Reznor SCE Unit Installation Manual - Manual (Page 18)

Form RZ-NA I-SCE, Page 18
10. Gas Piping and
Pressures
Gas Connection (Standard Unit)
Model Size 125-250 300-400
Natural Gas 1/2" 3/4"
Propane Gas 1/2" 1/2"
NOTE: The above are gas connection sizes; not supply line sizes.
After all connections are made, disconnect the pilot supply at the control valve and bleed the
system of all air. Reconnect the pilot line and leak test all connections by brushing on a soap
solution.
WARNING
This appliance is equipped for a maximum gas supply pressure of 1/2 psi, 3.5 kPa, or 14 inches
water column. NOTE: Supply pressures higher than 1/2 psi require installation of an addi-
tional service regulator external to the unit.
Pressure Testing Supply Piping
Test Pressure Above 1/2 PSI: Disconnect the heater and manual valve from the gas supply
which is to be pressure tested. Cap or plug the supply line.
Test Pressure Below 1/2 PSI: Before testing, close the manual valve on the heater.
WARNING: Manifold gas pressure must never exceed 3.5" w.c. for
natural gas or 10" w.c. for propane gas.
All piping must be in accordance with requirements outlined in the National Fuel Gas Code
ANSI/Z223.1 (latest edition) or CSA B149.1 and B149.2 (See Paragraph 1.) Gas supply piping
installation should conform with good practice and with local codes.
These separated-combustion units for natural gas are orificed for gas having a heating value
of 1000 (±50) BTUH per cubic ft. If the gas at the installation does not meet this specification,
consult the factory for proper orificing.
Seal the opening for the gas supply pipe with the grommet provided.
Pipe joint compounds (pipe dope) shall be resistant to the action of liquefied petroleum gas
or any other chemical constituents of the gas being supplied.
Install a ground joint union and manual shutoff valve upstream of the unit control system.
The 1/8" plugged tapping in the shutoff valve provides connection for supply line pressure
test gauge. The National Fuel Gas Code requires the installation of a trap with a minimum 3"
drip leg. Local codes may require a longer drip leg, typically 6" (See FIGURE 19.).
WARNING: All
components of a gas
supply system must be
leak tested prior to placing
the equipment in service.
NEVER TEST FOR
LEAKS WITH AN OPEN
FLAME. See Hazard
Levels, page 2.
1-1/2
(38)
6” I.D. Combustion
Air Inlet Collar
6”O.D. Vent Connection
A manual shutoff
valve with 1/8” NPT
plugged tap, accessible
for test gauge connec-
tion, must be installed
immediately upstream
of the gas supply
connection.
Control Side View
Seal with Grommet
2-3/4
(70)
Ground
Joint
Union
Drip Leg
FIGURE 19 - Gas
Connection