The Helios Fans WHR 400 is a compact water heater battery designed for integration with circular duct systems. It features a durable galvanized steel casing, and both ends are equipped with spigots that include double lip rubber seals to ensure a secure and airtight fit with standard nominal ducts. The internal heating elements are constructed from copper and paired with aluminium fins to deliver efficient and consistent heat transfer. This unit is rated for a maximum operating temperature of 100 °C and a pressure of up to 8 bar. For straightforward installation and maintenance, two inspection caps are located on the water connection side