The CV300 is a redundant combination control similar to the CV200 with an optional regulated or unregulated pilot. A regulated pilot can help eliminate expensive service calls in areas of gas pressure fluctuations. Using the combination control helps reduce the cost of installation and eliminates the need to stock a separate pilot regulator. Another advantage of the control is its greater regulation range—up to 80,000 Btu/hr. Applications for the control include gas fireplaces, commercial cooking appliances, and patio heaters. The unit combines two electrical shutoff valves with a pressure regulator. The valves are normally closed solenoid valves. When the solenoids are energized, the valves open and gas flows from the inlet through the upstream valve opening to the regulator. Gas then passes through the downstream valve to the outlet and the appliance. Located between the upstream valve and the downstream valve, the regulator controls the outlet pressure. There are three key functions in the regulator section of the valve. A diaphragm senses changes in outlet pressure with reference to atmospheric pressure. The spring provides a standard to which the controlled pressure is referred, and a variable restrictor, or poppet valve, moves in accordance with the diaphragm/spring assembly to maintain regulated outlet pressure. The gas flow stays on the side of the diaphragm opposite the spring. The spring side of the diaphragm is open to the atmosphere by a vent in the lid. Changes in inlet gas pressure or downstream flow requirements (which can change outlet pressure) are sensed by the diaphragm/spring assembly. The sensing action causes movement of the variable restrictor valve so that outlet pressure is kept constant.