9
GAS PIPING
Size gas piping to supply the unit with 6" to 10.5" water
column pressure for natural gas or 11" water column
pressure for propane when all gas consuming devices in
the building connected to the same gas system are
operating. Install piping in accordance with local codes,
the piping must conform with the latest ANSI-Z223.1
National Fuel Gas Code; in Canada, Current Standard
CAN / CGA-B149, Installation Codes for Gas Burning
Appliances and Equipment.
Some utility companies will require pipe sizes larger
than the minimum sizes listed.
NOTE: Local Codes may require the use of a manual
main gas shut-off valve and union, (furnished by others)
installed in the gas line external to the unit.
GAS PIPING is to be supported DIRECTLY AT CON-
NECTION TO UNIT and must not be strained or bent
and shall be supported by metal straps, blocks or hooks
at intervals not to exceed that shown in the following
table:
Pipe joint compounds used on all gas piping connections
shall be resistant to the action of petroleum gases.
An 1/8" NPT plugged tap is required immediately ahead
of the unit gas control valve.
All piping connections shall be checked with a soap
solution for gas leaks before operating the appliance.
INSTALLATION continued
SIZE OF PIPE
INTERVALS (feet)
GAS PIPING SUPPORT
1/2"
6'
3/4" or 1"
8'
1 1/4" or larger (horizontal)
10'
1 1/4" or larger (vertical)
every floor level
Nominal
Iron Pipe
Size, Inches
10 50 100 200
GAS PIPING CAPACITIES
3/4" 278 115 79 55
1" 520 215 150 100
1 1/4" 1050 440 305 210
1 1/2" 1600 670 460 320
2 3050 1270 870 610
2 1/2" 4800 2000 1400 980
LENGTH OF PIPE, FEET
Max. Capacity of Gas Pipe in Cubic Ft. Per Hour*
*At gas pressure of 0.5 PSIG or less and a pressure
drop of 0.5 inches of water. Specific gravity = 0.60.
UNIT SIZE / TONS
INPUT / MBH
GAS PIPING SIZES
02 - 03 69 3/4"
04 90 3/4"
05 - 06 - 07 90 - 180 3/4"
08 - 10 180 - 270 - 351 3/4"
13 - 15 180 - 270 - 390 3/4"
16 - 30 270 - 390 - 480 3/4"
PIPE SIZE
Gas piping information is for practical guidelines and is
typical for one gas valve. For units with dual heat
exchangers, duplicate gas piping to number two gas
valve.
GAS PRESSURE REGULATOR & OVER-PRESSURE
PROTECTION DEVICE
On applications where gas service to the unit is greater
than 10.5"w.c. and less than 2-psi, a gas pressure regu-
lator must be installed.
At supply pressures in excess of 2-psi and less than 5-
psi, ANSI Z21.80 line regulator standard requires a
means (an over-pressure protection device / OPD) to
limit the downstream pressure to 2-psi maximum, in the
event of regulator failure.
In compliance with the ANSI Standard, installations
exceeding 2-psi and less than 5-psi nominal require a
tested and approved over-pressure protection device for
use with the regulator.
For proper heater operation, pressure to the regulator
MUST NOT BE greater than 5-psi.
Utility
Access
Gas
Shut-off
Valve*
Heat
Exchanger
Gas
Valve
Union*
GAS PIPING ILLUSTRATION
*Gas piping field installed by others
Optional
Gas Pressure Regulator
