SR81 Electronic Thermal Controller


The Intelligent Controller SR81 (Updated Version SR868C8) is used on split solar heating systems, it can show the temperature of water in the tank, the option of temperature difference, gives you frost protection and protection of memory and anti-bacteria.

Applications Capacity

Max. Number of collectors: 1.Max. Number of storage tanks: 1.
Max. Number of relays: 4.
Max. Number of sensors: 5.
Max. Number of visualization application system: 1.
FRT: 1 x Rotary vane type electron flow meter.


Technical Specifications

Size of Keypad: 120mm x 120mm x 18mm.
Size of Controller (4KW version): 218mm x165mm x55mm.
Power supply: AC100-240V, 50-60Hz.
Power consumption: < 2.5W.
Rated impulse voltage: 2.5KV.
Housing: Plastic ABS.
Protection type: IP41.
Mounting: Wall mounting.
Operation: 10 push buttons at the front cover.
Accuracy of temperature measuring: ± 0.1°C
Range of collector temperature measuring: -10°C ~220°C
Range of tank temperature measuring: 0°C ~110°C
Suitable power of pump: 3 pump possible to be connected.
Suitable power of HK (backup heating): 1pc (4KW version) <4KW—-10usd more.


5 sensors.
1pcs x Pt1000 sensor (≤500°C) for collector (silicon cable≤280°C).
4pcs x NTC10K, B3950 sensor (≤ 135°C) for tank, (PVC cable ≤105°C).
1 x FRT Rotary vane type electron flow meter (Flow meter and add-ons sold separately).


4 relays, for circulation pump and backup heating.
3 x Electromagnetic relay, Max. Current 2A.
HK relay (4KW version): 20A.
Ambient temperature: -10°C ~ 50°C.
Water proof grade: IP41.

In this package:

1 x SR81 controller.
1 x Accessory bag.
1 x User manual.
1 x PT1000 temperature sensor (φ6 x 50mm, cable length 1.5m).
1 x NTC10K temperature sensor (φ6 x 50mm, cable length 3m).
1 x 10A power cable.
Comes with 2 year warranty.


The unit must only be located in the dry interior rooms. Please separate routing of sensor wires and mains wires. Make sure the controller as well as the system is not exposed to strong electromagnetic fields.