Domestic Hot Water (Details) FP508 - W/W Flat Plate Heat Exchanger 4 - 1" Brass Union 2 - 3/4" to 1" Brass Reducer Bushing 2 - 3/4" M. Adapt. x 3/4" Fw. Sw. 2 - 1" x 1" M.P.T. Male Coupling Adapt.