Desa CERAMIC PLAQUE Service Manual page 17

V E N T - F R E E
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
Connect Rubber
dust or dirt is not present. Blow out the pilot
Hose At Manifold
assembly from both directions to remove
Pressure Tap
any dirt. Replace the pilot assembly if nec-
essary.
Manifold
Pressure
Tap (1/8" NPT)
Control
Valve
How To Use A Manometer
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.
G A S
Control
Valve
Manometer
3-Plaque
Thermostat &
Non-Thermostat
& 5-Plaque
Non-Thermostat
Propane Models
Figure 21. Measuring Manifold Pressure
MANIFOLD PRESSURE-GRH
H E A T E R S E R V I C E
SHORT FLAME/LP
6 6
5 5
4 4
7.7"
3 3
2 2
1 1
0 0
1 1
2 2
3 3
4 4
5 5
6 6
5-Plaque
Thermostat
Propane Models
3. Read the manometer water level both
above and below the zero (0) mark, then
add the readings to give the correct
manifold pressure.
M A N U A L
GRH/OV 012A
Figure 20. Short Flame
6
5
4
7.0" 5.3"
3
2
1
0
1
2
3
4
5
6
3-Plaque
Thermostat &
Non-Thermostat
Natural Gas
Models
GRH/OV 026
6
5
4
5.0"
3
2
1
0
1
2
3
4
5
6
5-Plaque
Thermostat &
Non-Thermostat
Natural Gas
Models
17