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Page 13
Gas Connection
When connecting gas supply, the length of the run from
the meter must be considered in determining the pipe
size. A line pressure of 7" w.c. (1.74 kPa) for natural gas
should be maintained when sizing piping. A line pressure
of 13” w.c. (3.23 kPa) should be maintained for liquefied
petroleum (LP) gas. A minimum of 5.0" w.c. for natural
gas or 10.4" w.c. for LP/propane gas should be
maintained for proper unit operation. For correct sizing of
piping, refer to the (American) National Fuel Gas Code
ANSI Z223.1 or (Canada) CSA-B149 Installation Code or
consult the utility having jurisdiction.
A drip leg should be installed in the vertical pipe run to the
unit. In some localities, codes may require that a manual
main shutoff valve and union (furnished by installer) be
installed external to the unit. Union must be of the ground
joint type. A drip leg should be readily accessible to permit
cleaning and emptying. See figure 9. Leave a minimum of
4" (102mm) clearance between electric box and drip leg.
A 1/8" NPT plugged tap shall be installed immediately
upstream of the gas supply connection to the heater.
NOTE - Compounds used on threaded joints of gas piping
must be resistant to the actions of liquefied petroleum
gases.
FIGURE 9
GROUND
JOINT UNION
DRIP LEG
MANUAL
MAIN SHUT-OFF VALVE
(Furnished by Installer)
GAS FLOW
1/8 NPT
PLUGGED TAP
GAS SUPPLY CONNECTION
Leak Check
After gas piping is completed, carefully check all piping
connections, (field and factory), for gas leaks. Use a soap
solution or other preferred means.
CAUTION - DO NOT use matches, candles, flame or
other sources of ignition to check for gas leaks.
IMPORTANT - The heater and its individual shut off valve
must be disconnected from the gas supply piping system
during any pressure testing of that system at test
pressures in excess of 1/2 psig (3.45kPa).
The appliance must be isolated from the gas supply
piping system by closing its individual manual gas shutoff
valve during any pressure testing of the gas supply
system at test pressures equal to or less than 1/2 psig
(3.45kPa). See figure 10.
NOTE - In case emergency shutdown is required, shut
down main gas valve and disconnect main power to unit.
These devices should be properly labeled by the installer.
FIGURE 10
MANUAL MAIN SHUT-OFF
VALVE WILL NOT
HOLD NORMAL
TEST PRESSURE
CAP
ISOLATE
GAS VALVE
GAS SUPPLY TO UNIT HEATE
R
UNIT HEATER