A burner designed to supply gaseous fuel to an appliance originally designed to utilise another fuel. a. Firing Door Type - a conversion burner designed specifically for boiler or furnace firing door installation. b. Inshot Type - a conversion burner normally designed for boiler or furnace ash pit installation and fired in a horizontal position. c. Upshot Type - a conversion burner normally designed for boiler or furnace ash pit installation and fired in a vertical position at approximately grate level.