Steca TR A503 TTR

5 inputs, 3 outputs

  • For residential and commercial use
  • Ideal solution for double-circuit systems
  • Extremly low own consumption
  • Prepared for worldwide use
Steca TR A503 TTR
Steca TR A503 TTR technische Zeichnung
Steca TR A503 TTR
Steca TR A503 TTR technische Zeichnung


Along with the TR A501 T and TR A502 TT controllers, the TR A503 TTR is the third product in this series, which have a compact designer housing allowing universal use.

The TR A503 TTR extends the functionality of this series of devices by providing additional system monitoring functions. When used in conjunction with an external pressure sensor, the „System pressure monitoring“ controller function provides additional system monitoring. An additional controller output that can be individually customised for additional controller functions is also provided.

As with the other products in this series, a specially constructed switching power supply provides maximum efficiency and economic operation. This reduces own consumption to a minimum. The variable input voltage range allows universal use of the device worldwide.

The TR A503 TTR has two speed-controllable Triac outputs, that can also be configured as PWM outputs for controlling high-efficiency pumps and a relay switched output for additional controller functions. The equipment is rounded off by five inputs for recording temperature and pulses.

The integrated calorimetry system allows the acquisition of numerical information on the solar yields of the system. For more demanding requirements, this can of course be expanded using an external pulse encoder or an additional Grundfos Direct Sensors™.

Steca TR A503 TTR controller monitors and controls solar thermal systems with two differently oriented collector arrays and a maximum of two domestic hot water or buffer storage tanks. The third controller output can be individually customised for additional controller functions.

Eleven pre-programmed systems enable universal usage. The Steca TR A503 TTR also provides important monitoring and safety functions such as special error messages to quickly troubleshoot faults.

As with the other products in this series the new constructed electronic overloading control protects the TR A503 TTR against overloading and installation errors.


Technical drawing: Steca TR A503 TTR 5 inputs, 3 outputs

Product features

  • Compact, multipart designer casing
  • Installation versions: Solar pump stations, wall installation, mounting rails
  • Wave packet (Triac) and pulse width modulation (PWM) 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


  • Data logging to a MicroSD card
  • Heat quantity (Grundfos Direct Sensors™, pulse generator, determination)
  • Display showing CO2 savings
  • System pressure monitoring (e.g. Grundfos Direct Sensors™)
  • 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



  •  Steca TR A503 TTR certificate CE · pdf · 0.788 MB

Product data sheet

  •  Steca TR A503 TTR productdatasheet DE · pdf · 0,979 MB
  •  Steca TR A503 TTR productdatasheet EN · pdf · 0.979 MB
  •  Steca TR A503 TTR productdatasheet FR · pdf · 0,980 MB


  •  Steca TR A503 TTR manual DE · pdf · 4.323 MB
  •  Steca TR A503 TTR manual EN · pdf · 4.024 MB
  •  Steca TR A503 TTR manual ES · pdf · 4.005 MB
  •  Steca TR A503 TTR manual FR · pdf · 4.038 MB
  •  Steca TR A503 TTR manual IT · pdf · 4.321 MB
  •  Steca TR A503 TTR manual CZ · pdf · 4.071 MB
  •  Steca TR A503 TTR manual PL · pdf · 4.062 MB
  •  Steca TR A503 TTR manual SE · pdf · 3.927 MB

Product pics, technical drawings, etc.

  •  Steca TR A503 TTR product pic drawing · jpg, 300 DPI, high quality · 0.453 MB
  •  Steca TR A503 TTR product pic drawing · jpg, 72 DPI, web quality · 0.243 MB

Technical data

 TR A503 TTR
System voltage
115 V AC … 230 V AC, 50 Hz / 60 Hz
0.76 W
Temperature control class
Energy efficiency
1 %
Number of inputs
4 x temperature (Pt1000), 1 x temperature (Pt1000) or pulse
Additional inputs
1 x Grundfos Direct Sensors™ (temperature / flow rate), 1 x Grundfos Direct Sensors™ (temperature / pressure)
Number of outputs
2 x triac for speed control (R1, R2), max. 250 W (230 V) or PWM control signal for pump speed (PWM R1, PWM R2); 1 x switch output relay (R3), 2 A, 115 V AC … 230 V AC
Additional output
1 x potential-free switching output for the safety extra-low voltage
Hydraulic schemes
Ambient temperature
0 °C … +50 °C
Degree of protection
IP 22 / DIN 40050 [without front panel: IP 20]
Dimensions (X x Y x Z)
110 x 160 x 51 mm [0.00 x 0.00 x 0.00 inch]
370 g [0.00 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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