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What is this?

Matthias Member Posts: 21
Does anyone know what this is and the function of it? Thanks.image


  • JStar
    JStar Member Posts: 2,752
    edited August 2015
    That looks like a TRANE Direct Return Trap for a two-pipe steam system. It was used when the original boiler was coal-fired and didn't have electrical controls. It has a float and trip-switch inside, so if the pressure in the boiler ever increased, water would back out into the returns, closing a set of check valves, then rise into the chamber, lifting a valve to allow steam into it that would push the condensate back into the boiler.
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