A.O. Smith Water Products Co. has introduced the ProMax® XL circulating loop heat exchanger. The unit is designed for installation with ProMax SL (Side Loop) residential gas water heaters to provide domestic hot water plus an isolated source of hot water for radiant floor heating, fan coil heating, hydronic air handling units and other closed-loop applications. Offered in 28,000 or 52,000 Btu output models (at 140