Capable of delivering up to 150° F leaving hot water, WaterFurnace’s 5 Series 504W11 with OptiHeat vapor injection technology is ideal for high-temperature applications, such as baseboard radiator systems, underfloor radiant applications, overfloor radiant applications and fan coils. This system has been designed specifically to meet higher temperature requirements, and its compact size allows for installation in confined spaces. The additional heat exchanger in it diverts excess heat and reinjects it into the system.