warm start-vailliant turbo boiler

[BJS]

Not sure if this is in right section but the WARM START on my boiler is not working.
The green indicatot light is lit OK but the boiler does not switch in at all as it should do when the boiler temerature falls below 40. So far the THERMISTAT and the AQUASENSOR have been changed with no result.
Any helpful plumbers out there with any ideas.

[Hard@it]

Save yourself a lot of cash in the long run - pay Vaillant for a years maintenance, their man will have it right in an hour.
It is about �100 for a year but if you count all the money you will hand out to supposed plumber type experts you will soon see. This covers all parts and labour. Cheers Hard@it

[gasman]

Did you change the potentiometer at the same time as the thermistor they often go hand in hand when servicing . But it is hard to say what is wrong without performing a fault finding exercise. Are you sure that the wall thermostat is calling for heat and any timers/programmers are also calling that maybe overiding the boiler & stop it from firing ?