The Helios Fans WHR 4÷70÷40 is a warm water heater battery engineered for duct system applications, featuring flanges on both sides for a secure and stable installation. The casing is made from galvanized sheet steel, ensuring long-lasting protection against corrosion. The internal heat exchanger includes copper pipes and aluminium fins to provide high-efficiency heat transfer. Designed for demanding conditions, the unit supports a maximum operating temperature of 120 °C and a pressure capacity of up to 8 bar. The water connections are externally threaded, allowing for easy and reliable integration into hot water heating systems.