Another Hive

Ok so got the hive system yesterday for myself having previously installed at my sisters house with no issue, super straight forward took minutes. Assumed my setup would be similar, its not. Ive read all the other posts but none similar.

I have a Horstmann H27XL controller but I cant make sense of the wiring, currently doesnt seem to match the diagram for original install https://www.tlc-direct.co.uk/Technical/DataSheets/Horstmann/H27ZXL-Installation Instructions(S).pdf

I've started to label the wires but I'm not following. Though it looks wired on the attached pic there is nothing in what would be terminal 3.

Any help would be much appreciated .

Terminal 3 is only used in their examples 4 &5 - 2/3 port zone valve. Does your system have one?
Frank

1 is HW on, 4 is CH on, on your old programmer.
The wires from L to 2 and 2 to 5 are just links from the live supply to the commons on the 2 switches, discard them as this link is made internally on the hive.

N to N on hive
L to L on hive
1 to 3 on hive
4 to 4 on hive

Don't forget you will need to disconnect the old room thermostat cable from where it's wired back to and fit a link in it's place.