The Lochinvar & A.O. Smith 100187919 16" Natural Gas Burner Assembly Kit with #37 Orifice is a replacement combustion component designed for compatible Lochinvar and A.O. Smith gas water heaters. It works by regulating natural gas flow through its precision-sized orifice, supporting proper ignition and consistent flame production for efficient water heating. Ideal for residential and ... https://www.partshnc.com/100187919-lochinvar-ao-smith-nat-16-burner-assy-37-orf