HW 2 port not opening when calling for heat

[henrymerrington]

i have a 2 port honeywell valve that does not open or fire boiler when programmer is calling and stat is. the valve moves manually and ive changed the head of the valve could it be a programmer fault?

 

[Puddle]

Well it could be the programmer or cylinder thermostat or just a loose wire connection you will have to follow the power supply and find break

 

[Bernie2]

Trace wiring, turn off electricity and using a multi meter check continuity.

If its suspected to be only the 2 port valve. Turn off electricity, remove head cover, trace two wires from motor and check resistance if its infinity open circuit, get new motor, fit and test.

 

[henrymerrington]

i changed the head but still no joy.

 

[GroundControl]

you say you've changed the head but no joy !!
1)have you checked that there is 230V to the head terminals ? that would be the brown and blue wires on the black cable from the head or across the two orange wires internally ?
2) does the motor operate ?
3) does the valve open ?
4) is there a voltage to the grey or orange wire ? in the main black cable