ok sorted this wire problem out, i missed the hot water sat (link) to the cent heating so now the cent heating works on its own as it should. please note this glowworm boiler has replaced the myson boiler which has been in the house since i moved in 25 years ago. it never had a room thermostat (trv,s on all rads) as for the gas engineer he did a great job of fitting the boiler and flue etc he just had the problem of the wiring to the actuator. i have been in contact with him and he was organising the solution to the actuator prob.