19
CAUTION:
For proper operation, no more than a
30% drop in gas supply pressure from no-load to full-
load conditions is acceptable. Under no
circumstances should the pressure be outside the
listed operational range.
for propane gas. The gas pressure regulator(s) sup-
plied on the heater is for low-pressure service. If
upstream pressure exceeds 1/2 psi at any time, an
intermediate gas pressure regulator, of the lockup
type, must be installed. This regulator should be
placed a minimum distance of 10 times the pipe diam-
eter upstream of the heater gas controls.
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 nominally preset as noted in Table J.
During normal operation, carbon dioxide should be 8.5
to 9.0% at full fire for natural gas and between 9.5 and
10.0% for propane gas. Carbon monoxide should be
‹150 ppm.
Fig. 13: 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.
Table J: Manifold Gas Pressure Settings
Model No.
Manifold Pressure (in. WC)
Natural Gas
Propane Gas
High
High
300A
-1.0 ± .1
-1.0 ± .1
400A
-1.5 ± .1
-1.6 ± .1
500A
-1.2 ± .1
-1.3 ± .1
700A
-1.4 ± .1
-1.0 ± .1
850A
-1.7 ± .2
-3.4 ± .2
Gas Supply Pressure
A minimum of 4.0 in. WC upstream gas pressure
under full load and a maximum gas supply pressure
setpoint of 10.5 in. WC under load and no-load condi-
tions for natural gas. A minimum of 4.0 in. WC
upstream gas pressure under full load and a maximum
gas supply pressure setpoint of 13.0 in. WC is required
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 K: Maximum Equivalent Gas Pipe Length
Model
No.
3/4” NPT
1” NPT
1-1/4” NPT
1-1/2” NPT
2” NPT
N
P
N
P
N
P
N
P
N
P
300A
15
30
45
100
175
400
390
400A
30
70
120
275
270
414
500A
15
40
65
150
150
350
700A
42
96
96
220
310
795
850A
25
55
55
125
175
450
Содержание 300A-850A
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