SOLAR THX specification
SOLAR THX is an entry level 'fit and forget' pump controller using the difference in temperature principle to start and stop a circulating pump in a solar powered water heating system. It is an ideal replacement for old field units which may be operating erratically and generally uses the same sensors.  

SOLAR THX works by continuously monitoring the solar collector and water tank until a preset temperature difference occurs. The pump then operates until both temperatures equalise. Pump 'on' is approx 5C to 6C difference, 'off' is approx 2.5C to 3C. Visual indication of pump is by red coloured LED

SOLAR THX can be free standing or permanently connected at a convenient location anywhere in the house. It is mains powered and requires no user intervention for reliable and continuous operation.  

SOLAR THX may also be used as a basic alarm in traditional thermo-syphon (gravity) systems by highlighting pipe blockages or circulation inefficiencies

SOLAR THX uses all analogue circuitry with suppression included on switched circuits. It is constructed on a fibreglass PCB using top quality branded components and mounted in an ABS enclosure.

SOLAR THX uses a pair of (thermistor) sensors, double rated electrolytics and a massive 12 Amp rated relay for extra, extra long life. Low current consumption means the annual running cost is about 80p - much less than ½ pint of beer!


Differential Set-points:                     Preset: 5/6 degrees on 2/3 degrees off
                                                    Not adjustable.
Supply indication:                           Green LED.
Pump operation indicator:                Red    LED.
Manual pump operation:                  None.
Sensors:                                        Thermistor(s) 20k (Note: supplied seperately)
Isolation:                                        CE approved transformer  
Warranty:                                       1 years parts replacement


For inside mounting only, for best results mount the product in a stable thermal environment free of draughts eg under-stairs cupboards. This product is designed to switch 230 ac central heating type pumps up to 250 Watts
Try to keep sensor cable runs away from 50Hz mains wiring

External Dimensions                  160mm x 97mm x 55mm ( 6x4x2")
Weight                                      0.382kg (12oz)
Colour                                       Black (may vary)
Enclosure                                  ABS plastic spatter finish
Mounting                                   Wall or flush - installer to decide
Cable entry                                Through base or walls - installer located


Supply                                      200 - 240 V ac 50-60 Hz
Consumption Quiescent             1.2W
Consumption Max                      2.1W
Operating Temperature               15 - 25C Keep in stable environment
Temperature rise                        4C
Switching contacts                     SPCO 12 Amps at 240Vac fused (AC1)
Fuse                                         20 mm 5 Amp (Internal)


Mains                                       Three terminal 'E L N' screw block
Pump                                        Four terminal 'L1 L2 N E' screw block
Tank sensor                              Two terminal 'a - k' screw block
Panel sensor                             Two terminal 'a - k' screw block
A differential Temperature switch for solar water heating systems

Sensors are thermistor 10mm dia. Stainless Steel suitable for contact or direct immersion sensing using our T adaptor kit. (see elsewhere for pics.)
Standard Sensor leads are 3m long with ferrule termination, longer leads may be ordered for a per metre price increase.
Sensors are suitable for all fluids compatibile with Stainless Steel and processes other than DHW.