Digital Tank Thermostat Controller

Function

Holding bitumen within ±5 °C of target is essential: below the lower limit, viscosity rises above the pump's effective range; above the upper limit, bitumen oxidises rapidly. The controller's proportional-integral-derivative (PID) algorithm minimises temperature overshoot and undershoot cycling, reducing the number of burner on/off cycles compared to simple on/off bang-bang control, which extends burner life and reduces fuel consumption. The high-temperature cutout output protects both the bitumen grade and the tank shell from thermal overload.

Construction & quality

Housing: DIN-rail or 48×48 mm or 96×96 mm panel-cut-out mount, ABS or polycarbonate front face with IP54 ingress protection. Display: 4-digit LED, red, 14 mm character height, readable in direct tropical sunlight. Input: PT100 three-wire (IEC 60751) or PT1000, configurable via front-panel buttons. Control output: SPDT relay rated 10 A at 240 VAC for burner on/off; optional 4–20 mA or 0–10 V modulating output for variable-output burners. Alarm output: second SPDT relay for high-temperature safety cutout. Power supply: 85–265 VAC universal or 12/24 VDC selectable. Setpoint lockable to prevent unauthorised site adjustment.

When to replace

• Display shows dashes or a sensor error code — open-circuit or short-circuit on the sensor input
• Burner runs continuously without cutting out at the temperature setpoint
• Burner cycles very rapidly — control hysteresis too narrow or sensor signal noise
• Actual tank temperature diverges significantly from the displayed value, confirmed by independent thermometer
• Control relay contacts fail to switch — audible absence of click or contacts welded closed