One question that regularly comes up here at NCC flue supplies is whether a wood burning stove needs an air vent.
To operate correctly all stoves require a supply of air for combustion, and the ability to then evacuate the flue gases; otherwise they will not work. A wood burner is unable to light without an air supply, and subsequently smoke will then pour out into the room it is installed, not what you want to happen. To allow the smoke to be able to be drawn up the chimney continuous air movement is required up through the chimney, this cannot be achieved if there is no source of air. A good test is to check if the burning of your stove improves when opening a window or door in the room if so, it is more than likely you need to install some correct air ventilation. Also, the addition of a high-quality chimney cowl can also improve the airflow and prevent nasty downdraughts.
As a rule, all airtight properties, especially new builds, require an air vent that can not be closed or be covered up, i.e. permanently open and venting to the outside of the property. The vent should also be located in a place where the householder cannot cover it up.
Depending on what size KW your intended stove is rated at will determine the size of the air vent aperture which increases on the KW rating. Roughly speaking the air vent needs to be around the size of a 50p piece per KW, so, for example, a stove with KW rating of 5kw needs an air vent aperture of 5 x 50p pieces (the exact figure is 550 mm of vent per KW)
If a property is deemed not particularly airtight, such as an older property the air permeability must first be measured. Although any house built before 2008 will unlikely require the strict air vent rule unless it had been made airtight. If the property has been developed since 2008, then it's best to carry out this test.
An underperforming stove can also point to reduced airflow and the lack of an air vent. A good check to carry out is to open a window in the room that the stove is situated while the stove is lit and if the performance improves this points to an issue and more air is required in the room.
There are many solutions to counter the cosmetic impact of having to install a vent. Some stoves on the market have integral air vents, a pipe travels directly to the outside with no hole to leak heat. If the floor in the room is a suspended floor with a cavity underneath it is more than likely this area is vented, and a vent can be installed in the floor, even where a carpet is fitted.
Where a property is built with thick stone walls and drilling is not possible then alternative solutions are to either remove a glass panel from a window and fit a vent or use an existing cat flap in a door.
In review, correct air venting will impact on the quality of the performance of your stove, knowing the best way to light your stove also has an impact on the efficiency of your wood burner. It's best to spend some time getting to know your wood stove and experiment with what works best as each stove is slightly different, this can apply to the same model stove operating differently in separate houses. Primarily this is due to the flue or chimney; however, other elements within a room can affect how air flows through a vent and affect the performance of a stove. We recommended a qualified professional takes on the task of installing a wood burner and fitting the best air vent solution for your property.