heating off but hot radiators

[AnonymousImport]

I'd be v grateful if someone could tell me why the radiators located in the top half of my flat heat up a great deal when the boiler heats the water, even though the heating is set to OFF. The other radiators are not as badly affected - they are on the same level or lower than the hot water tank. The heating is definitely set to OFF and I've put the thermostat down to 5'C just to be on the safe side. I've also checked each radiator individually and set them all to zero. But I still get my radiators heating up when the hot water comes on. I'd be very grateful for an explanation and also some advise as to how best to stop this happening. Thanks

 

[AnonymousImport]

there,s a control box on the pipework ,usually next to the hot water tank.this has a lever on ,which can be moved from hot water to central heating.it should sit in the middle of these.
this box may be faulty or you may have air in the system.