Hot rad when hot water only called for

[Kingbee]

Hello out there

I seem to have a problem with the seperation of hot water and radiator circuits. It is a recent issue as the system has worked fine for nearly 20 years.

When the time switch (danfoss 4033) asks for hot water only the only rad upstairs gets hot, but the rads downstairs remain cold. If the rad upstairs is shut down the rads downstairs get hot. This happens both when timed and manually selected.

I have changed the actuator (sunvic DM5651) to no avail and the spindle on the valve seems to spin freely although I haven't changed the body. Maybe I should do this?.

Any chance of some advice for the newbie. Cheers

 

[clf-gas]

Try changing the whole valve, possible has a worn body.

 

[Kingbee]

Ok. Thank you for your help, Craig. Thought that might be a solution but was trying to aviod the draining down bit!