Install Instructions

15
K. Sequence of Operation with Intermittent Ignition
(EI).
1. Normal Operation
a. Thermostat calls for heat. Vent Damper opens.
b. Ignition Module energized. Pilot Valve opens.
Igniter energized to ignite Pilot Burner.
c. Sensor proves presence of pilot ame. Main Valve
opens and ignites Main Burners.
d. Call for heat ends. Ignition Module is de-energized.
Main Valve and Pilot Valve close, extinguishing
pilot and main burners. Vent Damper closes.
2. Safety Shutdown
a. Low Water Cutoff. Automatically interrupts main
burner operation when surface of boiler water falls
to lowest permissible operating level. Vent damper
closes. Normal operation resumes when water
returns to normal level.
b. Limit: Automatically interrupts main burner
operation when steam pressure exceeds set point.
Maximum allowable pressure is 15 psi. Vent Damper
closes. Normal operation resumes when steam
pressure falls below set point.
c. Blocked Vent Switch. Automatically interrupts
main burner operation when excessive vent system
blockage occurs. Vent Damper remains open with
call for heat. If blocked vent switch is activated do
not attempt to place boiler in operation. The source
of blockage must be corrected by trained and skilled
personnel from a qualied service agency before
resetting switch.
d. Flame Roll-out Switch. Automatically interrupts
boiler operation when ames or excessive heat are
present in vestibule. Vent Damper remains open with
call for heat. Control is single use device. If ame
roll-out switch is activated do not attempt to place
boiler in operation. The source of blockage must
be corrected and the ame rollout switch replaced
by trained and skilled personnel from a qualied
service agency.
e. Sensor: senses pilot ame and causes ignition
module to turn off main burner and pilot burner gas
ow should pilot burner ame extinguish. Ignition
module will try to relight pilot for approximately 85
seconds after pilot burner ame is extinguished. If
pilot burner ame can not be reestablished, Ignition
Module will shutdown.
Five to six minutes after shutdown, Ignition Module
automatically restarts ignition sequence. Sequence
continues until pilot burner ame is reestablished or
call for heat ends. Ignition Module can be manually
reset by adjusting thermostat to end call for heat
for one minute.
Vent Damper remains open with call for heat.
For Electronic Ignition Troubleshooting Guide, see
Figure 20.
Figure 13: Wiring Diagram, Intermittent Ignition (EI) and McDonnell & Miller 67 Low Water Cutoff
VI. Electrical (continued)