Honeywell V4073a Motorised Valve Spindle

[Transponderman]

I have a CH system with a Honeywell V4073a 3 port motorised valve. However the system has recently developed a fault where radiators heat up when hot water only is selected on the programmer, and therefore will not supply hot water only.
I have assumed that the Honeywell V4073a 3 port motorised valve is at fault and have bought a replacement head, but as I have now removed the old head I have discovered that the valve spindle has hardly any rotation on it.
Does anyone know how much the spindle on this type of valve should rotate? Do I need a complete new valve?

 

[D_Hailsham]

Does anyone know how much the spindle on this type of valve should rotate?

Don't panic. The spindle only rotates about 20°. Just make sure it is not stiff. If it is a small amount of WD40 or 3-in-1 may free it.

 

[Transponderman]

Thanks for your reply. I'm not sure of the exact number of degrees of rotation I have, but I recon I can rotate it about that. However, although I would not describe the spindle as stiff I do have resistance to the rotation, like pushing against rubber. Is this normal?

 

[scatmanjohn]

My bet is on the valve passing.(usually a swollen ball on this valve).

You can get a service kit for it or replace the whole body.

 

[Transponderman]

Thanks Guys, this has certainly helped and I think I know what I need now.