Dunkirk Q95M-200 Installation, Operation & Maintanance Manual page 18

condition. The LWCO senses water through a probe at the top
of the boiler that sends a signal through the water to ground. If
the signal is not sensed through the ground, the LWCO enters
a lockout mode that disables the appliance. If the LWCO is in
normal mode a red indicator light is illuminated on the LWCO
panel in the boiler. During a low water condition, the red light
goes out and the LWCO and control reset buttons on the display
panel must be depressed to reset the LWCO.
normally closed lwco switch
This round button switch located next to the digital display is nor-
mally closed and spring loaded so that, when depressed, it opens,
and closes again when pressure is removed. The switch is used as the
manual reset for the LWCO. When tripped the LWCO will remain
in lockout until the water level reaches the probe and the switch is
depressed to an open state and then released to a closed state, which
sends a signal to the LWCO to resume normal operation. The boiler
control reset button must then be pressed to reset from a low water
condition. The LWCO switch and control reset button are located on
the display panel of the boiler.
high limit aquastat control
The high limit aquastat control is a redundant safety limit control
that provides a means for protecting the boiler and heating system
from unsafe operating conditions which could damage the boiler.
The aquastat is mounted in the ½" NPT control well and ¾" X ½"
bushing on the top of the front boiler section at the hot water outlet.
The aquastat is tied in with the boiler control and is factory set at
200°F water temperature. The high limit setpoint is field adjustable
and may be set anywhere between 100°F and 200°F, with the maxi-
mum high limit setpoint not exceeding 200°F. The field high limit
setpoint adjustment for each installation depends on heating system
requirements. The aquastat automatically resets when the boiler wa-
ter temperature decreases ten degrees below the high limit setpoint
value. (Adjustable differential from 5°F to 30°F)
NOTE: Boiler operating temperature (temperature curve)
is calculated and set in the parameters of the boiler control.
casting temperature safety switch
In the event of lack of or loss of water in the boiler, the casting
temperature safety switch (230°F setpoint) installed on the top
of the aluminum boiler section behind the supply piping shuts off
the boiler by shutting off power to the boiler control and causes a
failure code to be displayed on the digital readout. This fault requires
manual reset of the casting temperature safety switch to restart the
boiler and the reset to be pressed on the user interface panel. Verify
that the boiler is properly filled with water and no air is trapped in
the top of the casting (check cap on Cam Vent at the heat exchanger)
Xi - controls and accessories
NOTICE
before resetting this switch.
taco pump curve
Grundfos pump curve
bell & Gossett pump curve
18