Crown Boiler BSI172 Installation Instructions Manual page 23

Blocked Vent ("Spill") Switch - Automatically interrupts burner operation in the event that flue gas spills from the draft diverter
opening. This switch is equipped with a reset button which must be pressed to restore normal burner operation. An open blocked
vent switch is indicative of a problem with the vent system. If the blocked vent switch opens, the cause of the venting problem
must be found and corrected by a qualified gas service technician before the blocked vent switch is reset.
Flame Roll-out Switch - Automatically interrupts burner operation when flames or excessive heat are present in vestibule. The flame
roll-out switch is a single use device which must be replaced by an identical switch in order to restore normal operation. An open
flame roll-out switch is usually indicative of a plugged heat exchanger. The cause of the flame roll-out must be found and
corrected by a qualified gas service technician, and the switch replaced with an identical one, before the boiler is returned to
operation.
VENT DAMPER (NOTE 2)
FIGURE 19: WIRING DIAGRAM, INTERMITTENT IGNITION AND McDONNELL & MILLER MODEL
#67 LOW WATER CUTOFF
NOTE 3
HONEYWELL
VR8204/VR8304
SERIES GAS VALVES
(BSI069 - 345)
ROBERTSHAW
+
7000DERHC
TH
GAS VALVE
(BSI379)
TR
2. VENT DAMPER REQUIRED ON BSI069 - BSI276, OPTIONAL ON BSI310 -BSI379
3. ON BOILERS LESS VENT DAMPER, DAMPER HARNESS IS NOT USED. RED AND
BLUE LEADS SHOWN ARE JUMPED TOGETHER USING RED JUMPER WIRE.
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22
LESS VENT
DAMPER