Gas Line Sizing

Old 07-25-08, 12:28 PM
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Question Gas Line Sizing

Hello, I am new to these forums. I thank you for any good adivise you can offer.
I am planning to install a Bosch 125FX tankles water heater in my island cabin in northern Maine. I would like to fuel the heater with a 100# LP tank if it will be adequate.Its about all I can handle since access is by small boat only.
The manuf. recommends 5/8" semi-rigid copper pipe up to 20' from tank regulator to heater regulator. Gas inlet connection is 1/2" NPT. Min. LP gas pressure is 11"W.C. and min. gas line is 5/8".
I'm confused about the size and type of copper tubing for gas applications. Is it 5/8" ID or OD? Is semi-rigid pipe soft or hard copper? What type is used for gas, L,M,K or ACR?? What type of fittings are used, compression or flared??
Any help would be appreciated.
Old 07-25-08, 07:47 PM
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I have never looked to see what kind of copper they are using from the tank to the house/regulator, but I would say it is either type K or L. K is usually used for underground water lines. It is the thickest. Soft copper goes by OD sizing.
That line up to the regulator is high pressure. After the regulator must be sized by the total distance of pipe, BTU load of all appliances, and gas pressure. 11"-13" WC

If your heater is new, it should come with a sizing chart for after the regulator.

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