out, the circulator can stick, the thermostatic mixing valve can stick, the system could be air bound somewhere.

    beardo99
  • beardo99
    beardo99 Member Posts: 3

    Thanks. Living in a FrankenHouse with 5 different heating systems cobbled together has been a challenge. Thanks for pointing me in a decent direction to troubleshoot

  • hot_rod
    hot_rod Member Posts: 27,116

    Turn off the blue handle and you can purge thru the hose valve at the end of this manifold.

    Either call all the zones on, or remove the actuators to open the manifold branches.

    make sure the fill valve is on and working to purge.

    Screenshot 2026-01-28 at 3.05.54 PM.png
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • bburd
    bburd Member Posts: 1,282
    edited January 29

    It looks like one end of the pex to the radiant part of the system connects to the main boiler return pipe after the circulator, which if the circulator is pumping into the boiler will force cool return water back up into the radiant system.

    I don't see how that ever worked correctly.

    —
    Bburd

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