York plate and frame heat exchanger, serial number 10554237, 2-1/2" threaded inlets and discharge with 2" Tri-Clover fitting adapters, 87 each 12" wide x 43" tall plates, two zones with regenerative block, 44 plates in zone one and 43 plates in zone two, total surface area of 312 square feet, 40 extra plates, all stainless steel construction.