Need help sizing gas line pipe

Old 10-12-20, 07:42 AM
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Need help sizing gas line pipe

I have a new gas service for an addition on my home, gas line coming in is 1 inch and I'm going to 4 appliances, dryer, stove, h/w heater, and a boiler. I'm not sure if I can run 1 inch all the way then branch off to 1/2 inch going to the appliances or if I can drop down to 3/4 inch somewhere along the line then to 1/2 inch. Sent a diagram where my line has to go below, any help would be appreciated, thanks

Old 10-12-20, 10:05 AM
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Assuming standard appliances (80K boiler, 48K range, 36K water heater, 22K dryer), you'll definitely need 1" for the first part of the run. Depending on the boiler size, you'd be close to the max downsizing to 3/4".

So I'd keep 1" pipe from the meter to your boiler/water heater. 1/2" is fine to the dryer and range. If the run was longer to the range, I'd upsize that too to 3/4", but for a 10' or so run, it's not needed.
Old 10-12-20, 12:41 PM
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when i did pipe calculations for a new gas install in my place, I calc'd 1" pipe for the first part of the run. The plumber I hired came in and installed a 1 1/4" line most of the way down the house. He said what I had was fine but the small cost of going with a larger main line would guarantee that i should have no issues in the future even if I added more T's. He said you don't want to starve the high-use devices.
Old 10-12-20, 01:47 PM
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You've got a 26' run from the meter to feed a hot water heater and a boiler.
You need to check what those appliances need but typically 100k for the boiler and 35k for the water heater.
That's 135k.
30' of 3/4" pipe yields 129k.
30' of 1" pipe yields 224k.
I think I'd be running 1" right to the boiler and water heater area. Tap off 3/4" and then to 1/2" for boiler. Tap off 1/2" for the water heater.

Running 1-1/4" is not a bad idea either.
Old 10-12-20, 02:12 PM
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The longest run I got is like you said, from the meter to the water heater and boiler. It isn't going cost much more to run 1" to all my appliances too and just tap off a 3/4" and reduce down to 1/2' for my connections, you think that would handle everything? I don't know about increasing to 1 1/4", everything on the gas piping and meter is all 1", they also put on a 1" union and 90 degree elbow so I could run it right into the house, should I change all their connections?

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