Use and Care Manual

38
Pipe Sizing
• A gas shut off valve must be installed on the
supply line.
• Gas piping shall be in accordance with local utility
company requirements and/or in the absence of
local codes, use the latest edition of National Fuel
Gas Code (NFPA54GC), ANSI Z223.1. In Canada,
use the latest edition of CSA B149.1, Natural Gas
and Propane installation code.
• Size the gas line according to total Btu/h demand
of the building and length from the meter or
regulator so that the following supply pressures
are available even at maximum demand.
Supply Pressure
Natural Gas LP Gas
Min 3.5 in. W.C. 8 in. W.C.
Max 10.5 in. W.C. 14 in. W.C.
Flexible Connectors
Flexible gas lines are not recommended unless the
minimum inside diameter is ¾ in. or greater and
the rated capacity of the connector is equal to or
greater than the Btu/h demand of the Water Heater.
Reference Tools & Sample Calculations
The tables and samples below are for reference
only. The professional sizing and installing the
gas line should always run the appropriate
calculations before all installations.
NOTICE
Gas pressures below the required minimum
pressure may result in ignition failure, personal
injury or death.
WARNING
[Calculation Example]
A partial set of sizing tables are printed on page 40.
In cases where these tables are not appropriate,
refer to the NFPA.
1. Draw a sketch of a piping system.
Enter the system information.
(e.g.)
Point of
delivery
Outlet A
clothes dryer
35,000 Btu/h
Outlet B
range/oven unit
75,000 Btu/h
Outlet
C
water heater
180,000 or
199,900 Btu/h
Outlet D
furnace
100,000 Btu/h
2. • Determine the gas type used and supply gas
Pressure, and enter it.
• Determine the piping material and enter it to
the below.
• Select the appropriate pipe sizing table from
page 40 and enter it to the below.
3. • On the sketch, label the section of pipe from
the point of delivery (meter or regulator) to
the first tee as Section 1.
• Label the section from the first tee to the
second tee as Section 2, and label the section
from the first tee to the third tee as Section
3. Use similar section numbers for additional
sections.
Gas type:
Natural
Pressure drop:
1.0 in. W.C.
Table used:
2
Piping material:
Sch 40 steel
Supply gas pressure:
6 in. W.C.
(e.g.)
Gas type:
Pressure drop:
Table used:
Piping material:
Supply gas pressure:
(e.g.)
5 ft
Point of
delivery
5 ft
Section 2
10 ft
Section 1
10 ft
Section 3
5 ft
10 ft
15 ft
15 ft
5 ft
Outlet A
clothes dryer
35,000 Btu/h
Outlet B
range/oven unit
75,000 Btu/h
Outlet
C
water heater
180,000 or
199,900 Btu/h
Outlet D
furnace
100,000 Btu/h
Connecting the Gas Supply