Burnham Series 2B - Manual (Page 14)

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Figure 1: Wiring Diagram, Electronic Ignition (EI), Intermittent Circulation
SEQUENCE OF OPERATION
NORMAL OPERATION
1. When the thermostat calls for heat, the relay is
energized. The circulator starts and the vent damper
opens (see Paragraphs 17A through 17D). When the
damper blade reaches the fully open position, the
ignition module is energized opening the pilot valve
and energizing the igniter to ignite the pilot burner.
2. Sensor proves presence of pilot flame. Main valve
opens to ignite main burners.
3. The burners and circulator will operate
simultaneously until the thermostat is satisfied.
4. After thermostat is satisfied, ignition module is de-
energized, extinguishing pilot and main flame. Vent
damper closes (see paragraph 17E).
SAFETY ShUTDOWN
1. Limit: Automatically interrupts main burner
operation when water temperature exceeds set point.
Maximum allowable temperature is 250°F. Normal
operation resumes when water temperature falls
below set point.
2. Blocked vent Switch: Automatically interrupts
main burner operation when excessive vent system
blockage occurs. Control is a multiple use device. If
blocked vent switch is activated do not attempt to
place boiler in operation. Correct source of blockage
and reset blocked vent switch.
3. Flame Roll-out Switch: Automatically interrupts
boiler operation when flames or excessive heat are
present in vestibule. Control is single use device. If
flame roll-out switch is activated do not attempt to
place boiler in operation. Correct source of blockage
and replace flame roll-out switch.
4. Igniter/Sensor: senses pilot flame and causes
ignition module to turn off main burner and pilot
burner gas flow should pilot burner flame
extinguish. Five to six minutes after shutdown,
ignition module restarts ignition sequence.
5. For Electronic Ignition Trouble Shooting Guide, see
Page 25 of this manual.