A changeover valve includes a wall connection housing with at least one inlet channel and at least three outlet channels opening into a valve seat for receiving a valve upper part. The valve upper part has a base piece with at least three outlet openings connectable to a respective outlet channel via the valve seat. The valve upper part has at least one feed connected to the at least one inlet channel and connectable to at least one outlet opening via a control disc rotatable relative to a stationary inlet disc. The control disc engages with a spindle for rotating the control disc. The base piece has at least one positioning pin engaging into a positioning bore arranged in the valve seat. The valve seat has at least two positioning bores for engaging with the at least one positioning pin in different assembly positions of the valve upper part.