Chapter 4 — CFC Commissioning
Part No. 750-263 4-13
7. Pre-Ignition Time will energize the ignitor and check for flame.
8. Trial for Ignition.
9. The ignition and the gas valve are switched on.
10.The ignition is turned off at the end of the direct burner ignition period.
11.The fan is kept at the lightoff rate during the stabilization timer, if any.
12.Before the release to modulation, the fan is switched to minimum RPM
for the CH Forced Rate and Slow Start Enable, if the water is colder than
the threshold.
13.Release to modulation.
14.At the end of the CH-heat request the burner is switched off and the fan
stays on until post purge is complete.
15.A new CH-request is blocked for the forced off time set by the Anti Short
Cycle (if enabled).
16.The pump stays on during the pump overrun time (if enabled).
17.At the end of the pump overrun time the pump will be switched off.
H.FAN SPEED SETTINGS
Because the input is determined by the fan speed, fan speed
settings may have to be modified for the particular application, for
high altitudes, or when using direct vent combustion. Table 4-2
provides the default fan speed settings in typical applications for the
various boiler sizes. To allow safe modulation through the firing
range, these parameters should be initially set to the recommended
speeds. Please contact your authorized Cleaver-Brooks
representative for proper settings in high altitude and direct vent
combustion applications.
I. INITIAL START-UP PROCEDURE
1. Gas Train and Piping
The ClearFire burner is equipped with a combination servo-
regulated gas valve and venturi mixing unit. The gas valve consists
of a single body with dual solenoid shut off valves, filter screen, and
a built-in constant pressure gas/air servo controller. The blower
speed is controlled by the CB Falcon with airflow directly
proportional to the speed of the fan. The airflow creates a drop in
pressure due to the venturi effect. The modulating controller of the
valve actuator senses air pressure change and accordingly brings
Table 4-2 Fan Speed Settings
Setting CFC-500 CFC-750 CFC-1000 CFC-1500 CFC-1800 CFC-2500
Max. Speed (RPM) CH 5500
5300 5300 5300 4600 5000
Max. Speed (RPM) DHW 5500 5300 5300 5300 4600 5000
Min. Speed (RPM) 1300 1200 1100 1100 900 1100
Ignition Fan Speed (Lightoff Rate) 2200 2000 1800 1800 1500 1800
!
Warning
Before initial startup, check for block-
ages in the flue venting or vent termi-
nations. Inspect the burner and
furnace for any contamination or
blockages.
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