Saturday, April 29, 2023

The New Technology for Solar Hot Water, the STECA Controller and Pump and Sensors

 The STECA Controller is the newer technology and offers benefits to both the system owner, and the servicing contractor.

The STECA is the brains of the Hot Water Solar, The 120V Grundfos pump is the heart of the system.    The brain need information input, and that comes by 3 new temperature sensors.

These components describe the "120V Conversion" STECA upgrade.

1) STECA Controller

2) Grundfos Pump (or it might be a 120V TACO pump)

3) Unique Ohm Thermistors (aka temperature sensors).

Using the programmability of the Smart Controller (your solar company will set it up for you), and the Three Temperatures that get displayed, it is easy to see exactly what the system thinks is happening, and the decisions made on how to operate at optimal efficiency. 

ALL the other hot water solar controllers have NO DIGITAL DISPLAY and no temperature outputs.   You have no idea what it thinks the system temperatures are, and no idea of how it is trying to control the system.   All the others are "Dumb Systems" that require guess work to fix problems, and guess work can be expensive!

The STECA also has a "Vacation Mode" which prevents the system from overheating when you are away for 3 or more days


Steca TR 0301 U

3 inputs, 1 output

  • Compact, multipart designer casing
  • Graphical LC display with backlighting
  • Animated representation of the systems and operating states
  • Non-verbal menu navigation

Steca TR0301 U picture 3D.jpg


The Steca TR 0301 U controller was specially developed for the North American market based on the Steca TR 0301 basic controller. With its special certification (ETL label) from a Nationally Recognized Testing Laboratory (NRTL) in the US, the controller meets the safety standards and minimum requirements of the North American market.

A feature of the Steca TR 0301 series of controllers is the animated graphic display, which offers a complete visualisation of the solar energy system's operating status and solar circuit.

The clearly arranged display ensures easy operation using pictograms. The controller was jointly designed with an internationally renowned design centre. The controller is used for monitoring and controlling solar thermal systems with one collector array and one storage tank. In addition, the controller performs important system monitoring and safety functions to ensure safe and long-lasting operation of the entire system. The numerous additional functions of the Steca TR 0301 U also include a maximum storage tank temperature function, a tube collector function, an anti-freeze function, a holiday and storage recool function as well as a choice of temperature indications in either degrees Celsius (°C) or Fahrenheit (°F). The operational safety of the system is supported by a sophisticated fault diagnosis. The multi-coloured LCD backlighting ensures quick and safe location of occurring errors and facilitates quick troubleshooting.

The Steca TR 0301 U controller is supplied with a pre-fitted US mains connection cable and a preinstalled, pluggable pump output.


Technical drawing: Steca TR 0301 U 3 inputs, 1 output

Product features

  • Compact, multipart designer casing
  • Maximum storage tank temperature
  • High level of operational safety through fault diagnosis
  • Temperature display °C / °F
  • Collector overtemperature disconnection
  • Spring clamp terminals allow rapid and easy installation


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


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


  • Holiday (storage tank recooling)
  • Interval / tube collector
  • Anti-freeze
  • Display storage tank top


Product data sheet

  •  Steca TR 0301 U productdatasheet DE · pdf · 1,015 MB
  •  Steca TR 0301 U productdatasheet EN · pdf · 1.015 MB
  •  Steca TR 0301 U productdatasheet FR · pdf · 1,015 MB


  •  Steca TR 0301 U manual EN · pdf · 2.190 MB

Product pics, technical drawings, etc.

  •  Steca TR 0301 U product pic 3D · jpg, 300 DPI, high quality · 0.687 MB
  •  Steca TR 0301 U product pic 3D · jpg, 72 DPI, web quality · 0.223 MB
  •  Steca TR 0301 U product pic · jpg, 300 DPI, high quality · 0.512 MB
  •  Steca TR 0301 U product pic · jpg, 72 DPI, web quality · 0.177 MB
  •  Steca TR 0301 U product pic drawing · jpg, 300 DPI, high quality · 0.719 MB
  •  Steca TR 0301 U product pic drawing · jpg, 72 DPI, web quality · 0.343 MB

Technical data

 TR 0301 U

System voltage
120 V AC, 60 Hz
System voltage optional
240 V AC, 60 Hz
1.07 W [0.001 HP]
Temperature control class
Energy efficiency
1 %
Number of inputs
3 x temperature (Pt1000)
Number of outputs
1 x switch output relay (R1), max. 400 W / 0.5 HP (120 V AC) or 800 W / 1 HP (240 V AC)
Line cord
75 inch, 3 x 18 AWG at 221 °F
Turn-on temperature difference
16 F
Turn-off temperature difference
8 F
Ambient temperature
0 °C [+32 °F] … +45 °C [+113 °F]
Degree of protection
IP 20 / DIN 40050
Dimensions (X x Y x Z)
160 x 157 x 47 mm [6.30 x 6.18 x 1.85 inch]
350 g [12.35 oz]
Temperature sensors 2 x Pt1000
1.5 m [59 inch] silicone cable without bushing (measuring range up to +180 °C [+356 °F])

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