The Furnace Accessories are unique and feature a contactor, sequencer, and transformer. Gas furnaces have key parts such as gas valves and draft inducer motors that electric furnaces dont have. The furnace is a part of the heating, ventilation, and air conditioning (HVAC) system. People activate the furnace when they set the temperature in a room by using a thermostat. The furnaces have key parts such as gas valves and draft inducer motors that electric furnaces dont have. Furnace Accessories are very effective.