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Joe F 09-17-2008 08:00 AM

Natural Gas Part II
I just finished reading the natural gas thread about gas supply and pipe sizing. Very informative thread with great insight into some previously "unsolved mysteries".

I currently have 60' total length from the meter. Main line is either 1 1/2 or 1 1/4. At 35' I have a 200,000 btu boiler and a 34,000 btu water heater. At 60' there is a 20,000 btu dryer.

The branch line to the boiler reduces to 1" for a 5' run and then down to 3/4' for the last 4'. Using the chart in the link (from the previous post), I need a 1" line to support 200,000 btu. The gas valve will only accept a 3/4" line. So, my question is what's the right way to connect all this up?

Termite 09-17-2008 08:44 AM

The main line will support the btu/h load for the house, even if it is 1-1/4" (maximum 530k btu/h on 1-1/4" @ 60').

The 1" is adequate for the boiler load. (maximum 260k btu/h @ 60')

You're correct that 3/4" isn't adequate to feed the boiler. But, your boiler's fitting requires you to neck the pipe down to 3/4", and there's no getting around that.

I'd run as much of it in 1" as possible (including the union and the valve), and use a bell reducing coupling and a short nipple to make the physical connection to the boiler.

Downstream from the boiler, 1/2" line would adequately supply the dryer and the water heater (maximum 66k btu/h @ 60').

Joe F 09-17-2008 08:55 AM

Thanks for the quick reply and the comprehensive discussion in the previous gas thread. I'm planning some "system growth" (garage heater & gas log) which will make my total run ~100 ft. It's nice to have the info to do it right.

By the way, I noticed that I have a few galvanized fittings in my system. I realize that's a no-no, but how urgent is it to get them swapped out?

Termite 09-17-2008 09:10 AM

Galvanized isn't prohibited for gas installations, it just isn't common. I wouldn't worry about them.

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