A valve comprising: - a body having first and second and third connectors, forming a coplanar, T-shaped configuration, at least said first and second connectors being adapted for connection to a respective element of a fluid circulation system; and - a ball valve member enclosed internally within the body and having first second and third apertures (31, 32, 44) forming a corresponding coplanar, T-shaped configuration said ball valve member being arranged for selective rotation of the first, second and third apertures in the shared plane of the first, second and third connectors between a range of positions comprising: - a first open position allowing fluid communication between the first connector and the third connector, but not the second connector; - a second open position, allowing fluid communication between the second connector and the third connector, but not the first connector; - a third open position, allowing fluid communication between all of the first connector, the second connector, and the third connector; and - a closed position, allowing fluid communication between the first connector and the second connector, but not the third connector; and the valve (109 being characterised in that: - the body further comprises a fourth connector; and - the ball valve member further comprises a conduit comprising a channel formed in the outer surface of the ball valve member and extending to one of said first second or third apertures from an entry point on the surface of the ball valve member located outside the shared plane of the first, second and third apertures, to permit fluid communication between said fourth connector and at least two of said first, second and third connectors in each of said range of positions of the ball valve member. - a body having first and second and third connectors, forming a coplanar, T-shaped configuration, at least said first and second connectors being adapted for connection to a respective element of a fluid circulation system; and - a ball valve member enclosed internally within the body and having first second and third apertures (31, 32, 44) forming a corresponding coplanar, T-shaped configuration said ball valve member being arranged for selective rotation of the first, second and third apertures in the shared plane of the first, second and third connectors between a range of positions comprising: - a first open position allowing fluid communication between the first connector and the third connector, but not the second connector; - a second open position, allowing fluid communication between the second connector and the third connector, but not the first connector; - a third open position, allowing fluid communication between all of the first connector, the second connector, and the third connector; and - a closed position, allowing fluid communication between the first connector and the second connector, but not the third connector; - a first open position allowing fluid communication between the first connector and the third connector, but not the second connector; - a second open position, allowing fluid communication between the second connector and the third connector, but not the first connector; - a third open position, allowing fluid communication between all of the first connector, the second connector, and the third connector; and - a closed position, allowing fluid communication between the first connector and the second connector, but not the third connector; - the body further comprises a fourth connector; and - the ball valve member further comprises a conduit comprising a channel formed in the outer surface of the ball valve member and extending to one of said first second or third apertures from an entry point on the surface of the ball valve member located outside the shared plane of the first, second and third apertures, to permit fluid communication between said fourth connector and at least two of said first, second and third connectors in each of said range of positions of the ball valve member.