17
V E N T - F R E E G A S H E A T E R S E R V I C E M A N U A L
2
1
0
1
2
3
4
5
6
GRH/OV 026
5-Plaque
Thermostat
Propane Models
3-Plaque
Thermostat &
Non-Thermostat
Natural Gas
Models
3
4
5
6
7.7"
MANIFOLD PRESSURE-GRH
2
1
0
1
2
3
4
5
6
3
4
5
6
5.3"
2
1
0
1
2
3
4
5
6
3
4
5
6
5.0"
2
1
0
1
2
3
4
5
6
3
4
5
6
7.0"
3-Plaque
Thermostat &
Non-Thermostat
& 5-Plaque
Non-Thermostat
Propane Models
5-Plaque
Thermostat &
Non-Thermostat
Natural Gas
Models
If the pilot flame is short as shown in Figure
20, check for low pressure to the pilot.
First, be sure that the gas supply inlet
pressure to the heater is adequate. Check
the line for proper size.
Second, check manifold pressure with a
manometer to be sure that the regulator is
not defective. See
“SPECIFICATIONS” on
page 13 for the model you are servicing.
Third, check the pilot assembly and pilot
line to be sure that a restriction, such as
dust or dirt is not present. Blow out the pilot
assembly from both directions to remove
any dirt. Replace the pilot assembly if nec-
essary.
Figure 20. Short Flame
GRH/OV 012A
SHORT FLAME/LP
3. Read the manometer water level both
above and below the zero (0) mark, then
add the readings to give the correct
manifold pressure.
1. Fill tube with water until you see the water
level off at zero (0) on both sides.
2. Connect rubber hose to the line to be
tested.
How To Use A Manometer
Manifold
Pressure
Tap (1/8" NPT)
Control
Valve
Manometer
Connect Rubber
Hose At Manifold
Pressure Tap
Control
Valve
Figure 21. Measuring Manifold Pressure
