In the process if doing an extensive remodel and I'm upgrading my natural gas plumbing. I've got the sizing all worked out but I'm confused about where sizes should change. My gas meter has a 3/4 inch output. I understand that I can connect my new 1 1/4 inch pipe as long as it is "close" to the meter. In other words there really is no need to replace the meter with one that has a 1 1/4 inch output.
I'm adding a 200,000 BTU tankless water heater that has a 3/4 inch gas inlet. So my question is where should I transition from 1 1/4 inch back down to 3/4? I'm mounting it high on the wall in a new laundry room so the gas line will exit about 5 feet up the wall. Should I run the 1 1/4 inch up that wall, or could I make the reduction in the crawl space before it turns up that 5 feet? I'm not too eager to cheap out and do whatever is easy, but I don't want to make it more complex of there is no value.

Pipe Sizing:
75' of 1 1/4 inch from meter to junction just below Water heater
5' of 1 /1/4 (?) from junction to 200k BTU Water Heater and 25k BTU gas dryer
25' of 3/4 inch from junction to 50k BTU cooktop
20' of 3/4 inch from junction to 50k(?) BTU gas logs

Thanks!

Hey Oregon.

If I understand you, I would run 11/4" pipe over toward the heater and then reduce to a 11/4" x 1" x 1" tee (1" up to heater..would like to see this have a drip tee with a 3.5 inch drip leg (nipple) with a cap for condensation). Then run 1" over toward the cooktop and install a 1"x 3/4"x3/4" tee (3/4" up to cooktop) and then 3/4" over to gas log.

I would connect the heater by 3/4" shutoff (always 1st so can shut gas to unit then break union to work on) and 3/4" union as I would all gas appliances ( the union/shutoff ).

The drip tees I am talking about are designed to capture any condensation that may accur... they are primarily used going from a horizontal to a vertical... so off the 11/4" union as I would all gas appliances ( the union/shutoff ).

The drip tees I am talking about are designed to capture any condensation that may accur...they are primarily used going from a horizontal to a vertical...so off the 11/4"x1" tee I would go vertical by using a 1"x1" long nipple) and a tee fitting so I could go vertical 1" space nipple (about 2.5" drip leg (requires a 3.5 inch nipple) and cap. Any more questions just ket us know!

In order to do an accurate job here I would need to know all gas appliances in the house and the distance from the meter for each... let me know if you want this done.

Hey, if this helped, please RATE THE ANSWER below. Thank you.

Hey--I found this answer via a search; I realize that the thread is from 2008, but I was wondering where this issue (whether or not/how you can go from a smaller-dia. Pipe @ the point of delivery to a larger-dia. Pipe) is covered in, e.g. the Nat'l Fuel Gas Code (the one which is the basis for that area of Michigan's code... where I live)..

I also am adding a tankless water heater, and, using the branch length method, it shows that I need a larger size of pipe from the point of delivery to the branch with the new water heater (moving up from 1" to 1.25"; this is assuming that I can use Table 6.2(b) rather than 6.2(a) for my Sch. 40 metallic pipe... otherwise, I have to move up to 1.5"). So that's the basis for this add-on q. Thanks!