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Re-piping manifold keeping existing heat source

DH123 Member Posts: 58
I need some experienced direction.

My existing system is a oil fired cast iron Peerless Boiler with 4 circulators installed around 2000. I have no problem with the heat source I need to make changes to my distribution system (piping) so that I will have more control and comfort.

I plan on sticking with circulators instead of going down the road of the zone valve.

So basically I think I’m good building the manifold and converting the existing loops to the new circulators ( pumping away this time). My question is much more basic: How difficult is it to remove the existing black iron pipe from the top of the boiler without doing damage to the boiler. I’ve got more than enough pipe wrenches and reciprocating saws to remove the pipe, I’m concerned about the “whoops”. Should I consider spraying some type of penetrating oil?

One other question is there an easy way to remove the sheet metal jacket enough so I can get my big boy(36”) pipe wrench on that 1 1/2” bushing on the top of the boiler. It looks like there are (2) screws on the back that secure the jacket to the boiler.

Thanks for the input.
Jim Urquhart


  • mattmia2
    mattmia2 Member Posts: 8,434
    Do you want to grab the bushing as backup when you unscrew the riser? A picture and model would help with how the jacket comes off.
  • DH123
    DH123 Member Posts: 58

    I’m attaching the pictures of the bushing and make model on the boiler.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,111
    edited September 2022
    Just put that 36" pipe wrench on the pipe and TUG. The boiler will hold up just fine. If the bushing comes out... Great. If the bushing stays, That's ok too. Just start with that diameter pipe. Your boiler is not going to work any better with a larger pipe... If You had a 7 or 8 section boiler, that would be a different story. You might need 1-1/2" for 200,000 BTUh. But 1-1/4" pipe will handle up to 140,000 BTUh NET AHRI or 140,000 NET I=B=R (same number just different date of manufacture)

    Information is from this book Page 5 second column. also on the back page is all the rule of thumb charts. http://media.blueridgecompany.com/documents/ZoningMadeEasy.pdf

    So don't do more work than needed.
    Look at bottom of second column on Page 13. there is something @DanHolohan calls the pumping away module in later books. This is a great way to make the system easy to purge each loop without moving the purge hose from zone purge valve to purge valve over and over. One purge valve for the initial purge at the top of the supply riser does them all.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • DH123
    DH123 Member Posts: 58
    Thanks Ed