ABC 2: Automatic Boiler Controller 2
Specifications
Value
Operating Voltage 4.8–12 V (rechargeable, high-capacity batteries recommended)
Average Current Consumption~30 mA (servo current varies by model)
Boiler Pressure Setting Range0–6.3 bar (set lower than boiler safety valve lift)
Power Output5 V for optional electric feed-water pump
ProtectionInput polarity protection; 200 mA auto-resetting fuse
How It Works
ABC2 actively manages two key aspects of boiler operation:
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Automatic Pressure Control
Continuously monitors boiler pressure and adjusts the gas servo between Pilot and Open to maintain a steady, user-set target pressure.
Fine, incremental flame control
User-adjustable target pressure below safety-valve lift
Pilot light setting via front-panel potentiometer
Reliable Water Level Management
Intelligent sight-glass sensor with heat compensation and debounce logic prevents false alarms from boat motion.
Works with servo-operated bypass or optional electric pump
Selectable extra fill time: 15 / 30 / 60 / 120 seconds
Low feed-tank level indication
Visual Status Indicators
Blue LED – Gas Status
Solid ON: Gas ON – burner heating the boiler
Blinking: Servo partially open – approaching set pressure
OFF: Pilot light – boiler is at target pressure
Place LEDs where they are visible from the pond side for quick status checks.
Parameter
ValueOperating Voltage:
Average Current Consumption:
Boiler Pressure Setting Range:
Power Output:
Protection:
Always use the boiler’s mechanical safety valve. ABC2 adds protection but does not replace the safety valve.
Items Supplied
ABC2 Control Unit
Boiler Water Gauge Level Sensor (5 mm sight glass)
Boiler Pressure Sensor (ME ¼ × 40 thread)
Red Alert LED
Blue Gas ON LED
Pressure Control Loop
Using the pressure sensor, ABC2 nudges the gas servo to increase or decrease flame intensity. When your set pressure is reached, the controller returns the burner to Pilot, conserving fuel while holding pressure.
Advanced Safety System
Automatic gas cut-off protects the boiler if critical conditions are detected.
Boiler water level not restored within one minute
Critically low input voltage
Pressure or water-level sensor failure
Low cold tank level combined with low boiler level
Red LED – Alerts & Alarms
Blinking: Low input voltage, low feed-tank level, or water demand active
Solid ON: Safety-critical – gas cut-off active
Both LEDs Solid: Emergency gas cut-off condition
Additional Items Required
Gas control valve (90°, servo-operated)
Water bypass valve or electric pump (capable of overcoming boiler pressure)
Cold tank (feed-water) level sensor
Gas (⅛" / 3.2 mm) and water (5/32" / 4 mm) piping
On/Off switch; optional RC emergency gas cut-off
Water Level Control
The sight-glass sensor detects when water falls below the threshold. ABC2 debounces motion effects, then either closes the bypass (engine-driven pump) or starts the electric pump. Once water is detected again, ABC2 continues filling for the selected interval to ensure a robust margin.
In worst-case scenarios (e.g., model trapped in weeds), ABC2 will shut off gas after one minute of unmet water demand to safeguard the boiler.