U.S. Boiler Company INDEPENDENCE, Installation, Operating And Service Instructions

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b . Low Water Cutoff (LWCO): Automatically
interrupts main burner operation when surface of
boiler water falls to lowest permissible operating
level. Normal operation resumes when water
returns to normal level.
c
.
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.
d . 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.
e
.
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.
For Electronic Ignition Trouble Shooting Guide,
see Page 49. For LED Status Codes, see Table 9
on Page 38.
I.
Steam Boiler with Intermittent Ignition (EI) and Probe
Low Water Cutoff. See Figure 32.
1. Normal Operation
a. Thermostat calls for heat. Thermostat Isolation
Relay is energized, closing contacts.
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 flame. Main
Valve(s) opens and ignites Main Burners. Vent
damper, if used, must be in open position when
appliance main burners are operating.
Le registre doit être ouvert lorsque le brûleur
principal de l’appareil fonctionne.
e
.
After Thermostat is satisfied Ignition Module is
de-energized, extinguishing pilot and main
flame. Vent Damper (if used) closes.
2. Safety Shutdown
a . Limit: Automatically interrupts main burner
operation when steam pressure exceeds set point.
Maximum allowable pressure is 15 psi. Normal
operation resumes when system pressure falls
below set point.
VIII. Electrical (continued)