TIMKEN® How to determine the date of production/manufacture or age of TIMKEN® HVAC Systems. The date of production/manufacture or age of Alton® HVAC equipment can be determined from the serial number located on the data plate. Example serial number styles/formats found: Style 1: 78913 Back to Brand ListingStyle 1: 78913 Help keep this site FREE to the public. Please consider a single donation of $5, $10, $20, $50 or more… Or join some of our generous donors who provide $2 to $10 automatic monthly donations! Any amount will help and greatly appreciated to help us maintain this site for your use!