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Hello and welcome to todays blog. I am Danny Hodgson a master chimney sweep.

Today you will learn the requirements for ventilation for: an open fire, a D.F.E and a stove/ room heater

Firstly why do i need an airvent?

  1. It is very important to let your solid fuel appliance breath properly this is done by using adequate ventilation from an outside source. A lack of ventilation can be dangerous it can also lead to poor burning, a reduction in efficency and Low heat production.
  2. Without adequate ventilation it is likely the fire will smoke back as it will gulp/ glug for air much like pouring a wine bottle.

Open fire

An open fire, must include an airvent of at least 50% of the throat opening, this is the narrowest part of the fireplace. This airvent is typically 5 inches in diameter. See below section 2 of approved j of builiding regulations for sizes of ventilation for solid fuel appliances.

A hodgsons chimney sweep devon will work to approved document j of building regulations

Stoves and roomheaters

If the house was built before 2008 then a vent is usually required only if the appliance is larger tha 5KW nominal output. The vent would need to be 550mm/2 per KW above 5KW. This means that a 7KW stove would require an airvent of 1100mm/2.

If the house was built after 2008 then a 550mm/2 airvent per KW is needed so for instance a 7KW stove will require an airvent of 3850mm/2.

It may be necessary to install an airvent in a property pre 2008 with a 5kw stove or lower if there is insufficent airflow. A Hodgsons chimney sweep can help you with your ventilation needs.

Chimney sweep devon can fit airvents


What is a d.f.e? A d.f.e is a decorative fuel effect appliance burning natural gas.

What are the requirements for ventilation for a D.F.E?

An open flued gas fire of more than 7kw input will require additional ventilation into the room of the appliance. Always follow the manufacturers guidelines and the guides of BS5440-2 when installing airvents for a d.f.e.

The minimum requirement for a d.f.e gas fire of 7KW or over is 10,000mm/2 or a square roughly 15.5inches/2

Any d.f.e gas fire which does not have a regulated input must have an airvent regardless.

The hodgsons chimney sweeps regularly sweep gas fires in devon Cast iron insert d.f.e

Wrong Ventilation

If you do not install the correct amount of ventilation your fire will become unreliable and possibly dangerous. When the fire is lit it uses oxygen from the room, this must be replaced by air from outside. If there is not enough ventilation the chimney will not function properly, this will cause the fire to be unsafe and unreliable.

Do airvents cause draughts?

Modern airvents do not cause draughts, like the vent pictured above, when installed correctly, they do not cause draughts.

In conclusion if you do not fully understand the requirements of ventilation, then you can ask one of us at Hodgsons Chimney Sweeps, follow the guides of section J of building regulations use a HETAS registered installer or HETAS approved chimney sweep.

If you would a greater understanding on how draught works then you can Learn more here

Thanks for reading.

Danny Hodgson Master Chimney Sweep Devon


  1.  Open fires versus stoves | Hodgsons Chimney Sweeps

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