Steca TR A502 TT U

5 inputs, 2 outputs

  • For residential and commercial use
  • Ideal solution for double-circuit systems
  • Extremly low own consumption
  • Prepared for worldwide use
Steca TR A502 TT U
Steca TR A502 TT U technische Zeichnung
Steca TR A502 TT U
Steca TR A502 TT U technische Zeichnung


The Steca TR A502 TT U controller is an ideal solution for all double-circuit systems. It monitors and controls solar thermal systems with up to two differently aligned collector arrays or a maximum of two domestic hot water or buffer storage tanks.

The Steca TR A502 TT U is also distinguished by the compact casing, which is typical for this series of devices. It can be superbly integrated into solar stations, but of course it can also be installed on walls or top-hat rails. The variable input voltage range allows universal use of the device worldwide.

The solar controller has five inputs for acquisition of temperature and pulse information and two outputs. These can also be used for controlling (0-10 V) high-efficiency pumps. The device is equipped with an additional alarm output. The operating states are visualized on an animated, clearly arranged display.

Together with an external pulse encoder, the integrated calorimetry system allows the acquisition of numerical information on the solar yields of the system.

The controller can be used in a wide range of applications and is exceptionally easy to configure and operate: Eleven system configurations are pre-programmed. The inputs and outputs are already defined and you can see what is connected at a glance. Installers only need to set the boundary parameters. The system setting ”0.1” allows free selection of the controller functions to suit the system type and operating requirements. The ability to be mounted on a wall or top-hat rail emphasizes the flexible range of uses for the device.

The specially constructed switching power supply in the Steca TR A502 TT U, which is used in all controllers of this series, ensures the maximum possible efficiency and economic operation. The new electronic load control system protects the device from overloading and installation errors.

This ensures long-term, safe and reliable operation of the entire solar system.

The Steca TR A502 TT U also provides important system monitoring and safety functions. This ensures long-term, safe and reliable operation of the entire solar system. For rapid correction of system malfunctions special error displays are shown.


Technical drawing: Steca TR A502 TT U 5 inputs, 2 outputs

Product features

  • Compact, multipart designer casing
  • Installation versions: Solar pump stations, wall installation, mounting rails
  • Wave packet (Triac) and 1-10 V control signal ensure electronic RPM control
  • High level of operational safety through fault diagnosis
  • Hours-of-operation logger
  • Software update possible
  • Daily pump start
  • Screw terminals allow universal and rapid installation
  • Low power consumption thanks to universal and widerange switched-mode power supply
  • Variable input voltage range for worldwide controller deployment
  • Electronic overloading control and protection


  • Multifunction graphical LC display with backlighting
  • Animated representation of the systems and operating states


  • Non-verbal menu navigation
  • Manual switch for manual, auto, off


  • Heat quantity (pulse generator, determination)
  • Display showing CO2 savings
  • Drain back
  • Reduction of stagnation phases
  • Active cooling (e.g. to avoid stagnation)
  • Holiday (storage tank recooling)
  • Circulation (controlled by temperature / time)
  • Back-up heating
  • Solid fuel boiler
  • Storage tank quick charge
  • Thermostat
  • Differential thermostat
  • Interval / tube collector
  • Anti-freeze
  • Display storage tank top
  • Alarm output


Product data sheet

  •  Steca TR A502 TT U productdatasheet DE · pdf · 0,989 MB
  •  Steca TR A502 TT U productdatasheet EN · pdf · 0.989 MB
  •  Steca TR A502 TT U productdatasheet FR · pdf · 0,990 MB


  •  Steca TR A502 TT U manual EN · pdf · 1.914 MB

Product pics, technical drawings, etc.

  •  Steca TR A502 TT U product pic drawing · jpg, 300 DPI, high quality · 0.550 MB
  •  Steca TR A502 TT U product pic drawing · jpg, 72 DPI, web quality · 0.291 MB

Technical data

 TR A502 TT U
System voltage
115 V AC … 230 V AC, 50 Hz / 60 Hz
0.76 W [0.001 HP]
Temperature control class
Energy efficiency
1 %
Number of inputs
4 x temperature (Pt1000), 1 x temperature (Pt1000) or pulse
Number of outputs
2 x triac for speed control (R1, R2), max. 130 W /0.17 HP (120 V AC) or 0-10 V control signal for pump speed (0-10 V R1, 0-10 V R2) / PWM control signal on request
Additional output
1 x potential-free switching output for the safety extra-low voltage
Hydraulic schemes
Ambient temperature
0 °C [+32 °F] … +50 °C [+122 °F]
Degree of protection
IP 22 / DIN 40050 [without front panel: IP 20]
Dimensions (X x Y x Z)
110 x 160 x 51 mm [4.33 x 6.30 x 2.01 inch]
350 g [12.35 oz]
Solar system, collector, single-family house

Solar thermal systems

Solar thermal systems convert solar irradiation into heat so that it can be used to heat domestic hot water or for back-up heating.more
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