TD9 Differential Controller


The easy to install and exceptionally reliable TD9 Digital Control System is the ‘digital brain’ of a solar hot water system. Unlike other controllers that use imprecise analogue temperature sensors, the TD9 uses highly accurate digital sensors to continually monitor actual temperatures and temperature changes, in order to control the circulation of water around the system using the solar pump.

The use of digital sensors means that the differential temperature (DeltaT) can be reduced to just 3°C (typically set to 6°C-10°C if analogue sensors are used), so more energy can be transferred from the solar collectors into the hot water cylinder or pool etc.


SMARTlogic - The software automatically maximises the efficiency of the solar system. It monitors temperature changes in the collector to predict water temperatures. This can allow the system to start heating the cylinder earlier and for longer each day.

SAFElogic - This in-built safety feature continually monitors the cylinder and collector temperatures. Should they exceed 84°C the circulation pump will be run overnight to dissipate heat using the pipe work. The controller can automatically shutdown the system to stop the cylinder from boiling.

Manual Controls - The TD9 Digital Controller is configured (e.g. setting of temperature differences required for the system to start/stop circulating - DeltaT) during installation to allow each system to achieve optimum performance. Once set-up no further user input is necessary. Settings can be changed and system tests run if required.

TD9 Displays & Indicators

LCD Display - In normal operation the controller will continually display the ‘Panel’ temperature and ‘Base’ temperature, as well as the ‘Tank’ temperature.

Solar Pump Indicator - The yellow indicator illuminates when the circulation pump is operating and your system is producing solar heated water.

Tank Hot Indicator - The red indicator illuminates when the water in the cylinder has reached the predefined temperature.

Other Features:

Memorises settings so no backup battery required.

In-built diagnostics and manual test functions.

Can be linked to a PC to record temperatures (additional interface module and software required).


Power Requirement: 240V 2A Max
Output Switching (Pump Relay): 240V AC 300W Inductive
Output Switching (Aux Relay): 240V AC 300W Inductive
Operating Temperature Range: 0° C to 50°C
Storage Temperature Range: -15° C to 60°C
Length: Display Unit: 127mm / Control Unit: 220mm
Width: Display Unit: 75mm / Control Unit: 145mm
Depth: Display Unit: 30mm / Control Unit: 50mm
Sensor: 3 x Digital Probes
Sensor Range: -20° C to 125°C
Sensor Accuracy: ± 1°C
Differential Temperature Adjust: 3° C to 28°C
“Tank Hot” Adjust: 0° C to 85°C
Differential Hysteresis: 2°C if DeltaT < 5°C Otherwise 3°C
Tank Hysteresis: 5°C
SMART Temperature Adjust: 0° C to 31°C

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