page_title: Furnace
section_title: Condensing
hierarchical_section_title: Furnace / Categories / Condensing
caption_attribution_description: English: Condensing furnace diagram
context_page_description: A furnace, referred to as a heater or boiler in British English, is a heating unit used to heat up an entire building. Furnaces are mostly used as a major component of a central heating system. The name derives from Latin word fornax, which means oven. Furnaces are permanently installed to provide heat to an interior space through intermediary fluid movement, which may be air, steam, or hot water. Heating appliances that use steam or hot water as the fluid are normally referred to as a residential steam boiler or residential hot water boiler. The most common fuel source for modern furnaces in North America and much of Europe is natural gas; other common fuel sources include LPG, fuel oil and in rare cases coal or wood. In some areas electrical resistance heating is used, especially where the cost of electricity is low or the primary purpose is for air conditioning. Modern high-efficiency furnaces can be up to 98% efficient and operate without a chimney, with a typical gas furnace being about 80% efficient. Waste gas and heat are mechanically ventilated through PVC pipes that can be vented through the side or roof of the house. Fuel efficiency in a gas furnace is measured in AFUE.
context_section_description: The fourth category of furnace is the high-efficiency, or condensing furnace.  High-efficiency furnaces can achieve from 89% to 98% fuel efficiency. This style of furnace includes a sealed combustion area, combustion draft inducer and a secondary heat exchanger.  Because the heat exchanger removes most of the heat from the exhaust gas, it actually condenses water vapor and other chemicals (which form a mild acid) as it operates.  The vent pipes are normally installed with PVC pipe versus metal vent pipe to prevent corrosion. The draft inducer allows for the exhaust piping to be routed vertically or horizontally as it exits the structure.  The most efficient arrangement for high-efficiency furnaces includes PVC piping that brings fresh combustion air from the outside of the home directly to the furnace.  Normally the combustion air (fresh air) PVC is routed alongside the exhaust PVC during installation and the pipes exit through a sidewall of the home in the same location. High efficiency furnaces typically deliver a 25% to 35% fuel savings over a 60% AFUE furnace.
caption: A condensing furnace
exif: {}