Fires require oxygen to burn and current regulations state that stoves over 5 kilowatt output require an air vent of 1 square inch (645.16 sq mm) per kw. Stoves under 5kw do not require an air vent, unless the property has been built since 2010, the room has more than one chimney or there is an extractor fan nearby. In these circumstances, please contact us for further advice.