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A
CAUTION: Combustion air must not be contaminated
by corrosive chemical fumes which can damage the
heater and void the warranty.
NOTE: High chemical concentrates from feeders that
are out of adjustment will cause rapid corrosion to the
heat exchanger. Such damage is not covered under the
warranty.
NOTE: Failure of a heat exchanger due to lime scale
build-up on the heating surface, low pH or other chemical
imbalance is non-warrantable.
Gas Supply
A
DANGER: Make sure the gas on which the heater
will operate is the same type as specified on the heater's
rating plate.
Gas piping must have a sediment trap ahead of the heater
gas controls, and a manual shutoff valve located outside
the heater jacket. It is recommended that a union be
installed in the gas supply piping adjacent to the heater
for servicing. The gas supply pressure to the heater must
not exceed 10.5 in. WC for natural gas or 13.0 in. WC
for propane gas. A pounds-to-inches regulator must be
installed to reduce the gas supply pressure if it is higher
than noted above. This regulator should be placed a
minimum distance of 10 times the pipe diameter upstream
of the heater gas controls. For maximum pipe lengths see
Table H.
Gas Supply Connection
CAUTION: The heater must be disconnected from
A
the gas supply during any pressure testing of the gas
supply system at test pressures in excess of 1/2 psi (3.45
kPa).
Model
1 in. NPT
No.
NAT
PRO
503A
15 (4.6)
35 (10.7) 65 (19.8) 150 (45.7)
753A
5 (1.5)
15 (4.6)
1103A
1253A
1503A
1753A
2003A
3
Natural Gas – 1,000 BTU/ft
, 0.60 specific gravity at 0.5 in. WC pressure drop
3
Propane Gas – 2,500 BTU/ft
, 1.53 specific gravity at 0.6 in. WC pressure drop
Elbow = 10 ft (3 m) effective length
Maximum Equivalent Length, ft. (m)
1-1/4 in. NPT
NAT
PRO
NAT
130 (39.6)
65 (19.8) 100 (30.5)
75 (22.9)
35 (10.7)
55 (16.8)
35 (10.7)
15 (4.6)
25 (7.6)
25 (7.6)
10 (3.0)
15 (4.6)
15 (4.6)
Table H.
Gas Supply Piping Length
A
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.
A
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.
The heater must be isolated from the gas supply piping
system by closing the upstream manual shutoff valve
during any pressure testing of the gas supply piping
system at test pressures equal to or greater than 1/2 psi
(3.45 kPa). Relieve test pressure in the gas supply line
prior to reconnecting the heater and its manual shutoff
valve to the gas supply line. FAILURE TO FOLLOW THIS
PROCEDURE MAY DAMAGE THE GAS VALVE. Over-
pressurized gas valves are not covered by warranty. The
heater and its gas connections shall be leak-tested before
placing the appliance in operation. Use soapy water for
leak test. DO NOT use an open flame.
MUST BE SUPPLIED
BY INSTALLER
MANUAL BALL
VALVE
SEDIMENT
REAR
TRAP
JACKET
Figure 17. Gas Supply Connection
1-1/2 in. NPT
PRO
NAT
360 (109.7)
180 (54.9)
250 (76.2)
90 (27.4)
125 (38.1) 300 (91.4) 300 (91.4)
60 (18.3)
85 (25.9)
25 (7.6)
60 (18.3)
45 (13.7)
35 (10.7)
WRENCHING
NIPPLE
UNION
ELBOW
STREET ELBOW 1'
MANUAL SHUTOFF
VALVE
ZERO GOVERNOR
ON /OFF COMBO VALVE
2 in. NPT
2-1/2 in. NPT
PRO
NAT
225 (68.6) 200 (61.0)
150 (45.7) 150 (45.7)
110 (33.5)
115 (35.1)
90 (27.4)
85 (25.9)
F10691
PRO
300 (91.4)
275 (83.8)
230 (70.1
210 (64.0)
19
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