Page 10
Gas Connection
When connecting gas supply, the length of the run from
the meter must be considered in determining the pipe size
to avoid excessive pressure drop. A line pressure of 7"
w.c. (178 mm w.c.) for natural gas should be maintained
when sizing piping. A line pressure of 13” w.c. (330 mm
w.c.) should be maintained for liquefied petroleum (LP)
gas. For correct sizing of piping, refer to the (American)
National Fuel Gas Code ANSI Z223.1 or (Canada)
CAN/CGA-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 8.
NOTE - If a switch box is mounted over electrical
knockouts on back of unit, leave a minimum of 4" (102
mm) clearance between switch 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 8
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 (3.45 kPa).
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 (3.45 kPa).
See Figure 9.
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 9
MANUAL MAIN SHUT-OFF
VALVE WILL NOT
HOLD NORMAL
TEST PRESSURE
CAP
ISOLATE
GAS VALVE
GAS SUPPLY TO UNIT HEATER
UNIT HEATER
