Commercial LPG and Diesel-Fired Heaters A.O. Smith Cyclone Xi BTH-120 LPG Water Heater A.O. Smith Cyclone Xi BTH-250 LPG Water Heater A.O. Smith Master-Fit BTR-180 LPG Water Heater A.O. Smith Master-Fit BTR-198 LPG Water Heater A.O. Smith COF Oil-Fired Water Heater Series