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Relocating boiler supply & return lines

Your 2nd Paragrath confuses me a bit. I suggested the 1 inch S/R piping only because most of the boilers I considered have take-offs of that size. I am actually thinkinmg of going with the Triangle ps-110. Might it be wiser to go with a smaller size (3/4) or perhaps larger (1 1/4) to cover the 30 or-so feet to the new boiler? The basement is pretty much wide open, so I can run the piping to my best advantage . . . if I was certain what that was.


  • Eileen Olive
    Eileen Olive Member Posts: 99
    Relocating boiler & supply & return lines

    Looking to install a new mod/con boiler, but I would then need to relocate the boiler's location, since I will not be using the chimney (was oil fired, now gas). But to do this, I will have to re-pipe the supply & return lines about 30 feet away, across my unheated basement, to where the old boiler sat because that's where the 2 inch lines split to supply/return from the radiators upstairs. Will this newly added run (probably 1-inch copper tubing) affect the system's operation very much? Would it help by piping the return line directly above the supply line?
  • Brad White
    Brad White Member Posts: 2,398
    It is all calculable

    What you have going for you is what I assume is an older gravity hot water system with those large iron pipes. Very low pressure drop I would imagine.

    If you sized your ModCon for the heat loss and the flow rate for a certain delta-T (not just 20 but 30 or even 40 degrees) you can diminish your smaller pipe head loss even further. If you have an intended flow rate of about 6 GPM, 1-inch pipe is fine, but I bet you could take that down to 4.5 GPM and not feel the difference, using a 30 degree delta-T.

    I am not sure what you mean about running the supply line under the return line. If it means easier hanging and you have the head room, go for it. Otherwise side by side and insulated in any case is a best practice.

    Insulating those 2-inch pipes takes on larger significance now, doesn't it?

    As a tip, you would be well advised to clean the existing system very well and use a good strainer with some rare earth magnets to pick up stray iron which tends to be attracted to stainless steel heat exchangers and is generally, in any case, not helpful.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Eileen Olive
    Eileen Olive Member Posts: 99

    Can I infer this to mean that locating the new boiler 30-odd feet away from the tie-ins to the main supply & return pipes? Will this adversely affect my flow?
  • Uni R_3
    Uni R_3 Member Posts: 299
    Chimney as Chase

    What about running the exhaust vent piping up the chimney? Is there anything else that needs to vent in there?
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