Thermostat issue

[Echo the husky]

Thermo - White goes to valve brown
Thermo - Brown goes to red mains
Thermo - blue goes to black mains.

Valve - brown goes to thermo white
Valve - Blue goes to black mains.
Valve - earth to mains earth

This would be normal.

 

[Echo the husky]

I have a multi meter but not really used it. So I set it to AC Volts.

Yes. If it has several voltage ranges, set it to the highest.

when you say follow the flex from the drayton valve. do you mean the black power one which goes to joint box with mains and thermostat?

Yes. I missed your post about the joint box and it's wiring.

and put the prong in the blue and brown wiring block?
Thats the bit that scares me. was always told not to stick metal in electric sockets

Yes, connect one of the multimeter probes to the terminal where the valves blue wire is,
and put the second multimeter probe into the terminal where the brown wire is connected.

If it reads 240V the actuator is faulty.

Make sure the meter leads are in the correct sockets on the meter, 1 lead in COM and the other in the terminal marked V.

If you are at all unsure do not proceed.