The Lochinvar & A.O. Smith 100112614 Combined Controller is an OEM electronic control module designed to manage the operation of compatible natural gas commercial water heaters, including the A.O. Smith BTH 400A Series 104. It coordinates essential functions such as ignition sequencing, gas valve operation, temperature regulation, and system monitoring to ensure reliable heating perfo... https://www.partshnc.com/100112614-lochinvar-ao-smith-combined-controller