Brazed Plate Heat Exchanger, 5x12-10 Plate Water to Water Heat Exchanger 20,000 BTU 1" MPT B3-32-10 10 Plate Water to Water Heat Exchanger 5x12 BTU Rating: 20,000 (Commonly used for heating domestic water for 2 to 4 people) Btu Rating is based on 10 GPM; 180F water Stainless Steel 316L Radiant Flooring, Ice Melt, Domestic Hot Water High Quality, 40% Heavier then Competition