Hvac Serial Number Cheat Sheet - Web to determine the age of an hvac system or water heater, begin your research by locating the brand name and serial number on the. 14th & 15th digits = factory code (01=oh; Web 7th thru 13th digits = unit identity #.
Web to determine the age of an hvac system or water heater, begin your research by locating the brand name and serial number on the. Web 7th thru 13th digits = unit identity #. 14th & 15th digits = factory code (01=oh;