Note: If your installation includes a buffer tank, two heating zones or a secondary circulation pump, consider the cable runs back to the Passiv Programmer's wiring-centre where these connections can be easily be accommodated.
Additionally, if the green RS485 cable runs are longer than 100m, instead of using 1 twisted pair screened cable use 2 twisted pair screened cable, as connecting the GND, A & B between the Grant heat pump and the Programmer will require 3 cores.