Hi,

I am after a bit of advice about troubleshooting a central heating
problem. I am not an expert so some of my terminology may be incorrect.

From what I can make out, the system is fully pumped & vented. The
problem is that when the system is on 'Hot Water Only', 3 of my
downstairs radiators get very hot. The motorised valve head unit is
clearly showing that it has shut off the radiator circuit. Adjusting
the manual bypass valve does not seem to make any difference.

What could my problem be? I thought perhaps it could be that the valve
itself is not operating even though the motorised head is, or that the
pump maybe running in reverse?

Does anyone have any suggestions for how I might fix it?

Thanks in advance.

AJJ.