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Drain/refill procedure?

I have a natural gas boiler with an old style bladder less expansion tank.

I have made an image showing my system.

I'm looking to replace:
  • - Circulation Pump.
  • - Zone Control Valve.
  • - Pressure Relief Valve.

I cannot find any videos showing a system similar to mine.

I do not need specifics on replacing the parts just the procedure of emptying/refilling the water from the system.

Thank you in advance.


  • Intplm.
    Intplm. Member Posts: 1,443
    To empty the system is one thing. To fill the the system with water correctly would require a manual purge installed on your return piping. Do you have that?
    Post a few pictures here of what you have, to get a better look.
    EBEBRATT-Ed Member Posts: 13,437
    Shut off the cold water fill
    Shut the boiler off
    Manually open your zone valves
    Drain the boiler
    After it starts to drain and the pressure has dropped some you need to remove your air vent or open some radiator vents or open the expansion tank vent to let air in the system otherwise the water won't drain.

    After it has drained and work is completed, reinstall any removed air vents, close the boiler drain and the expansion tank drain and close radiator vents. Open the cold water valve and refill the system. The system will have air trapped at the high points. Go around and bleed all the radiation. When all the radiators are bled start the boiler and pumps. Your high vent should remove the rest of the air but you may have to start and stop the system a few times and re-bleed the radiators to get all the air out. Put the zone valve back into auto mode when complete
  • andrethegiant
    andrethegiant Member Posts: 3
    edited September 2019
    Thank you for your replies.

    Fingers crossed.
  • andrethegiant
    andrethegiant Member Posts: 3
    edited October 2019
    I'm going to be done with the work tomorrow and plan to refill the system.

    Most videos I have watched online show the return being shut off and water drained with a hose on the return before the circulatory pump.

    I have no place to connect a hose apart from below the pump and on the expansion tank.

    I guess I can bleed using the baseboard bleeder valves and the hy-vent on the return.

    Would adding a drainage faucet above the circulation pump help remove air faster?