The future is here. Introducing the next generation of 82% efficiency, high performance, affordable, vented wall furnace heating solutions. The revolutionary design of the CARMEL™ TG2030TN allows natural gas to power all electrical components. It is self-powered - once the digital thermostat calls for heat, the electronic hot surface ignitor starts the furnace, then thermoelectric power takes over and converts the heat to electrical energy for continued operation.