This annual check also identifies any defects which require remedial work. Some gas suppliers may offer a free gas safety check if you are of pensionable age, disabled or chronically sick or if you have children under 5 years old. A gas safety check assesses the basic safety of a gas appliance, whereas a service will involve taking the appliance apart to assess the physical condition of the appliance, the installation pipework, air vents and any flues. Servicing will generally also include performance tests and should be carried out in accordance with manufacturer's instructions. If your gas fire is not working properly or you notice it is burning with a lazy yellow flame instead of a crisp blue flame, and/or can see black marks or soot stains on or around your fire - you need to call an engineer as soon as possible. If the engineer identifies a problem with your gas fire he or she will follow the Gas Industry Unsafe Situations Procedure when assessing the risks of an unsafe gas appliance and will leave you with a report which explains what checks they have completed. A typical gas fire safety check cost is around