Radiators getting warm when off

[legless]

Hi
I have condenser boiler central heating system. My radiators are off at the moment as it is summer and the hot water is on alone. 2 of my radiators are getting warm and they should be cold. Anybody got any ideas what is wrong?
Regards Peter

 

[buck51]

were are the rads in house and in relation to the boiler?
Is one of them the bathroom?

 

[legless]

One is the kitchen radiator where the boiler is. The other is near to the water cylinder and pump

 

[buck51]

It sounds like it was a gravity hot water system at one time, and it was common practice to connect the bathroom rad into it
can you trace the pipework out?
why not just shut the rad valves off in summer if you dont want them on it will be cheaper than replumbing them