Runaway heating

[csauk]

Hi. I have a recently installed open-vented, fully pumped Y-plan heating and hot-water system. Yesterday the heating wouldn't switch off. I could hear the microswitch in the room stat click when it was turned down but the neon stayed on. I've noticed also that when the heating is off at the programmer the neon has always flickered faintly when the room temp drops below the set temp. Should it do that? The stat is a ty 92 A1 from Grasslin UK. The boiler is a Vaillant emax pro. Today all seems normal apart from the flicker. Any advice gratefully received.
Cheers

 

[Agile]

Is this a DIY job or are you a CORGi registered heating installer?

 

[ChrisR]

Sounds like it has been wired up incorrectly. Can happen that the system works for a while but then damage occurs from mains being where it shouldn't be.

 

[csauk]

Is this a DIY job or are you a CORGi registered heating installer?

I installed all the pipework and rads and a Corgi reg plumber installed the boiler and wired everything up but I have lost confidence in him and was hoping for some advice from an alternative source.