Worcester Bosch TDS 10 is another simple but effective controller without pump speed control.
Though limited by minimal functionality it is straight forward to operate and ?end user? friendly.
There is a 3 position switch on the left which allows operation in Manual ON or OFF but should be left in the central position in AUTO.
It is based on the Steca TR 0301 manufactured in Germany.
However this controller is susceptible to relay failure and the sensors giving erratic readings which causes the relay to operated too frequently.
Link to manufacturer?s instructions: