Today's hearth products are vented in three ways: natural draft or "B" vent, direct vent or vent-free. In most cases, solid fuel hearth appliances are vented by natural draft. Below are the options for gas hearth appliances.
Natural Draft (Class B) Venting
Natural draft hearth appliance take in combustion air from the home and vent products of combustion outside the home.
Direct vent appliances draw combustion air from the outdoors and exhaust its combustion products to the outdoors, eliminating the need for a standard chimney system. A glass panel in direct vent units is critical to keeping the combustion system sealed from the home, maintaining high efficiency and indoor air quality. Direct vent piping can go out the wall directly in back of the unit or go upward from the top of the appliance then though the wall.
Unvented or Vent-Free
Unvented and vent-free refers to the kind of hearth appliance that draws its combustion air from inside the home and is designed to burn so efficiently that it eliminates the need for venting.
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