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SECTION C: Installation
18
Gas Supply Connection
CAUTION: The heater must be disconnected from the
gas supply during any pressure testing of the gas
supply system at test pressures in excess of 1/2 psi
(3.45 kPa).
The heater must be isolated from the gas supply piping
system by closing the upstream manual shut-off valve
during any pressure testing of the gas supply piping
system at test pressures equal to or less than 1/2 psi
(3.45 kPa). Relieve test pressure in the gas supply line
prior to reconnecting the heater and its manual shut-off
valve to the gas supply line. FAILURE TO FOL-
LOW THIS PROCEDURE MAY DAMAGE THE
GAS VALVE. Over-pressurized gas valves are not
covered by warranty. The heater and its gas connec-
tions shall be leak-tested before placing the appliance
in operation. Use soapy water for leak test. DO NOT
use an open flame.
Fig. 15: Gas Supply Connection
CAUTION: Do not use Teflon tape on gas line pipe
thread. A pipe compound rated for use with natural and
propane gases is recommended. Apply sparingly only
on male pipe ends, leaving the two end threads bare.
CAUTION: Support gas supply piping with hangers,
not by the heater or its accessories. Make sure the gas
piping is protected from physical damage and freezing,
where required.
Gas Supply Pressure
A minimum of 4.0 in. WC and a maximum of 10.5 in.
WC upstream gas pressure is required under load and
no-load conditions for natural gas. A minimum of 4.0
in. WC and a maximum of 13.0 in. WC is required for
propane gas. The gas pressure regulator(s) supplied on
the heater is for low-pressure service. If upstream pres-
sure exceeds these values, an intermediate gas pressure
regulator, of the lockup type, must be installed.
When connecting additional gas utilization equipment
to the gas piping system, the existing piping must be
checked to determine if it has adequate capacity for the
combined load.
The gas valve pressure regulator on the heater is nomi-
nally preset as noted in Table I.
1” NPT 1-1/4” NPT 1-1/2” NPT 2” NPT 2-1/2” NPT
Model
No.
N P N P N P N P N P
503 15 35 65 150 130 360 N/A N/A N/A N/A
753 5 15 65 100 75 180 250 N/A N/A N/A
1003 N/A N/A 35 55 35 90 125 300 300 N/A
1253 N/A N/A 15 25 25 60 85 225 200 300
1503 N/A N/A 10 15 15 25 60 150 150 275
1753 N/A N/A N/A N/A N/A N/A 45 110 115 230
2003 N/A N/A N/A N/A N/A N/A 35 90 85 210
Natural Gas – 1,000 BTU/ft
3
, 0.60 specific gravity at 0.5 in. WC pressure drop
Propane Gas – 2,500 BTU/ft
3
, 1.53 specific gravity at 0.6 in. WC pressure drop
Table H: Maximum Equivalent Pipe Length