Trying to understand whether it's better to tee off an existing gas line closer to the gas meter or to tee off later on, closer to my new 40k BTU heater.

All the lines in question are 3/4", service line is 3/4". I made a diagram to help explain, dotted green lines are new proposed line and solid lines are solid green. The furnace (not shown in the diagrams) is early on in the solid green line, about 15' from the gas meter. I could tee-off before or after.

My guess is that since all lines are 3/4" I might as well tee-off closer to where I need to get to (option 2). Appreciate any feedback here!

Option 1 (tee-off closer to the meter)

Option #1

Option 2 (tee-off later on)

Option #2

  • 2
    So are there three appliances on this 3/4" line now? If that's the case, you may not have enough capacity regardless of where you tee.
    – isherwood
    Commented Dec 17, 2021 at 21:19

1 Answer 1


3/4" pipe is usually enough to handle two appliances like your furnace and heater, so you can split downstream. Of course, it depends on their total consumption. You'd want to post information about your furnace.

You don't really gain anything by splitting earlier since you have few bends. If it was a twisty route you'd gain some capacity by doubling the line from further upstream. Here I don't think it's necessary.

Again, it ultimately depends on your appliance draw. There are formulas to calculate capacity based on that, pipe length, and bend quantity.

  • Thanks, agree that I can't really get fewer bends by going further upstream. You mention it depends on the appliance draw and that. If I was drawing too much what would I even do about that? Would that mean upgrading my service line? does tee-ing off earlier even help?
    – fairidox
    Commented Dec 17, 2021 at 21:23
  • 1
    You might have to pull a larger trunk off the meter.
    – isherwood
    Commented Dec 17, 2021 at 21:49
  • Thanks! does it matter that the service line is only 3/4", and the line from regulator -> meter is also 3/4"? Seems maybe ineffective to step that up to 1" after the meter.
    – fairidox
    Commented Dec 17, 2021 at 21:55
  • 1
    Pressure to the regulator is probably much higher, so it doesn't need a larger pipe. I'm not an expert, though. I just did a ton of reading last winter when I installed my own Hot Dawg. :)
    – isherwood
    Commented Dec 17, 2021 at 21:58
  • 1
    What is the BTU rating of the meter? You may need a larger meter as well, i think commonly they come in 250k, 350k BTU/Hr sizes
    – redlude97
    Commented Dec 17, 2021 at 22:04

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