Myson Apolo 30s does this use 240v mains switching?

I have had to replace the main timer on my central heating system. I have gone for a siemens RWB7 electronic timer, the system will still not activate (boiler is fine). The only thing I can think that it would be is that I need to link the Live to one of the control circuit wires which is an option for 240v mains switching. When I moved into the house there was no boiler manual and cannot find one online.
Any ideas? Do not want to just link them and do something drastically wrong!