How does a furnance work?

Answer 1

1. The Burner
2. The heart of a gas furnace is the burner. Most gas furnaces have two or more burners controlled by a thermostat. When the temperature in the house falls below a certain level, gas begins to flow and an electronic ignition system ignites it. This hot, combusted gas rises past a heat exchanger and out through a vent that leads to the outside of the house. Air Circulation
3. A motor in the gas furnace pulls in air from an exchange -- a large flat grill in the floor, ceiling, or wall of a house. That air flows through ducts into the plenum of the furnace. The plenum is on the opposite side of the heat exchanger from the burner. Heat from the combusted natural gas warms the air as it passes by. The warm air is then taken back into the house through ducts that run to vents. Many houses have vents in every room. Maintenance
4. Modern gas furnaces are very efficient when their first installed, but that efficiency can rapidly decline. New furnaces often come with flimsy air filters which break down quickly. If the filters are not replaced, dirt gets into the air ducts. Ducts can also pull apart at their joints, leaving leaks. This decreases the efficiency of the whole system, because hot air can leak out under the house. Fortunately, most duct leaks can be fixed with simple HVAC tape. One of the most common problems in older furnaces is dirty burners. As grime accumulates over time, the burner becomes less efficient. It produces less heat and doesn't completely burn the gas, resulting in a colder house and higher heating bills. Fortunately, many burners can be cleaned with nothing but a wire brush.

Answer 2

A furnace works by burning fuel to generate heat, which is then circulated throughout a building to provide warmth. The fuel combustion heats up a heat exchanger, and air blown over the exchanger is warmed and distributed through ducts to various rooms. The combustion gases are vented safely outside the building.