The Combined Valve and Ignition (CVI) system has  been developed for application in gas fired domestic central heating boilers, combi boilers and warm air furnaces or water heater appliances with an automatic ignition system.For this system, the S4565, S4575 and S4585 ignition controls are used in conjunction with the VK41.. series gas controls to provide and optimised safety sub-system for programmed safe light up and flame supervision of the main burner of the applianceThe combined system then provides programmed safe light up, flame supervision and regulation of gas flow to the main burner and/or pilot burner of the appliance.