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Common Questions About Heating, Ventilation and Cooling
What is a direct vent furnace?
Direct vent furnaces are the compact high efficiency heating units. These furnaces have revolutionized the operation of the furnace. Unlike traditional furnaces which require a chimney or flue for venting, direct-vent units take advantage of zero-clearance technology. In direct vent furnaces, the air that is used for the combustion comes from outside the home. They do not require a masonry chimney or special flue and can be safely vented directly to the outside through a hole in an exterior wall.
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Although direct vent furnaces use gas as the fuel, they are a bit different from conventional gas-fired furnaces. A direct-vent furnace has a securely sealed combustion chamber which prevents leaks of combustion products into the room. Air used in enters the combustion chamber from outside through a small PVC pipe. The fumes which are produced due to combustion are exhausted through a similiar PVC pipe to the outside through a wall-mounted vent. As a result, air contaminated with combustion byproducts and unused fuel does not circulate in the home. Moreover, the household air is not used in the combustion process.
Direct vent furnaces are also known as condensating furnaces due to the fact that they use two heat exchangers which remove so much heat from the combustion fumes that the fumes actually condensate within the exhaust venting and have to be drained away through a condensate line. The addition of the second heat exchanges increases the efficiency from around 80% for normal vented furnaces to 93% and above for these high efficiency direct vent furnaces.
Direct vent furnaces will cost more initially than a standard furnace because of their construction (second heat exchanger, non-corrosive metal components, etc...) But they do cost significantly less to operate with a payback of about 3 to 5 years to recoup their additional cost.