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Gas Piping

Mpj Member Posts: 109
I'm looking at a job I need to install a gas fired pool heater. The heater is about 35' away from the house that piping will be underground. I need to pipe from the meter to where it will meet the outside underground piping approx. 22'.

On table 6.2(a) of NFPA54 at 60' i need to use 1.25" blk pipe to 400,000 BTU's.

on table 6.2(f) for poly pipe I need 1" at 30.

My question is can I go from 1.25" blk after the first 22' and then go to 1" poly from there?(I have an 50" roll in my shop)

Or just keep it 1.25" which I normally would do.


  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    Assuming the 1 1/4" is

    sized correctly and corrosion protected and the meter is sized correctly I would go with 1 1/4" all the way.
  • Mpj
    Mpj Member Posts: 109
    Gas pipe

    Thanks for your reply Tim. That is what I was going to do. I just had a debate with another plumber friend of mine about dropping pipe sizes on long runs.

    I thought poly pipe was corrosion protected, if not what would you recommend?
  • Henry
    Henry Member Posts: 996

    You can steel pipe above ground and poly or copper below ground with a tracer above it. A valve is required before you go underground and once you are above. For such a short run, you can run CSST in a drainage pipe that is sealed at both ends. It is much cheaper.