A certified Gas Safe registered engineer will check and test a single gas device, such as a boiler, gas cooker, or gas fire, and issue a Gas Safety Certificate for that equipment.  Gas leaks, adequate ventilation, safe operation, and adherence to safety rules are all examined by the engineer.  The appliance is given the CP12 certificate, which attests to its safety, provided it satisfies all necessary requirements.  In order to guarantee safety, both homeowners and landlords who rent out houses must have this certificate.  Frequent inspections preserve efficiency while reducing the risk of carbon monoxide poisoning, gas leaks, and expensive repairs.