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Combustion air vents

Combustion air vents provide a permanent supply of combustion air to rooms containing fuel-burning appliances which are not room-sealed. Maybe used to meet gas safety regulations and the requirements of Building Regulations Approved Document J1.


All open-flued fuel-burning appliances require an adequate supply of combustion air from the room so that:

  • The appliance and its flue operate efficiently.
  • Fuel is properly burnt, so harmful fumes are not produced.
  • The appliance will not draw oxygen from the air in the room.
  • Combustion products are properly vented through the flue to avoid any risk of build up inside the room.

The provision of an adequate air supply is a mandatory requirement of the Building Regulations J1. There is also a legal obligation when installing or servicing appliances to ensure that there is an adequate air supply.

This is particularly important when new windows or doors have been fitted, which are usually weather stripped, so cutting down the ‘Infiltration’ air supply.

To meet the requirement, a vent should be installed which must not be closeable, should prevent draughts, and must be large enough for the rating of the appliance.


Based on Approved Document J1/2/3, one pair of Combustion Air Vents is suitable for:

  • Gas appliances up to 18kW (61 000Btu/h) input.
  • Solid fuel closed appliances up to 14kW (47 000Btu/h) output.
  • Solid fuel open appliances up to 10,000 mm2 throat opening area.
  • Oil burning appliances up to 14kW (47 000Btu/h) output.

Bi-fold / Patio vent

Glazpart have led the market for special applications deleveloping a flat fly screen (grill) to allow background ventilationt o be supplied through operating bi-fold / patio door sets.

Sash Windows

Specifically designed for sash windows using the slimline trickle ventilator. Glazpart developed an offset clip to allow for lower plaster lines the ventilator is moved vertically relative to the 10mm slot for applications such as sash windows, where space is at a premium. These give offsets of +/- 2mm.


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Glazpart Ltd
Wildmere Industrial Estate
OX16 3JU

Tel: +44 (0)1295 264533