20
XI - CONTROLs AND ACCEssORIEs
Normally Closed LwCO switch
This round button switch located next to the digital dis-
play is normally 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 nor-
mal 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 adjust-
able and may be set anywhere between 100°F and 200°F,
with the maximum 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 water temperature
decreases ten degrees below the high limit setpoint val-
ue. (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 set-
point) 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 read-
out. 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
Grundfos Pump Curve
Taco Pump Curve
Bell & Gossett Pump Curve
