Having just moved into this house I have not fully had time to explore
the central heating system yet, so details might be a little bit
brief..

But hopefully someone may have had this problem before!

Normal (not combi) potterton bolier in the kitchen that looks a good
10-15 years old, with hot water tank upstairs.

Timer is one of the really old fashined ones with the red/blue pins
for on/off on the dial, and thermostat in the living room.

Problem..

Even with thermostat down as far as it will go, radiators remain hot,
only way to cool them down is to turn off the central heating fully.
Have not yet confirmed whether they cool down if we turn c/h off but
leave water on... thats next on my list!

(When you turn the thermostat up you can hear the pump start, but the
rads are hot anyway)

Given that the rads remain hot, even when the pump is not pumping,
could it be a faulty pump valve allowing hot water to circulate via
convection, or is likely to be more serious?

anyone else had this weird problem?