A valve apparatus having a co-axial fluid inlet and outlet is disclosed. The valve apparatus comprises a housing having a generally tapering main cavity. The valve apparatus further comprises a first fluid inlet formed therein for receiving fluid from a source, a first fluid outlet for returning the fluid to the source, a second fluid outlet for discharging fluid from the housing and a second fluid inlet for receiving fluid and returning the fluid to the fluid source. A valve mechanism is slidingly mounted within a first valve chamber for controlling flow from the first fluid inlet to the second fluid outlet, the valve mechanism having a first position wherein a second valve chamber is in communication with the first valve chamber and the first fluid outlet, and a second position wherein a third valve chamber is in fluid communication with the first valve chamber and the second fluid outlet.