http://tinyurl.com/lpppsqz
20x20 Outdoor Furnace Heat Exchanger, 160,000 BTUProduct Review
Click on the link for more reviews
Units dimensions: 20.5"x22"x3.5" (not including manifold); Finned area: 20"x20"
Manifold Connections: 1" Sweat (1-1/8" OD copper); Tubes manufactured from 3/8" seamless copper
Casing: 18 gauge galvanized steel; Fin spacing: 12 fins per inch, Aluminum fins
Max operating temperature: 350 F; Fits furnace plenum sizes: 21x21, 21x23 and bigger
10 yr Warranty against manufacturer's defects