From the other thread...
View attachment 357717
Assuming Single Channel Hive...
Ideally with a 4 core and earth cable:
Connect L, N and E on the boiler, to Hive L, N and E.
Remove the red link wire on boiler terminals 1 and 2.
Connect boiler terminals 1 and 2, to Hive terminals 1 and 3 - the order doesn't matter.
Use the cable grips provided, to hold the flex.