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!

Marc A, October 2007

You need to link the timer feed (the brown wire)to the common terminal on the heating and hot water switch on the timer ie
heating n/o common n/c. hot water n/o common n/c.

allen, June 2008