Temperature differential controller LTDC-V4, remote control

• For medium solar systems and solid fuel boilers.
• For standard and high-efficiency recirculation pumps with PWM signal.
• With 6 inputs and 3 outputs.

Varied, networked and user-friendly. Thanks to the crystal-clear user prompting, all types of solar system can be operated intuitively – from small to complex.
The plain-text operation guides the user with easily understandable, context-dependent help texts through commissioning, setting and evaluation and provides simply navigation through the well-organised menu – in up to 20 languages integrated in the controller, freely selectable in the menu.
When used for the first time, a commissioning wizard guides the user step by step through all the required settings for rapid and uncomplicated commissioning. The high-contrast, illuminated display indicates the system status with data and animated system hydraulics. Statistics such as the system’s heat yield can be called up at the push of a button, in graphic or text form.
Each TDC model has various, freely selectable system layouts depending on the controller size, ranging from simple solar systems to complex systems with up to two collector fields and four reservoirs. Activating additional functions by means of free relay allows these basic systems to be customised very easily.


• Time- and temperature-controlled thermostat function
• Battery-buffered real-time clock RTC
• Legionella switching via solar
• Legionella switching by means of additional heating
• Cooling function
• System protection
• Collector protection
• Reservoir protection
• Frost protection programme
• Back cooling
• Start logic for vacuum tube collectors
• Control programme for self-draining systems (Drain-Back)
• Data storage with statistics and graphical evaluation
• Fault memory and evaluation with date and time
• Menu blocker

For larger solar systems.
Technical data:
• Sensor inputs Pt1000: 6
• Relay outputs 230V: 3
• Of which for rotational speed control for standard pumps: 2
• Outputs 0..10 V or PWM signal: 2
• VFS/RPS sensors: 2
• Number of applications: 36+
• LEDs red/green to display operating states: 1
• Simple heat measuring: yes
• Heat metering via Grundfos direct sensor (VFS): yes
• Pressure monitoring via Grundfos direct sensor (RPS): yes
• Ethernet connection with PC control software optional: yes
• Datalogging on SD card: no
• Sensor not included in delivery

SOREL Connect – monitoring, evaluation, remote control
SOREL Connect is the new plug & play system that requires no special network knowledge. The controllers can communicate with one another via CAN bus, or be connected to local networks or the Internet via Ethernet.

Sorel Connect only possible
in conjunction with Sorel datalogger.