24
SERVICING
S-305 CHECKING MAIN BURNERS
The main burners are used to provide complete combustion
of various fuels in a limited space, and transfer this heat of
the burning process to the heat exchanger.
Proper ignition, combustion, and extinction are primarily due
to burner design, orifice sizing, gas pressure, primary and
secondary air, vent and proper seating of burners.
.023" - .027"
Beckett Burner
WARNING
Disconnect ALL Gas and Electric Power Supply.
In checking main burners, look for signs of rust, oversized
and undersized carry over ports restricted with foreign ma
-
terial, etc, refer to previous drawing. Burner cross-over slots
must not be altered in size.
S-306 CHECKING ORIFICES
A predetermined fixed gas orifice is used in all of these fur
-
naces. That is an orifice which has a fixed bore and position
as shown in the following drawing.
No resizing should be attempted until all factors are taken
into consideration such as inlet and 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 fir
-
ing rate is required for an increase in altitude.
Orifices should be treated with care in order to prevent dam
-
age. 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 ALL Gas and Electric 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.
A
GAS
STREAM B
The length of Dimension “A” determines the angle of Gas
Stream “B”.
DENT OR
BURR
GAS
STREAM B
A dent or burr will cause a severe deflection of the gas
stream.
S-307 CHECKING GAS PRESSURE
Gas Supply Pressure Measurement
CAUTION
To prevent unreliable operation or equipment damage, the
inlet gas supply pressure must be as specified on the unit
rating plate with all other household gas fired appliances
operating.
Gas inlet and manifold pressures should be checked and
adjusted in accordance to the type of fuel being consumed.
The line pressure supplied to the gas valve must be within
the range specified below. The supply pressure can be mea
-
sured at the gas valve inlet pressure tap or at a hose fitting
installed in the gas piping drip leg. The supply pressure must
be measured with the burners operating. To measure the
gas supply pressure, use the following procedure.
