gas line size
I have a question regarding natrual gas pipe size. I have a one inch line entering the house. I would like to install a tankless water heater, 90+ furnace, typical gas stove, and a gas starter for a fireplace. Is the one inch pipe large enough for approx. 350,000 btu’s?
Depends on lots of things. Total load (everything on at once) and the longest run. One inch sounds close but does it stay one inch? It depends on where the branch lines are and what size they are AND where your new branch lines start.
I think 350K is good for about 50 feet longest run, which isn't that far in some houses.
Edited 2/20/2008 11:23 am ET by roger g
The house is 100' from the road, the gas company says its a "medium pressure" main. From my meter, the one inch line travels about 30'. At that point, the first branch would be 3/4" about 4' to the tankless. About 6' further would be the next branch, 1/2" about 10' to the furnace. Past the furnace branch it would reduce down to1/2" for another 20' to the stove.
Looks like the distance is a bit too far for 1 inch. But you might be just close enough. It's the measurements in the house that matters. From the meter to the furthest appliance.
The reality is that everything would probably work but the other reality is whatever your code says. It depends what is required in your code. I've always been a bit sticky about code.
Sometimes, buying a smaller BBQ will get you under the wire and then later you can buy a bigger one :)
You can always run a separate smaller line back to the meter and it is considered a new line and is not affected by any other appliance or piping. Strange as that might sound I have done that many times up here in Canada when I couldn't upgrade the existing gas line. That is code.
See if you can do it where you live. It might be a more viable option.
Besides the pipe size, make sure your existing meter can handle the higher load. We installed a tankless system with a 120K BTU input. It was connected to a 1" black pipe line 20' from the meter with a 6' long, 3/4" CSST drop. At full heat the ancient gas meter (supposedly good to 175K BTU) would not maintain the pressure. When I showed the gas company the problem, they replaced the meter with a newer model and everything worked fine.
Thanks for the info.