AERCO BMK 3.0 LN Natural Gas July 2011 - Manual (Page 34)

CONTROL PANEL OPERATING PROCEDURES
3-10
25
TO BLOWER
AIR IN
DIAL
(DETAIL “A”)
STEPPER
MOTOR
DETAIL “A”
Figure 3-6.
Air/Fuel Valve In Ignition Position
6. Up to 7 seconds will be allowed for ignition
to be detected. The igniter relay will be
turned off one second after flame is
detected.
7. After 2 seconds of continuous flame, Flame
Proven will be displayed and the flame
strength will be indicated. After 5 seconds,
the current date and time will be displayed in
place of the flame strength.
8. With the unit firing properly, it will be
controlled by the temperature controller
circuitry. The boiler’s VALVE POSITION will
be continuously displayed on the front panel
bargraph.
Once the demand for heat has been satisfied,
the Control Box will turn off the dual SSOV gas
valves. The blower relay will be deactivated and
the Air/Fuel Valve will be closed. Standby will
be displayed.
3.10 START/STOP LEVELS
The start and stop levels are the Air/Fuel Valve
positions (% open) that start and stop the unit,
based on load. These levels are Factory preset
as follows:
Start Level: 20%
Stop Level: 14%
Normally, these settings should not require
adjustment.
Note that the energy input of the boiler is not
linearly related to the Air/Fuel Valve position.
Refer to Table 3-7 for the relationship between
the boiler energy input and the Air/Fuel Valve
position (% open) for a unit running on Natural
Gas.
Table 3-7
Relationship Between Air/Fuel Valve Position and Energy Input
Air/Fuel Valve
Position (% Open)
Energy Input
(BTU/HR)
Boiler Energy Input
(% Of Full Capacity)
0% 0 0
10% 0 0
14%
(Stop Level) 200,000
6.67%
20% 287,000 10%
30% 486,000 16%
40% 802,000 27%
50% 1,180,000 39%
60% 1,720,000 57%
70% 2,300,000 77%
80% 2,550,000 85%
90% 2,720,000 91%
100% 3,000,000 100%