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Draining hot water gravity heating system

Buzz G.
Buzz G. Member Posts: 61
a system means finding a valve to the floor on the boiler and using a hose to move the water away. The boiler has to be off and so, depending on your setup, you may be able to isolate the radiator or its zone by using the valves in the system. Usually you cannot drain a radiator in isolation-they just don't plumb them this way. You need to open the radiator air valve to let air in to replace the water. If you have a guage you can get good idea of where you have dropped the water level to and perhaps not have to drain it all (hoping the rad is at top of house, not on lower floor). Anyway when you get the level below the level of that rad, you take it off and cap the pipes. Make sure you have the right fittings else you won't have heat. After removalyou have to refill the system and get the air out again by bleeding the rads.

BTW it isn't gravity once you have a circ doing the work.


  • Lana
    Lana Member Posts: 1
    Draining hot water heating system.

    I have a hot water gravity heating system with a circulator. I need to remove one of the cast iron radiators. How do I do this?

    Do I need to drain the water from the line so I can cap the line to this radiator?

    How do I drain the water? How do I refill it? Can anyone give me directions or tell me where to find my answers?

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