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49
Q. Water Boiler with Intermittent Ignition (EI) and
Tankless Heater. See Figure 44.
1. Normal Operation
a. Thermostat calls for heat or low limit senses
water temperature below set point.
b. Vent Damper (if used) opens as stated in Vent
Damper Sequence of Operation.
c. Ignition Module is energized. Pilot Valve opens
and Igniter is energized to ignite Pilot Burner.
d. Sensor proves presence of pilot ame. Main
Valve(s) opens and ignites Main Burners.
e. After Thermostat or low limit is satised Ignition
Module is de-energized, extinguishing pilot and
main ame. Vent Damper (if used) closes.
2. Safety Shutdown
a. 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.
b. 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.
c. Flame Roll-out Switch. Automatically interrupts
boiler operation when ames or excessive heat
are present in vestibule. Control is single use
device. If ame roll-out switch is activated do
not attempt to place boiler in operation. Correct
source of blockage and replace ame roll-out
switch.
d. Igniter/Sensor: senses pilot ame and causes
ignition module to turn off main burner and pilot
burner gas ow should pilot burner ame
extinguish. Five to six minutes after shutdown,
Ignition Module restarts ignition sequence.
For Electronic Ignition Trouble Shooting Guide,
see Page 65. For LED Status Codes, see Tables
8 and 9 on pages 55 and 56.