350,000 BTU/hr: 30-Plate Heat Exchanger, 1" MNPT ports, 4-1/4" x 12" Heat Exchanger Dimensions: 4-1/4" x 12" - 30 plates, with 1" mnpt ports 316L Stainless Steel - Copper brazed - Flow Rate: up to 35 GPM (max) Outdoor wood furnace and wood boiler heating Water-to-Water heating and cooling applications Domestic hot water heating