No hot water, but central heating working

[jxm]

If you turn the power off to the ch system the valve should close & the lever on the 3 port should have resistance on it to ope the valve manually. If its all slack then it may be seized in the heating posistion!

Just to be clear if the valve is "closed" does that mean it's going to CH or the water heater?

 

[kay-jay]

normal (un energised) position is open to hot water closed to heating.

the lever not moving the motor/no resistance may be because you are calling for heat? please confirm that when you are moving the lever the programmer is set to off for both heating and water. if there is still no resistance on the lever then the motor is goosed.

 

[jxm]

The plumber has just fixed it. It was the 3 way valve, totally
apparently, including the level.