Gas Venting Types

  August 20, 2019      Bradford White


Non-Mechanical Vents

Non-mechanical vents use the density difference between hot exhaust and cooler ambient air and have 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 of the wall, not through the ceiling.
  • Does not require any power (standing pilot).

Mechanical Vents

Mechanical vents use a powered blower to expel exhaust gases through the vent system and have 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).