Adjustment Procedures
6-6
750-368
CBEX Elite 100-1200 HP
To have the modulating damper motor drive to high-fire (damper open), remove the cover from the motor and
remove the wire from terminal W.
Slowly turn down the air switch adjusting screw until it breaks the circuit. Here the programmer will lockout and
must be manually reset before it can be restarted. Add a half turn or so to the adjusting screw to remake its cir-
cuit.
Recycle the program relay to be sure that normal operation is obtained. Replace the wire on terminal W and re-
install the cover. Return the test switch to the “Run” position.
6.9 — Atomizing Air Proving Switch
The air pressure against the diaphragm actuates the switch which, when
closed, completes a circuit to prove the presence of atomizing air. Since the
pressure of the atomizing air is at its minimum value when there is no fuel
present at the nozzle, adjustment of the switch should be done while the unit
is running but not firing. The control should be set slightly below the mini-
mum pressure, but not too close to that point to cause nuisance shutdowns.
The control adjustment may be made during the pre-purge period of operation
by stopping the programmer during the pre-purge period through the use of
the Test switch. Refer to the control instruction bulletin for details.
FIGURE 6-4. Atomizing Air Proving Switch
The adjustment screw of the atomizing air proving switch can then be adjusted until it breaks the circuit. Here,
the programmer will lockout and must be manually reset before it can be restarted. Turn the adjusting screw up
a half turn or so to remake the circuit.
After making the adjustment, recycle the control to be sure that normal operation is obtained. The Test switch
must be set to the “Run” position.
6.10 — Gas Pilot Flame Adjustment
The size of the gas pilot flame is regulated by adjusting the gas flow through the pilot gas regulator and the
adjusting cock. The flame must be sufficient to ignite the main flame and to be seen by the flame detector. But
an extremely large flame is not required. An overly rich flame can cause sooting or carbon buildup on the flame
detector. Too small a flame can cause ignition problems.
NOTE: On an oil fired boiler, the atomizing air proving switch (AAPS) must also be closed. This is an automatic oper-
ation.
NOTE: On a combination fuel fired burner, firing gas, the fuel selector switch could be set to “gas” to eliminate the
atomizing air proving switch from the circuitry.
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