Gas Venting Types

   May 31, 2016      Bradford White



  • Uses the density difference between hot exhaust & cooler ambient air
  • Negative vent pressure

Atmospheric Vent

  • Most common venting style, also known as “Chimney Vent”
  • Uses surrounding air for combustion and exhausts through the flue
  • Vents with B-vent or lined chimney
  • Must use a draft diverter

Direct Vent

  • Uses outside air for combustion and exhausts to the outside (concentric vent) (pipe within a pipe)
  • Vent goes out the wall not through the ceiling
  • Does not require any power (standing pilot)


  • Uses a powered blower to expel exhaust gases through the vent system
  • Positive vent pressure

Power Vent

  • Uses inside air for combustion and vents either horizontally or vertically using PVC, CPVC, or ABS material
  • Uses 1 pipe for venting the exhaust
  • Requires power to vent exhaust (blower motor assembly)

Power Direct Vent

  • Uses a twin pipe system, pulling air from the outside for combustion and venting exhaust to the outside with a separate pipe (sometimes concentric)
  • Typically installed in applications where there is a lack of combustible air
  • Requires power for intake and exhaust (blower motor assembly)