The Helios Fans WHR 4÷40÷20 is a warm water heater battery designed for duct system installation, featuring flanges on both sides for secure mounting. Its casing is made from galvanized sheet steel, providing durability and corrosion resistance. The heat exchanger includes copper pipes with aluminium fins to ensure effective heat transfer. This unit can operate at temperatures up to 120 °C and pressures up to 8 bar. The water connection pipes are equipped with external threads for easy and reliable integration into heating systems.