Dunkirk Q90-200 Series II - Manual (Page 26)

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See “Troubleshooting” on page 31 for detailed sequences of
operation and troubleshooting procedures. See separately
provided “Repair Parts Manual” for locations of control
components and accessories described.
Integrated Boiler Control (IBC)
• Integrated Boiler Control (IBC) is a microprocessor
based controller for high efficiency gas boilers.
• Controller monitors all safety controls which control
operation of combustion air blower, circulator pump,
burner, and combination hot surface igniter/flame
sensor.
• Controller is not intended for use with vent damper.
Controller is mounted on control panel inside boiler.
Contains five diagnostic indicator lights.
Gas Control Valve
Electronic 24 volt gas control valve contains 1:1 gas/air
pressure regulator, controls gas flow to main burner of
appliance. Suited for both natural and LP gas, and rated in
accordance with ANSI Z21.21 - latest revision and CGA-
6.5-M95.
Hot Surface Igniter
• 120 volt hot surface igniter heats up 1800°F initiates
combustion of gas in burner.
• Igniter is mounted next to burner through gas/air mixer.
• Igniter also serves as means for proving main burner
flame by flame rectification.
A. In event of lack of flame signal on three consecutive
trials for ignition, IBC will lock out.
B. “Valve” and “Flame” diagnostic indicator lamps blink
indicating failure mode as lack of flame signal.
C. Manually reset IBC from lockout by removing and
re-establishing thermostat’s call for heat, or turn
service switch off, then back on. See Figure 19.
High Limit Control
NOTICE
Maximum set-point of limit control must not exceed
190°F.
• High limit control determines maximum boiler water
temperature and provides means for protecting boiler
and heating system from unsafe operating conditions
which could damage boiler.
• Control is mounted in ½” NPT control well and ¾” x ½”
bushing on top of front boiler section at hot water outlet.
• Control is tied in with IBC and factory set at 190°F water
temperature.
• High limit set-point is field adjustable and may be set
between 100°F and 190°F.
• Field set-point adjustment for each installation depends
on heating system requirements.
• Differentials are automatic, vary based on control
settings and boiler temperature.
• Refer to limit manufacturer instructions provided with
limit control.
Casting Temperature Safety Switch
NOTICE
Never run cold water into hot, empty boiler.
Casting temperature safety switch (230°F set-point) shuts
off boiler by shutting off power to IBC, result of lack or loss
of boiler water. Power indicator light goes out.
Switch is installed on top of aluminum boiler section behind
supply piping.
Fault requires manual reset of casting temperature safety
switch, restarting boiler. Verify boiler is filled with water
before resetting switch.
10 - CONTROLS AND ACCESSORIES
Figure 19 - Gas Valve
Figure 20 - Indicator Lights