The Helios Fans WHR 355 is a compact water heater battery designed for connection to circular ducting. It has a galvanized steel casing that provides durability and corrosion resistance. The spigots on both ends include double lip rubber seals to ensure a secure fit with standard nominal ducts. The heating elements are made from copper with aluminium fins, delivering efficient heat transfer. The unit operates at a maximum temperature of 100 °C and can withstand pressures up to 8 bar. Two inspection caps on the water connection side simplify installation and maintenance.