# Size of gas lines for propane appliances



## Jnaas2 (Mar 29, 2014)

Go by what the manufacture says, That's what the building inspector will tell you, You need total btu at start then downsize as you go to each appliance


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## Daneel (May 10, 2011)

Manufacturer instructions on the Home Depot website are not very specific.

One water heater says...

"The branch gas supply line to the water
heater should be clean, properly sized
steel pipe or other approved gas piping
material."

...and...

"The inlet gas pressure to the water heater
must not exceed 14" w.c. for Natural gas,
or 14" w.c. for LP gas. For purposes of
input adjustment, the minimum inlet gas
pressure (with main burner on) is shown
on the water heater rating plate. If high or
low gas pressures are present, contact your
gas supplier for correction."

I will look at a water heater name plate the next time I am in HD.

Another water heater says...
"Gas Connection Size 0.75"

This is not enough information for matching anything to 3/8" diameter rolled copper tubing coming from a "twin" regulator. I will not need more than 400,000 BTUs for all gas appliances.


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## beenthere (Oct 11, 2008)

I prefer the regs be separate. As in a tank reg, and then the secondary/house reg at the house.

Add up all the appliances(BTU requirements) that you will have. Run the size pipe you nee for that BTU, and branch of of it to your individual appliances.

You can use the below link to size your piping/tubing.
http://www.lp-gasequipment.com/products/pdf/LPGas_Cat2010_p157-175.pdf


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## GrayHair (Apr 9, 2015)

*Someone with more (and more recent) experience should confirm of rebut what follows. Hint! Hint!*

Without getting into Boyle's Law, the volume of propane delivered to an appliance should be based on supply size and pressure. Increasing either line size or presure increases the volume delivered. As long as the propane company knows the requirements of all gas "appliances", they should provide a properly sized system. For the average home, I'd bet on a "cookie cutter" design.

One function of a regulator is to reduce pressure. 
*High Pressure (tank) --> REGULATOR --> Medium Pressure (line to house) --> REGULATOR --> Low Pressure (house lines) --> Appliance*
 The line between the tank and house is at a higher pressure than house lines, so it can deliver a greater volume even if it's the same size as the house lines. The stipulation on minimum line size to an appliance applies only from the last regulator to the appliance.


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## Daneel (May 10, 2011)

GrayHair, beenthere, Jnaas2,

This is exactly what will be helpful. Thank you very much.


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