Turning on hot water heats upstairs radiators

Hi,

I have a QE2 boiler system. Everytime I turn on the hot water the upstairs radiators heat up (even though the heating is off), which I don't need on for the Summer. I have turned off the radiators. I have set the hot water timer to come on in the morning and the evening. But now that it is getting cooler in the mornings, I'd like the radiators to come on in the morning but not the evening. I don't want to have to keep turning the radiator valves on and off everyday so I'm wondering firstly is there actually something wrong with my boiler (is it normal that the hot water heats the upstairs radiators when the heating is off), or secondly is there a quicker way to turn off all radiators?

Any advise would be very much appreciated!!

Thanks.