Fireplace Ventilation

If you are considering reopening or installing an open fire some consideration must be given to room ventilation.  In older houses which have plenty of drafts through floors and windows no additional ventilation may be necessary, unless extensive refurbishments have been carried out then ventilation will be required.  Modern homes do require ventilation when an open fire is in use.

A range of commercial vents are available from DIY stores or reputable fireplace fitters.  They vary from simple grills to complex ducts that block drafts and sound while allowing ventilation.

The amount of ventilation you require (size of vent) according to UK building regulations must be equal to at least 50% of the area of the throat of the chimney or flue, and the vents must not be closable.

When reopening an old fireplace you shouldn't have to worry about this.  But if extensive works such as chimney relining has taken place, or a significant design change to the chimney which changes the size or fuel used, then the regulations must be complied with.

To comply with building regulations you have to show the vent can not be blocked, closed or removed by future common alterations such as, when new carpeting is fitted or new windows are installed.  Installers should position vents to minimise the chances of their becoming blocked either accidentally or deliberately by the home owner to stop noise or drafts.

Many a home owner has found their room to be colder after having a fireplace reopened or installed due to the position of their vent.  Another consideration is whether having an open fire is worth the noise, cold air and pollution that can come through the vent from outside.

The worst place to put a vent is at ground level far away from the fire because the cold air flowing into the room will not mix with the warmer air already inside the room.  Vents at ground level tend to create drafts around people's legs.

A better position would be to place the vent high up in the wall or ceilings far away from the fire.  This gives an even mixing of room and ventilation air, but it will also increase heat loss through the vent.

Best practice is to fit the vents on the wall around the fire.  The cold inflowing air then goes straight up the chimney without cooling the room air or causing drafts where occupants are sitting.  However, this position is rarely practical as most chimney breasts are within the middle of a house.

If you have any concerns about room ventilation, or the safety of your fireplace, please do not hesitate contacting me to arrange an assessment.