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How to Purge Air from Forced Hot Water System?

Rick E.
Rick E. Member Posts: 1
I have a 2-zone forced hot water (hydronic) heating system, heated by oil, and I need to move my expansion tank a couple of feet over to complete some remodeling I'm doing. I can handle the basic plumbing part okay, but I have no idea what the proper way is to refill the system with water and purge the air from it afterwards. Can anyone give me some direction on how to do this, or where to find more info on how to do it? Thanks in advance.


  • Weezbo
    Weezbo Member Posts: 6,232
    Rick go spirovent or a micro bubble devise taco calefi

    if you valve it and have two green handel no kink valves sweat into a couple "T"s you could purge the field first with a pump an a couple washingmachine hoses. then do the same on the boiler.
  • john@TR
    john@TR Member Posts: 26
    purging air

    Sorry, but you really need someone with experience to physically show you how to properly fill and purge a wet system. It's not the kind of thing you can talk someone through. Every system has surprises built into it. And many times you'll find you have to replace the automatic feed to get enough pressure.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    John's Not Exaggerating

    Here are the instructions posted next to my boiler.

    The fill instructions are tedious even though this system is very considerately plumbed with everything sloping back nicely (no air-trap piping) to the boiler!
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