length 16.938 in; 9.750 1n. W; 9.313 in. H; burner mounting flange has 10 holes, 1/4-20unc-2b on a 5.000 in. Bolt circle; heat exchanger to heater connection threaded 2 1/2-8nps; 3 pipe nipples on top of exchanger, 2 connections threaded 3/4-16unf-2a, 1 connection clamp fit