A fireplace insert is essentially a stove, which can be fitted into a regular open fireplace. As with other wood stoves, a new fireplace insert has to be EPA certified, which makes them highly efficient and clean burning.
Electric fireplace heater inserts are generally made out of cast iron or plate steel with glass doors so that the flames can be seen. These inserts either jut out onto the hearth or fit snugly into the fireplace. The former position is considered to be more energy efficient since the bottom, top and sides radiate additional heat. They usually come with blowers, which can improve efficiency considerably. These blowers are generally either mounted on the sides or in front of the fireplace insert. While some blowers are manually controlled, others come with a thermostat to regulate the heat.
A Gas Fireplace Insert can be used to turn a regular wood burning fireplace, masonry as well as pre-fab, into a gas appliance that is sealed with glass on the front. Most of these gas inserts are equipped with fans to spread the heat, and also have wall-mounted thermostats or wall switches, and remote controls.
Gas inserts are far more efficient compared to vented gas logs, and the glass sealant in the front makes them much safer. A high quality gas infrared heater insert unit can produce BTU outputs which can range from 10,000-40,000 BTU, and has the ability to burn at up to 80 percent efficiency.
Most of them available these days are direct vent, meaning that they have a two-pipe venting system – one, which is designed to bring in the combustion air within the insert, and the second through which the exhaust is vented. It is a mandatory requirement to line the chimney right up to the top completely with two flexible stainless steel or aluminum pipes. This ensures that there is a correct balance between the intake and the exhaust, thus assuring safety while operating the unit.
Some of the models come with a B-Vent, meaning that they have a single pipe. These are a little less efficient compared to the direct vent type since they use the air inside the house for combustion. The B vented gas convector heater fireplaces also must be lined right up to the top of the chimney, except that only a single pipe is used in this.