Businesses in boiler servicing and installation inspect, maintain, repair and fit boilers used for domestic or commercial heating and hot water. A service commonly includes checking the appliance and its controls, inspecting accessible flues and ventilation, cleaning or adjusting components where needed, and testing operation and safety. Engineers may identify faults, replace worn parts and advise on repairs or maintenance, but a service does not necessarily include every repair or guarantee that a boiler will remain fault-free. Installation work can involve replacing an existing boiler or fitting one as part of a new heating system. This may include assessing the property's heating and hot-water requirements, installing a combi, system or conventional boiler, connecting pipework and controls, and commissioning the system. Some businesses also install or replace radiators, thermostats and associated heating components.