If you have invested or are planning to invest in making your home airtight, the prospect of introducing a wood-burning stove can be a troublesome one. A heating source that is dependent on a flow of air in order to function is not in keeping with a sealed property.
Whether you are planning to burn logs or smokeless coal, the fuel will be reliant on a supply of oxygen in order to burn. The air must be drawn into the firebox and up the chimney in order for the stove to operate efficiently and to avoid smoke seeping into your home through the stove’s vents. Without a greater supply of air in your room, it is unlikely that your stove would operate correctly in an airtight room. Increasing the level of ventilation, which is usually achieved by putting air vents in the wall, would unseal your sealed home, create a draught and potentially increase your central heating bill.
The good news is that it is possible to install a woodburner without undermining the airtightness and energy efficiency of your room. The answer lies in external air stoves.
These are stoves that come with a spigot to allow you to connect the appliance to an air duct that will provide a direct air supply from outside. Since the air only travels through the duct and goes straight to the stove, you will experience none of the problems we mentioned above, such as draughtiness and a less energy efficient home.
The spigot, which is sometimes included with external air stoves and sometimes sold separately, will usually connect to a discreet location at the rear or underneath of the stove so as not to change the aesthetic of the stove. The opening is smaller than you might expect. Remember, the fire in a stove would only usually be dependent on the amount of oxygen coming through the air vents, so it needs far less than would be case for an open fire.
Types of direct air connection
There are a few different options available when installing an external air stove.
Partial This is when the direct air supply provides some of the air needed. Perhaps there is some ventilation in your room, but not enough for the stove to operate effectively. It may be the case that the primary air supply comes from the direct air duct, while the secondary air supply is drawn from the room.
Total This is when the direct air supply provides all of the air necessary for the stove to operate. The stove is not reliant on air from the room at all in order to function correctly.
Leak-sealed This is when, in addition to a total air connection, the appliance is sealed to prevent leakage. This would ordinarily done in cases where the property needs to meet set standards in order to achieve a particular certification. A prime example would be PassivHaus buildings.
Examples of external air stoves
There are plenty of external air stoves available to choose from. Here are a handful of the best for your consideration if you want the comfort and warmth of a wood-burning stove without impacting on the airtightness and energy efficiency of the rest of your home.
Thorma Wikantica 8 kW Wood Burning Stove
Not only does the Thorma Wikantica immediately make your room look better, it also includes a large storage drawer to help you keep your hearth tidy. It is a tall, free-standing stove in the continental European style and can be adapted to function as an external air stove. Have a closer look.
Thorma Falun 8 kW Wood Burning Stove
The Thorma Falun is very similar to the Wikantica, which is also made by the Slovakian brand. Again, it can be upgraded to an external air stove with the aid of a kit, which is sold separately.
Evergreen ST0311R Lymm 6.5 kW Multi Fuel Wood Burning Stove
One very reasonably priced option is the Evergreen Lymm. It has a 6.5kW heat output, which is appropriate for most medium to large living rooms and a very impressive return for an appliance that only costs £259 (price correct at time of writing). Have a closer look.
Thorma Andorra 7.5 kW Wood Burning Stove
The Thorma Andorra is a beautiful curved woodburner. Its stylish contemporary design and sleek lines are perfect for the modern decor of many airtight homes. As with the other Thorma appliances on this list, it can be amended to be used as an external air stove. Have a closer look.