no central heating but hot water fine ravenheat csi85 b (t)

[wian]

Hello everyone
I have a ravenheat csi85 b (t) hot water works great but no central heating.
No external thermostats or clock. But when I press internal clock (tm6192) red light comes on but nothing after that. Have change the clock still the same checked the diverter valve that's fine changed the thermistors one of which was the clip type but still the same. Is their any electrical test I could do to find out what the problem is or better still does anybody know any answers.

P.S I know its a ravenheat but don't be a hater

 

[wian]

Sorry me again just me again with update I got the new clock off eBay I know it was supposed to be new just tested continuity between 3 and 5 and got nothing. So tested the two wires for 3 and 5 and the boiler fired up so it is the clock at fault then can someone just confirm this before I go and buy another one from proper shop many thanks