Section 4 — Commissioning
4-10 Part No. 750-363
4.8 BURNER SEQUENCE
In addition to providing modulation control, the Falcon is responsible for flame supervision and burner
sequencing.
Basic burner sequencing (Central Heat):
1. Heat request detected (Setpoint minus On Hysteresis); LCI limits and demand detected (terminals J6 3 and J8 3).
2. The CH pump is switched on.
3. After a system Safe Start Check, the Blower (fan) is switched on after a dynamic ILK switch test (if enabled).
4. After the ILK input is energized, 10 sec. allowed for IAS input (combustion air proving) to energize, and purge rate
proving fan RPM is achieved - prepurge time is started.
5. When 30 sec. purge time is complete, the purge fan RPM is changed to the lightoff speed.
6. As soon as the fan-rpm is equal to the light-off RPM, the Trial for Ignition (4 sec.) or Pre-Ignition Time is started
(depending on configuration).
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 5 seconds into pilot ignition.
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.
4.9 FAN SPEED SETTINGS
Because the input is determined by the fan speed, the factory fan speed settings may have to be modified
for the particular application, for high altitudes, or when using direct vent combustion. The default fan
speed settings are intended for typical applications for the various boiler sizes. Please contact your
authorized Cleaver-Brooks representative for proper settings in high altitude and direct vent combustion
applications.
4.10 INITIAL START-UP PROCEDURE
4.10.1 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 and regulating actuator with safety shutoff. The blower speed is
controlled by the Falcon with airflow directly proportional to the speed of the fan. The airflow creates a drop
Before initial startup, check for blockages in the flue
venting or vent terminations. Inspect the burner and
furnace for any contamination or blockages.
!
Warning
To Next Page
Loading...