Vaillant Eco Tec Pro 24 Timer not working.

[Vaillant]

Hello,
the hot water works fine, and the clock works and ticks away, but the heating doesn't come on either with the timer or when we turn it to 'on'. The clock we have is the round dial with little pegs round the side to push in to set the timer. We've also turned it off and on, and at the mains as well.
Any ideas how to fix it, please?
Cheers.

 

[lame plumber]

call out a technician with the kit and know how to fix it. not being unhelpful but it could be more than just a faulty programmer

 

[Scott_D]

Got a room thermostat?

 

[Riley]

Did you fit the clock ??