| A | B |
|---|
| Annual Fuel Utilization Efficiency (AFUE) | HVAC industry standard for defining furnace efficiency. |
| Atomize | The process by which a liquid is converted into a fine spray. |
| Combustion | The process by which a fuel is ignited in the presence of oxygen. |
| Condensing furnace | A furnace that contains a secondary heat exchanger that extracts latent heat by condensing exhaust (flue) gases. |
| Electrode | An electrical terminal that will conduct a current. |
| Flame rectification | The process by which a flame produces a sensible electrical current. The process by which a flame produces a sensible electrical current. A device, usually metal, that is used to transfer heat from a warm surface or substance to a cooler surface or substance. |
| Hot surface igniter | A ceramic device that glows when an electrical current flows through it. Used to ignite gas in a gas furnace. |
| Induced-draft furnace | A furnace in which a motor-driven fan draws air from the surrounding area or from outdoors to support combustion. |
| Infiltration | Air that enters a building through doors, windows, and cracks in the construction. |
| Manometer | An instrument that measures air or gas pressure by the displacement of a column of liquid. |
| Natural-draft furnace | A furnace in which the natural flow of air from around the furnace provides the air to support combustion. |
