Controls And Accessories - Dunkirk PSB-3D Installation, Operation & Maintenance Manual

SAFETY VALVE
Safety valve is designed to open automatically if boiler steam
pressure exceeds pressure rating of valve (15 psig). Should
it fail to open under this condition, shut down your boiler. If
valve discharge occurs, or valve fails to open as described
above, contact a qualified service technician to replace safety
valve and inspect heating system to determine cause, as this
may indicate equipment malfunction.
STEAM PRESSURE GAUGE
Boiler is equipped with pressure gauge installed. Gauge
enables monitoring of the pressure in the system. If safety
devices fail to shut off your boiler at proper settings, notify
your serviceman immediately.
WATER LEVEL GAUGE
Boiler water level can be seen through glass tube in water
level gauge at side of boiler. Correct cold boiler water level
is stamped on side jacket panel. Check water level regularly
for proper level.
Located on right side of boiler jacket panel, there are three
holes for glass water level gauge. Top hole is common for
both types of low water cut off, and is used for upper gauge
glass fitting. Middle hole, 9" down from top hole, is used for
bottom gauge glass fitting for the Model 67D-1 and 47-2
float type low water cut off. Lowest hole, 12
top hole, is used for bottom gauge glass fitting for Model
CG400 probe type low water cut off. Cover unused with
sheet metal knockout.
STEAM PRESSURE CONTROL
Steam pressure limit control (pressuretrol) shuts off gas to
main burners when steam pressure in boiler reaches cut-
off setpoint (i.e. sum of cut-in and differential setpoints).
Burners refire when steam pressure drops to cut-in
setpoint. System pressure requirements are based on size
and condition of pipes, and load.
LOW WATER CUT-OFF
Model 67D-1
Float operated switch which shuts down gas burner if water
falls below visible bottom of gauge glass.
Probe Type Models
Electronic probe type LWCO. Probe is located inside boiler.
LWCO will shut down burners if water loses contact with
probe for 10 seconds.
Refer to manufacturer's instructions (enclosed) for more
information.

CONTROLS AND ACCESSORIES

WATER FEEDER (Optional)
Model WF-2U-24 water feeder maybe used with either
of the low water cutoffs listed. Water feeder maintains
safe minimum water level. Keeps boiler running by
compensating for minor evaporative steam leaks, and
prevents freeze-ups if homeowners are away and return
line leaks.
McDonnell and Miller Model 101 water feeders may be
used, however water feed rates are too high and need to
be regulated or throttled and wiring will have to be revised.
Consult boiler manufacturer before using these or any
other non-standard types of controls.
Automatic water feeder is safety device, not convenience
item. It is not designed to maintain "normal" water line.
Water feeder does not take place of responsible person
monitoring and maintaining normal water line. Steam
boilers require attention.
VENT DAMPER
Automatic, motorized stack damper developed to increase
efficiency of heating systems by reducing standby losses
from boiler and conditioned air space. Damper closes
chimney vent when burner is off and fully opens it when
combustion is required.
/4" down from
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ROLLOUT SWITCH
(FLAME ROLLOUT SAFETY SHUTOFF)
Rollout switch is temperature-sensitive fuse link device.
Located on boiler base just outside fire box. In event of heat
exchanger flueway blockage causing flame to roll out of
fire box, fuse will blow, shutting down flow of gas to main
burners. Fuse does not change in appearance when blown.
If rollout switch blows, replace with exact replacement.
Check heat exchanger flueways for blockage when
restoring system to operating condition. Do not operate
system without rollout switch.
SPILL SWITCH
(BLOCKED VENT SAFETY SHUTOFF)
Spill switch is manual reset disc thermostat with fixed
setpoint (280° F), and normally closed contacts. It is located
at relief opening of draft diverter. In event of chimney or
venting system blockage causing products of combustion
to spill out of relief opening, spill switch disc heats up and
spill switch contacts open, shutting down flow of gas to main
burners by removing power to gas valve.
In event spill switch contacts open, reset button on back of
switch will pop up. Manually reset spill switch after switch has
cooled off, push reset button down. Check venting system
and chimney for blockage when restoring system to operating
condition. DO NOT operate boiler without spill switch.
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P/N 14683003, Rev. D [08/03/2015]