Radiators are hot with hot water

[Gareth45]

I've just bought a 3-floor house with a gas boiler on the ground floor and hot water tank on the middle floor. When I switch on the hot water at the timer panel, it works but it also heats up all the radiators above ground floor. I have to close them individually to stop this. The rads aren't just warm, they're proper hot so there must be good flow.

All the rads do work with the central heating also. However, I've noticed that the flow when the central heating is on is the opposite direction to when the radiators are heating with the hot water - i.e. I can tell by which pipe warms up first. So presumably the flow in the hot water circuit is then returning via the CH return pipe and going...somewhere...

Before I get a plumber in look at this, any ideas on what could be at fault to cause this?

Thanks
G

 

[Last Plumber]

Could be one of a number.
Need to know what type system e.g. S plan, Y plan, etc. Does it have motorized valves?
Can you send photo's of the controls/valves etc?