Businesses in the tanks and boilers category supply, install, repair and maintain equipment used to store water or fuel and provide heating or hot water. Products may include domestic and commercial boilers, hot water cylinders, cold-water storage tanks, expansion vessels, oil tanks and associated pumps, controls, pipework and fittings. Some firms focus on particular types of system, such as gas, oil, electric or renewable heating, while others handle a broader range of equipment. Services can include assessing requirements, replacing or upgrading existing units, connecting equipment to heating and water systems, testing operation and diagnosing faults. Maintenance may involve cleaning, checking controls and safety devices, inspecting tanks for leaks or corrosion, and arranging repairs.