Does a room with a fire require a vent?
Yes. As mentioned in the previous question, a fire needs to draw oxygen to operate correctly. If there is no vent carbon monoxide may build up in the room. With a solid fuel appliance you will smell smoke in the room and with a gas appliance you will get a build up of carbon monoxide which you will not be able to smell but will eventually kill you. I always recommend fitting a carbon monoxide detector to alert you to any danger.
