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Vintage radiant heating system mixing valve

bluemoon Member Posts: 40

Hello Wallies....I'm hoping to get some input on a radiant control on a system that we are changing out from oil to gas. I'm sure this device is some sort of mixing valve & I'm not even sure if it is functioning, The 2" manifold supply X 12 3/4" loops is fed directly & teed to this device and also fed with the return water that is teed at the return. It also has 2 cables leaving the top of the valve off into the rafters (it's a ranch on slab)

that i'm guessing are sensors (abandoned?) . The radiant pump is controlled by a T-87 YoYo. There is a new homeowner & I have no maintenance history with this home & I have never seen this device. I would like to eliminate it if possible & install a conventional mix valve. Anyone familiar with this. I think it reads Sarcotherm (?). Please view the attached


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,822
    edited December 2020
    That is definitely the mixing valve Hot Inlet is the “Hot” from the boiler supply . System Outlet is the “Mix” or reduced temperature to the floor loops. The last opening Pump Inlet is for a connection from the cooler “Cold” return from a tee on the radiant loop returns to the boiler.

    Remove it and designed the replacement boiler as you would do with the proper mixing/injection design of your preferences
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • bluemoon
    bluemoon Member Posts: 40
    Agreed. My only hesitation is the direct supply in addition to the mixed