The firebox is the nerve centre of the fireplace and it affects the entire operation of the fireplace. The fireplaces function on the counterflow principle, which recovers the thermal energy from the hot flue gases. The hot flue gases rise from the firebox to the upper combustion area and to the side channels, where the thermal energy transfers to the body of the fireplace. From the body, the heat radiates evenly to the surroundings. This also creates a rising air flow outside the fireplace that warms up, which transfers heat slowly and softly to the room.
A fireplace with a bakeoven is a heat-retaining combination fireplace where the fire in the fireplace heats the bakeoven above it. Wood is burned only in the firebox, and from here the flames and non-combustible gases rise to the bakeoven, which serves as the upper combustion area. In the bakeoven chamber, the temperature during combustion is over 800 °C.
This temperature ensures that the fire in the bakeoven burns cleanly and heats up the bakeoven to a suitable baking temperature. The firebox is also equipped slots to hold a grid, so that it can be used for heating and baking as well. A cooking grid is included in the delivery. The same instructions apply to combustion air intake as for fireplaces.
Fireplaces with a bakeoven have a unique structural solution that enables the bakeoven door to be placed on any side of the fireplace. The other sides can be used for the flue connection.
Top-vented fireplaces can be equipped with a by-pass damper, which takes the combustion gases directly to the flue. A by-pass damper can be used to ensure that a fireplace at a holiday home has sufficient draught. In top-vented solutions, the highest allowed flue weight is 750 kg.
When the firing of a fireplace is started, combustion air can be taken either from outside from under the fireplace (independent of indoor air) through the flue or from the room through the maintenance door. The fireplace has an easy-to-use control for air intake. The control has three settings: off, combustion and embers. The air intake must remain in the combustion position until the firebox contains only embers, which can then be burned rapidly by moving the control to the embers position.
In older buildings combustion air often has to be taken from indoors. This also applies to newer buildings when a fireplace is installed at a stage of construction when it is too late to consider other combustion air options.
When taking combustion air from indoors, you may encounter the problem that the fireplace has insufficient draught because there is not enough combustion air. In such cases, the easiest solution to get enough combustion air is to open a window or door.
If combustion air is ducted directly from outdoors, it is important that the air flows freely. When using the fireplace, it is important to close the air control lever immediately after firing, as shown in the user manual, to prevent cold air from flowing through the fireplace, thus cooling it.
If combustion air is taken directly through the flue, it is important to close the air control lever immediately after firing, as shown in the user manual, to avoid the air in the flue flowing in the wrong direction due to lift. When adding firewood, contrary to the instructions for normal use, it is also a good idea to close the air control lever of the fireplace to prevent lift in the fire ventilation duct.