Although traditional woodburning fireplaces and coal burning fireplaces have a very obvious aesthetic appeal, it is true that they may actually exhaust more heat from a house than they produce. As a result manufacturers have developed various fireplace doors and other accessories to reduce this heat loss. A typical vertical-back fireplace with an open front is at best 10% efficient in converting solid fuel to heat a room and the rest of your wood dollars will escape up the chimney. They can also pull cold air into the house through small gaps around windows and doors. At the beginning and end of an open fireplace's use these heat losses can be larger than the radiant heat provided by the fire. Additionally most fireplaces are placed onto exterior walls and the surrounding masonry is a poor thermal insulator and readily conducts room heat to the outside.
Fireplace doors are a cheap and easy way to reduce heat loss from a fireplace and are an easy do-it-yourself project. By reducing airflow heat loss up the chimney is restricted. Glass fireplace doors have four major components: a frame with adjustable air intake slots or vents, tempered glass doors, an interior screen and special brackets or anchor bolts for securing the frame to the fireplace. Some kits come with both fireplace mantels and doors, whilst others combine fireplace screens and doors.
How much energy a glass fireplace door saves depends on how it is used. Burning with the glass fireplace doors open is the same as not having doors at all. Closing the fireplace doors during the burn allows for better control of the fire, but reduces the amount of radiant heat transferred into the room from the fire. But even so the loss of some radiation is preferred over the uncontrolled air movement up the chimney. Always ensure that the fireplace doors are shut just after the most intense part of the burn, when the fire is dying and when the fireplace is not in use. Be certain also to close the air vents as well as the chimney damper.
Most bifold glass fireplace doors are made of tempered soda-lime glass, which being a tough safety glass adds mechanical strength, but this can be compromised if the fireplace glass doors are not kept clean. If the fireplace doors are blackened by soot and creosote then reduced radiant heat transfer will result and may even weaken the glass during the extreme temperature changes within the fire.
When looking to acquire and to install fireplace doors, look for models with a rigid frame and a fibreglass seal that fits against the outside rim of the fireplace opening. The frame should fit securely, the doors should seal tightly, and the inlet vents should be adjustable. It is important if you have a factory built fireplace to check whether the unit is approved for use with glass fireplace doors. Custom made glass fireplace doors are obviously more costly than mass produced kits but allow far greater expression in design. Manufacturers such as Majestic fireplace doors and Heatilator fireplace glass doors produce doors to the common size of 26 inches by 26 inches and Superior fireplace doors produce iron fireplace doors. For the best reviews of fireplace doors the World Wide Web is the best resource.
