Posted By Graham Findlay According to HSG 55 (Health and Safety in Kitchens and Food Preparation Areas), "gas appliances should be regularly serviced by a competent gas service engineer. The appliance manufacturers instructions should say what the user should do in this connection, and how often. Always follow the manufacturers instructions." We operate a large number of kitchens containing gas equipment, and they are all serviced annually. Its easier to manage it in this way. Graham Findlay