Trane GRAA Installation, Operation And Maintenance Manual page 22

G G a a s s C C o o n n n n e e c c t t i i o o n n s s
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N N o o t t e e : : Contact your natural gas supplier for the Btu/Cu. Ft. content of natural gas in your area.
Referring to the piping example in
the most remote heater (E) is 60 feet. This distance should be used for all of the heaters when
determining the pipe size required. Based on the column marked 60 feet in chart 3, the piping for
this example should be sized as follows:
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Figure 12. Field Piping Recommendations
For the most satisfactory piping installation, the following procedure should be followed.
Make piping layout of the whole installation and calculate the cubic feet of gas that each
supply pipe will carry. See piping example below.
Calculate the cubic feet of gas that each supply pipe will carry:
Btu/Hr.
1000 Btu Natural Gas/Cu. Ft.
= Cu. Ft. Per Hour of Gas to Unit (cfh)
Unit Kilowatt
37.3 Megajoules Natural Gas/Cu Meter
= Liters per second on Gas to Unit (l/s)
This may be higher or lower than the nominal 1000 Btu/Cu. Ft. used in this example:
450 cfh is supplied from A to B, requiring 1-1/4 inch pipe.
200 cfh is supplied from B to C, requiring 1 inch pipe.
Figure 11. Drip Leg Installation
Figure 13, p. 23, the length of pipe from the gas meter (A) to
MUA-SVX004B-EN