A
B
C
D
E
F
G
H
300'
40'
20'
50'
50'
50'
30'
30'
50'
20'
50'
2.2-1
1
August 1999
Fig. 1
LP Tank
First Stage Regulator (Tank Pressure Reduced to 5 psig)
Second Stage Regulator, 5 psig Inlet
Heater
GENERAL IINFORMATION
Pipe sizing is critical to the proper operation of any gas
heating system. However, piping is dependent on several
factors:
1. Total gas load expressed in BTUH.
2. The gas pressure to be supplied through the piping
system. This pressure may be expressed in pounds of
pressure per square inch (psi) or inches of water
column (W.C.).
3. Distance that the gas must travel to feed the heater
furthest from the regulator.
This section provides a basic explanation of how to size
piping for the heaters through the use of pipe sizing tables
and a typical example. In all cases with this example, we will
be using only pounds of pressure, expressed as 5 psi and not
inches of water column.
a. Black iron pipe only was used in this example as it is
less expensive per foot than copper tubing and,
therefore, more commonly used. However, the same
selection process using copper tubing may be done if
so desired. Refer to appropriate pipe sizing tables for
copper tubing. All pipe diameters given are measured
in inner diameter (I.D.). Piping planning and
installation must be done by an experienced, qualified
LP gas installation agency.
b. The minimum pipe size normally used in many
situations is 1/2 in. nominal.
c. The information in the pipe sizing tables was obtained
from Engineered Control International, Inc., L.P. Gas
Serviceman’s Manual L545.
d. Do not attempt gas supply line selection or installation
unless you are properly trained and qualified.
e. All gas supply lines must be leak checked after
installation and when pressurized to provide a safe
installation. Use only certified, approved leak
detectors.
f. This is one example showing how to size piping for a
building. Installation layouts differ as do the
pressures being supplied to piping, whether you are
using for LP gas or natural gas and the material (pipe
or copper tubing) being used.
INSTRUCTIONS
a. Determine total gas demand for entire system, by
adding up BTUH input from heater dataplates and
adding demand for any other gas-fired appliances and
any future heaters.
b. Measure the length of piping required from outlet of
first-stage regulator to the appliance furthest away.
No other length is necessary to do the sizing. In this
example the distance from first-stage regulator to
appliance furthest away is 230 ft.
c. Make a sketch of the piping system and installation.
See Fig. 1.
Pipe Sizing
Installation
Instructions
