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Purging boiler

BrianH2015
BrianH2015 Member Posts: 3
I am looking for some guidance on my utica boiler. I am going to be replacing my expansion tank. I have a one pipe system with one zone and the radiators are on the floor above the boiler.  I plan on shutting off the supply line above the expansion tank and shutting off the return line at the boiler to limit the amount of water loss. I then plan on using the relief valve to drain the water from the expansion tank instead of the drain at the boiler, limiting how much water I drain from the boiler. I will also replace the relief valve since it is the original. I then plan on opening the supply and return line. I will then bleed the air at each cast iron radiator. Since I have no way to purge at the boiler, am I approaching this in the correct way? I appreciate any feedback or suggestions. Attached is a picture of the setup. 

Comments

  • HVACNUT
    HVACNUT Member Posts: 5,804
    edited February 2023
    That should work. Is there an old steel compression tank in the rafters? Is there any auto air eliminators on the system?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,453
    I would do what you said except leave the old relief valve on until you are done with the ex tank. When you fill it bring the water up until you just start to get water out of the old relief valve and then change it. Put 12-15 lb pressure on the boiler and the start the system you shouldn't have much to bleed
  • BrianH2015
    BrianH2015 Member Posts: 3
    Thank you for the responses. There is no steel compression tank in the rafters and no auto air eliminator on the system. The boiler looks and all the plumbing looks to have been installed around 1990.
  • BrianH2015
    BrianH2015 Member Posts: 3
    Thank you, it was a success. I followed your instructions and changed the relief valve last. I am glad I decided to change it since the old one was shot, it never fully closed once I opened it. Once I had everything changed and the supply and return opened back upI bleeded the first radiator on the system closet to the boiler, air came out but it was not terrible. I then hit every radiator but no air came out, just water. I ran the boiler for a while and all the radiators are working great. Thanks for the feedback