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Section 2. Installation
TESTING GAS PRESSURE
Before operating the heater, the heater and its gas connections must be leak tested. Do NOT use an open flame to test
for leaks. Test all gas connections for leaks with soapy water.
The heater and its individual shut-off valve must be disconnected from the gas supply piping system during any pressure
testing of that system at test pressures in excess of 1/2 psig (3.5 kPa).
The heater must be isolated from the gas supply system by closing its individual manual shut-off valve during any pressure
testing of the gas supply at test pressures equal to or less than 1/2 psig (3.5 kPa).
CHECKING THE GAS PRESSURE THROUGH THE COMBINATION GAS CONTROL VALVE
Risk of fire and explosion. Improper installation, incorrect adjustment, alteration, service, or maintenance of the Combination
Gas Control Valve can lead to fire or explosion, causing loss of life, personal injury, and/or property damage. If it is necessary
to adjust the gas valve, this must be done by only by a qualified service agency. These instructions are for the use of
qualified service technicians only!
This appliance is equipped with an unconventional gas control valve that is factory set with a manifold pressure of –.2"
(–0.5cm) wc. Installation or service must be performed by a qualified installer, service agency, or the gas supplier. If this
control valve is replaced, it must be replaced with an identical control.
The
combination
gas
valve incorporates dual
shut-off valves and a
negative-pressure regulator.
For proper operation, the
regulated pressure at the
outlet manifold of the valve
must be –0.2" (–0.5cm) wc
below the reference pressure
at the blower mixer inlet,
and the gas valve 'VENT'
tap must be connected to the
end cap air orifice as shown
in
Figure
7.
Do not attempt to adjust the gas input by adjusting the regulator setting. The correct gas regulator setting is
required to maintain proper combustion and must NOT be altered.
The use of Flexible Connectors (FLEX) is NOT recommended unless they are properly sized according to the
supplier recommendations for the heater rating.
GAS PRESSURE REQUIREMENTS
Rev. B 6-23-08
WARNING
C
onnection
To Air Flow
for Service
Switch
To Gas
Valve Vent
CAUTION
To Gas
To Air Flow
Valve Vent
Switch
To Low Side of
Differential Pressure Gauge
N
a
u t
l a r
G
s a
r P
s e
u s
e r
n I
h c
M
x a
m i
u
m
n I
t e l
4 1
M
n i
m i
u
m
n I
t e l
4
0 -
2 .
±
0
1 .
M
n a
o f i
d l
N
O
T
: E
l l A
e r
d a
n i
s g
m
s u
b t
t e
k a
n e
s i
o
e p
a r
n i t
. g
A
y n
d a
s u j
m t
n e
s t
r o
w
h
e l i
h
a e
r e t
s i
f f o
l i w
r l
s e
t l u
n i
r p
b o
e l
m
. s
C
onnection
Figure 7.
for Test
To High Side
of Differential
Pressure Gauge
Pressure Tap
Inlet
Vent
Pressure Tap
P
o r
a p
e n
s e
W
. C .
4 1
4
0 -
2 .
±
0
1 .
w
h
e l i
h
a e
r e t
e r
d a
n i
s g
m
a
e d
e p
o f r
m r
n a
e c
Table 7.
P/N S794
1 5
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