When searching for a new gas-fired forced air furnace, there are three main choices. Each of these types of gas furnaces function differently and possess their own benefits. The most energy efficient systems are the modern condensing furnaces.

Conventional Warm Air Furnaces

Conventional warm air furnaces function by burning natural gas. This creates heat for the heat exchanger, which moves heat that the burning gas has created to the distribution system of the home. Air inside the house is heated by circulating around the heat exchanger. Through ducts, the air is then distributed throughout the house. Various other ducts transport cooled air to the furnace. There, the air is again heated and circulated again. More air is pulled into the flue, for ventilation. This air blends with the exhaust gases and then escapes via the chimney.

Conventional warm air furnaces are the least efficient type of gas furnace. Today’s minimum Annual Fuel Utilization Efficiency (AFUE) rating is at 78%. AFUE reveals how efficient a gas furnace is when transforming fuel into energy. The greater an AFUE rating is, the more efficient the gas furnace is. However, older conventional warm air furnaces have AFUE ratings as low as 55%! These furnaces contain a standing pilot, which functions as a gas burner’s tiny ignition flame.

Induced Draft Furnaces

Induced draft furnaces resemble conventional furnaces, though they contain a different system for venting. Conventional furnaces pull in air through a gap at the furnace front, and at the flue. This forms a natural draft. On the other hand, induced draft furnaces use a fan to pull in combustion products into the flue. This draft created unnaturally increases the efficiency of the furnace. Furthermore, unlike a conventional furnace, induced draft furnaces include electronic ignitions, rather than standing pilot. These ignitions can be either a hot surface ignition (HSI) or an intermittent pilot. The HSI is the most frequently used electronic ignition system in modern furnaces. This is because the HIS is dependable, generally cheaper, and needs electronic controls that have a lower price tag. These factors give induced draft furnaces roughly a 20% higher AFUE than a conventional warm air furnace.

Condensing Furnace

A condensing furnace is the most efficient type of gas furnace sold today. In fact, it is capable of having an AFUE as high as 97%! Condensing furnaces include an additional heat exchanger. The heat exchanger condenses water steam contained in the boiling flue gases. This helps to pull out extra heat for the house. The created flue gases have extreme low temperatures. Thus, a plastic pipe that can be installed through a side wall, can expel the flue gases horizontally, directly outside the house. The condensed water is then discarded through a drain located on the floor. The condensing furnace uses a hot surface ignition. In addition to being efficient, condensing furnaces also do not require a chimney, as exhaust escapes directly through walls in the basement. This allows you more options in the placement of the gas furnace, giving you the opportunity to easily reorganize your furnace room. If your house is already energy efficient, you can secure a unit that directly obtains combustion air from outside the house.

For all your gas furnace needs in Calgary - call Action Furnace today.

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