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  • As the furnace sends warm air throughout a home via the duct system, non-heated air is captured in the cold air returns. This air is circulated back into the furnace where it is filtered, reheated and returned back to the living areas of the residence.
  • A vent connector is the primary pipe that leads from the furnace to a chimney or another vent.
  • A draft inducer is a fan system that is located next to a furnace’s heat exchanger. Before the system ignites its burners to warm the heat exchanger, the draft inducer is turned on to push out any combustion gasses into the flue pipe that might still be present from the furnace’s last heating cycle.
  • A drip leg is an important part of a furnace’s gas line, as it traps sediment or debris that has traveled through the gas line. The drip leg prevents these impurities from entering the furnace.
  • The gas valve controls the flow of natural gas into a furnace. Operated by electromagnets, the safety valve allows just enough gas into the furnace to ignite the pilot light. The main valve provides gas to the system’s burner assembly.
  • The air filter not only purifies the air that people and pets in the home breathe, but it also prevents dander, dust and debris from entering the furnace itself which can cause damage.
  • The circulating fan is the main blower system in the furnace that moves warm air through the entire house.
  • The pilot light is a small flame source that stays on at all times within a furnace, regardless if it is running or not. When a heat cycle begins, the pilot light ignites the gas that is released into the burner assembly.
  • A burner is the part of a furnace that mixes natural gas and air, which is then ignited by the pilot light to produce a flame to warm the heat exchanger.
  • A furnace heat shield or sometimes known as a flame rollout shield is a barrier that protects furnace components from excessive heat or damage when flames extend past their proper position in the burner assembly.
  • The fan limit switch controls how often the furnace’s blower assembly turns on to push warm air around a home. This unit is also responsible for turning the blower assembly off at the proper time. In addition, the fan limit switch monitors whether a furnace should be shut down in the event of an overheating malfunction.
  • The heat exchanger is both a metal chamber and passageway that is heated by the burner assembly. As air passes over the heat exchanger, it is warmed and blown around the house through the duct system. It is critically important that the heat exchanger does not leak any flue gasses trapped within it, as highly dangerous fumes such as carbon monoxide can be fatal to both occupants and pets.
  • This is air that has been taken into the furnace, heated and then evenly distributed throughout a home via the duct system.