Premier Gas specialise in the installation of gas log fires and space heaters in both open flued and direct vent configurations. These appliances can be inbuilt, usually into a false fireplace (constructed of framing and gyprock) or a brick chimney opening, or freestanding where the flue is seen in the room
Open flued (also known as conventional flue) is when an appliance draws its combustion air from within the room it is installed. Open flue appliances are less efficient. An open flue appliance must sacrifice some efficiency in order to vent unwanted products of combustion from the house. By allowing flue gases to retain high temperature, the natural force of rising hot air creates chimney draft, which contain water vapour, carbon dioxide and oxides of nitrogen: all products of combustion. At the same time, air from the room is drawn into the burner to maintain combustion. In most cases it will be the heated air. If there is insufficient air for the combustion process, poisonous carbon monoxide will be produced at the burner. When there is down draft in the chimney this poisonous gas will be carried into the room.
Direct vent is when an appliance draws its combustion air from outside.Also known as balanced flue, this consists of two ducts, one inside the other. The fresh air for the combustion is taken from the outer duct and the products of combustion is taken out by the central duct to out side the house. Hence the balanced flue terminal may only be fitted on an external wall, although some appliances can be vertical flued. The combustion is independent of any air supply within the room, these appliances are often called room sealed. Balanced flue are more efficient than open flue appliances.
Some appliances now are fan assisted. The flue fan provides the fresh air to the burner and also removes the products of combustion from the combustion chamber. The combustion is independent of any air supply within the room. Hence these are room sealed. There is no need for the flue gases to have thermal energy to drive the gases out, these appliances are more efficient than the balanced flue.