Chapter 6 — Adjustment Procedures
Part No. 750-184 6-11
The adjustment screw of the Atomizing Air Proving Switch can then
be adjusted until it breaks the circuit. Here, the programmer will
lock out and must be manually reset before it can be restarted. Turn
the adjusting screw up a half turn or so to remake the circuit.
The adjustment of the air switch may be made either during the
damper closed or damper open position of prepurge. It is also
possible to make the adjustment with the relay stopped in the
damper open position in a similar manner to the adjustment of the
Combustion Air Proving Switch
described in Section M.
After making the adjustment, recycle the control to be sure that
normal operation is obtained. The TEST switch must be set to RUN
position.
O. 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 Pilot Adjusting Cock on the
front of the burner. 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.
Although it is possible to visibly adjust the size of the pilot flame, it
is preferable to obtain a microamp or voltage reading of the flame
signal.
The correct voltage or microamp readings can be found in the
information supplied with the flame safeguard system.
The program relay used may be of the type that provides message
information that includes a constant flame signal of dc voltage. In
this case a separate dc voltmeter is not required.
To Measure and Adjust Pilot:
1. When making a pilot adjustment, turn the Manual-Automatic
Switch to “manual” and the Manual Flame Control to “close.”
Open both the Pilot Cutoff Cock
and the Pilot Adjusting Cock.
The Main Gas Cock
should remain closed.
The regulator in the pilot line, if provided, is to reduce the gas
pressure to suit the pilot's requirement of between 5 to 10" WC.
Regulator adjustment is not critical; however, with a lower pressure
the final adjustment of the pilot flame with adjusting cock is less
sensitive.
2. Connect the micro-ammeter as outlined earlier.
3. Turn the burner switch on. Let the burner go through the normal
prepurge cycle. When the ignition trial period is signaled, set the
test switch to the TEST position to stop the sequence.
4. If the pilot flame is not established within 10 seconds, turn off
the burner switch. Repeat the lighting attempt.
Note: On an initial starting attempt, portions of the fuel lines
may be empty and require “bleeding” time. It is better to
accomplish this with repeated short lighting trial
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