with efficiencies up to 87% the casco bay is our most efficient boiler and offers you a smart step in the battle against rising fuel cost. It achieves these efficiencies by circulating the flue gases through the boiler 3 times. The longer the flue gases stay in your boiler the higher the efficiency achieved. The casco bay offers you the versatility of either a direct vent or a chimney vent application. It offers you the most effective and efficient way to heat your home and your domestic hot water. the attractive cabinetry with its contemporary lines and designer look conceals the burner, piping and the controls. Your service technician will love this boiler for its serviceability and its versatility. The casco bay features a swing open door for thorough cleaning of every inch of heating surface of your boiler.