Hi
We just bought a house with a gravity fed back boiler. The back boiler is a baxi bermuda 552.
The boiler is on the basement floor with the water tank above it on the ground floor.
the radiators from ground floor to top floor get hot when only hot water is selected on the programmer.
I thought there might be a valve that operates to stop the hot water expanding into the radiators to stop this kind of thing but I cannot find the valve.
I am only a novice so an experts opinion would be most welcome.
Regards in advance.
Peter