The controller is simple to install, and can be configured in a variety of ways.  A typical basic installation will have 3 sensors, one in the collector panel, one at the top of the hot water tank and one at the bottom of the tank.  The controller compares the temperature of the collector panel with the bottom of the tank.  When the panel reaches 8 degrees hotter than the bottom of the tank the circulation pump is switched on.  It will remain on until the temperature differential falls to 4 degrees. (These settings can be adjusted if desired.)  All temperatures can be monitored from the controller display. 

The controller can be configured to switch a high temperature by-pass pump or valve, and has many other configurable program options.

Technical Specifications
Dimensions: 120mm x 120mm x 18mm
Power supply: AC230V±10%
Power consumption: <3W
Temp reading accuracy: ±2 degrees C
Range of collector temperature measurement: -10 to +220 degrees C
Range of tank temperature measurement: 0 to +110 degrees C
Suitable power of pump(s): up to 600W (3 pumps)
Suitable power of electrical heater: up to 1500W
Inputs: 2 x Pt1000 sensor (for collector)
           3 x NTC10K, B3950 sensor (for tank)
Outputs: 3 relays for circulation pumps or 3-way electromagnetic valves
             1 relay for electrical heater
Sensors included: 1 x Pt1000 sensor (for collector - can withstand up to 500°C)
                          2 x NTC10K sensor (for tank - can withstand up to 135°C)
(note: sensor cables can be extended up to ~50m using bell-wire)
Ambient operating temperature range: -10 to +50 degrees C
Water proof grade: IP40

Digital Controller - Advanced (SR868C8Q)
The advanced controller is as above, but having the following additional features:

• Thermal energy measuring
• High temperature by-pass function
• Holiday function (night cooling recirculation)
• Circulation pump variable speed control features

Sensors included: 2 x Pt1000 sensor (for collector - can withstand up to 500°C)
                          3 x NTC10K sensor (for tank - can withstand up to 135°C)

This controller is suitable for use with multiple panels in a dual-aspect configuration, with a single heat transfer circuit pipe (collector panels connected in series).