Test chambers designed and built to guarantee the necessary conditions for testing the performance of indirectly heated (closed) storage water heaters up to 2,000 l capacity that are suitable for connection to a water supply at a pressure between 0.05Mpa and 1.0Mpa (0.5 and 10 bar) and are fitted with control and safety devices designed to prevent the operating temperature of the stored water from exceeding 95°C.