Service Manual

SERVICING
54
DENT OR
BURR
GAS
STREAM
B
The length of Dimension "A" determines the angle of Gas
Stream Defraction, "B".
A dent or burr will cause severe deflection of gas stream.
No resizing should be attempted until all factors are taken
into consideration such as inlet manifold gas pressure,
alignment, and positioning, specific gravity and BTU content
of the gas being consumed.
The only time resizing is required is when a reduction in firing
rate is required for an increase in altitude.
Orifices should be treated with care in order to prevent
damage. They should be removed and installed with a box-
end wrench in order to prevent distortion. In no instance
should an orifice be peened over and redrilled. This will
change the angle or deflection of the vacuum effect or
entraining of primary air, which will make it difficult to adjust
the flame properly. This same problem can occur if an orifice
spud of a different length is substituted.
WARNING
Disconnect gas and electrical power supply.
1. Check orifice visually for distortion and/or burrs.
2. Check orifice size with orifice sizing drills.
3. If resizing is required, a new orifice of the same physical
size and angle with proper drill size opening should be
installed.
S-307 CHECKING GAS PRESSURE
Gas inlet and manifold pressures should be checked and
adjusted in accordance to the type of fuel being consumed.
WARNING
Disconnect gas and electrical power supply.
1. Connect a water manometer or adequate gauge to the
inlet pressure fitting of the gas valve.
2. Remove the pressure tap fitting at the manifold if provided
or check at the gas valve outlet fitting and connect
another manometer or gauge.
Outlet
Inlet
Outlet Pressure
Tap
Inlet Pressure
Tap
Gas Valve
On/Off
Switch
Manometer
Open to
Atmosphere
Manometer
Hose
Open to
Atmosphere
Manometer
Hose
High Pressure
Adjust
Low Pressure
Adjust
WHITE ROGERS MODEL 36G 2-STAGE GAS VALVE
Open to
Atmosphere
Open to
Atmosphere
Inlet Pressure
Manifold
Pressure
WHITE ROGERS MODEL 36G 1-STAGE GAS VALVE