A variable flow valve comprising: a housing having an inlet port and a discharge port, and two or more control ports in fluid communication with the interior of the housing; a piston connected to a primary valve, which are both seated within the housing to open and close fluid communication between the inlet port and the discharge port; and a control port valve disposed to open and close at least one of the control ports access to a source of pressure change; characterized in that the housing and the piston intermesh to define a radially inner chamber and a radially outer chamber (58"), the inner chamber being in fluid communication with one of the control ports and the outer chamber (58") being in fluid communication with another of the control ports; the variable flow valve further including a position sensor having at least a component thereof connected to the primary valve to determine the position of the primary valve relative to the discharge port; wherein the position of the primary valve is used to communicate with the control port valve to hold the primary valve in a position where the discharge port is partially open, wherein the variable flow valve further comprises a pathway formed axially through the primary valve to connect the inlet port to the inner chamber for fluid communication therebetween, wherein the control port valve opens and closes fluid communication between the control port in fluid communication with the inner chamber and the control port in fluid communication with the outer chamber (58"), and wherein when the primary valve is in a closed position, the control port valve is open thereby providing fluid communication between the inner chamber and the outer chamber (58"), and when the primary valve is in a fully open position, the control port valve is closed thereby providing fluid communication between the outer chamber (58") and the source of pressure change without fluid communication between the inner chamber and the outer chamber (58"). a housing having an inlet port and a discharge port, and two or more control ports in fluid communication with the interior of the housing; a piston connected to a primary valve, which are both seated within the housing to open and close fluid communication between the inlet port and the discharge port; and a control port valve disposed to open and close at least one of the control ports access to a source of pressure change; characterized in that the housing and the piston intermesh to define a radially inner chamber and a radially outer chamber (58"), the inner chamber being in fluid communication with one of the control ports and the outer chamber (58") being in fluid communication with another of the control ports; the variable flow valve further including a position sensor having at least a component thereof connected to the primary valve to determine the position of the primary valve relative to the discharge port; wherein the position of the primary valve is used to communicate with the control port valve to hold the primary valve in a position where the discharge port is partially open, wherein the variable flow valve further comprises a pathway formed axially through the primary valve to connect the inlet port to the inner chamber for fluid communication therebetween, wherein the control port valve opens and closes fluid communication between the control port in fluid communication with the inner chamber and the control port in fluid communication with the outer chamber (58"), and wherein when the primary valve is in a closed position, the control port valve is open thereby providing fluid communication between the inner chamber and the outer chamber (58"), and when the primary valve is in a fully open position, the control port valve is closed thereby providing fluid communication between the outer chamber (58") and the source of pressure change without fluid communication between the inner chamber and the outer chamber (58").