The Lennox 21G77 Transformer is an electrical component designed to convert 208/240V input power into the required voltage for compatible HVAC control circuits. Rated at 100VA, it supplies dependable power to thermostats, relays, contactors, and other control components in compatible Lennox furnaces, air conditioners, and heating systems. By providing the appropriate electrical supply... https://www.partshnc.com/21g77-lennox-transformer-208-240v-100va