Regulations: Gas Appliance Ventilation in England & Wales

A good air supply is essential to the safe working of a heat producing appliance.  The amount of air required will depend on the type of appliance, the input/output and the type of fuel it burns.  For your convenience, we have created a ventilation calculator for two popular gas appliance installations (see below) and outlined extracts from the following regulations:
  • The Building Regulations, Approved Document J (2010 edition incorporating 2010, 2013 and 2022 amendments in England) and (2010 edition incorporating further 2010 amendments in Wales).
  • For detailed guidance, refer to the full versions of the regulations linked above.
Approved Document J: Combustion appliances and fuel storage systems
Requirement: Air supply

J1: Combustion appliances shall be so installed that there is an adequate supply of air to them for combustion, to prevent overheating and for the efficient working of any flue.

Section 1: Provisions which apply generally to combustion installations

1.10: Permanently open air vents should be non-adjustable, sized to admit sufficient air for the purpose intended and positioned where they are unlikely to become blocked.  Ventilators should be installed so that building occupants are not provoked into sealing them against draughts or noise.  Air vents should not be located within a fireplace recess except on the basis of specialist advice.

1.16: In noisy areas it may be necessary to install noise-attenuated ventilators to limit the entry of noise into the building.

Section 3: Additional provisions for gas burning appliances with a rated input up to 70kW (net)
Flued Decorative Fuel Effect (DFE) fires

3.11: Any room or space intended to contain a DFE fire should have permanently open air vents as described in (a) or (b) below, unless the installation is in accordance with Paragraph 3.12:

a. for a DFE fire in a fireplace recess with a throat, the air vent equivalent area should be at least 10,000mm² (100cm²)
b. for a DFE fire in a fireplace with no throat, such as a fire under a canopy, the air vent should be sized in accordance with Section 2 of this Approved Document, as if the room were intended to contain a solid fuel fire (see Table 1).

3.12: In dwellings with an air permeability greater than 5.0 m³ /hr/m² (see Appendix F), permanently open air vents may not be necessary for DFE fires with ratings not exceeding 7kW (net) that have a flue gas clearance rate (without spilling) not exceeding 70 m³ /hour.

Flued appliances other than decorative fuel effect fires

3.13: These appliances include inset live fuel effect (ILFE) fires, radiant convector fires and boilers, in both room-sealed and open-flued variants.
3.14: A way of meeting the requirement would be to follow the guidance in Diagram 32.

Air supply to flueless appliances

3.15: For some flueless appliances, it may be necessary to provide permanently open air vents and/or make provision for rapid ventilation as recommended in BS 5440-2:2009 or equivalent, to comply with Part F as well as Part J of the Building Regulations.  Some ways of meeting the requirement when installing flueless cookers (including ovens, grills or hotplates), flueless water heaters and flueless space heaters are given in Diagram 33.

3.16: A room containing a gas point intended for use with a flueless appliance (such as a gas point for a cooker or a gas point for a space or water heater, the gas point not being adjacent to a flue) should have the ventilation provision required for the installation of that appliance (calculated on the basis that an appliance with the largest rating consistent with the table to Diagram 33 could be installed there).

Make a gas appliance calculation
House Year
Air Permeability:
Appliance Type:   
Appliance kW Input (net):   

General notes:

  • This calculation assumes the air vent will be in the same room as the appliance and positioned to access directly to the outside.
  • Rytons AirCore and AirLiner ventilation sets feature anti-draught systems to promote a comfortable environment in the room.  Achieve further draught protection by placing the air vent close to the appliance or at a high level close to the ceiling.
  • Rytons through-wall stove ventilators have equivalent area calculations as required by Approved Document J.
Rytons Gas Appliance Ventilation Range
Achieve compliant gas appliance ventilation with Rytons comprehensive range of ventilators.  We are always happy to assist you with ventilation calculations and product selection; call our technical sales office on 01536 511874 for advice.
Rytons Acoustic AirCore® and AirLiner® Ventilation Sets
Rytons Unsilenced AirCore® and AirLiner® Ventilation Sets
Rytons Floor

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