Please inform your electrician that the way to convert your 3-phase devices from 3-phase to single-phase is to: 

At the controller - link L1, L2 & L3 with 2.5mm sq. cable. Link the 2 neutrals (N) again with 4mm sq. cable (leave the existing link in place). Link U, V & W with 2.5mm sq. cable. All these links are best done on the top side of the connector strip.

At the heater, there are 3 existing links across terminals 2 & 3, 

remove 2 of them (leaving one in place) 

 and place them across terminals 4&5 and 5&6.

Connect 6mm sq. cable between the controller & the heater terminals. Live to V, neutral to right hand N in the controller. Live to 5 and N to 2 or 3 in the heater. Earths are obvious.

An alternative is to run 3 x 2.5mm sq. flexes between the heater & the controller and connect all 3 blues to the terminals 2&3 and the 3, browns to 4,5 & 6 respectively. The browns go to U, V & W and the 3 blues go to the R Hand N terminal in the controller. If this method is used LEAVE the 3 links across the heater terminals 2 & 3 and DO NOT link out U, V & W in the controller. Again the earths are obvious.

Connect supply to L2 and left hand N terminal. Make sure ALL connections are tight.

The thermostat needs mounting centrally above the the heater 40mm from the ceiling on the same wall that the heater is mounted on. If the plug needs removing to thread the cable through the wall and controller box, make a note of how it is connected - DO NOT TRUST the manual.

If you have any problems, give me a call on: 01909 566402, or email: AAsaunaman@gmail.com