Walltherm® AIR - radiant heat stove
Gasification woodstove with natural draft and hot air distribution
Power: 6 - 12 kW
Efficiency: >87 %
Emissions: 12,4 mg/N³
Combustion air connection from bottom: ø180 mm
Combustion air connection from behind: 2 x ø100 mm
Chimney draft: 13 Pa - max. 20 Pa
Weight:~ 300 kg
Chimney connection: ø150 mm
Exhaust stream: 10,1 g/s
Exhaus gas temperature: ~179 °C
Exhaus gas temperature (lighting phase): ~ 250 - 300 °C
Fuel: dry wood (under 20% humidity)
Length: up to 35cm
Warranty: 5 years on the body (wear parts excluded), 2 years on fittings and electrical components
Frequently asked questions
The Walltherm works with the natural draft of the chimney, the draft is therefore very important. It must not be less than 12Pa and 15Pa would be great. Your sweep can measure the draft and confirm the values.
A chimney of 6m or more of vertical lenght and a (round) diamenter of 150-200mm is usually perfectly working. The chimney must be insulated! Horizontal smoke pipes reduce the draft so avoid them if possible. Connecting the stove with a 45° or 60° angle to the chimney is better than 90°.
No. While heating up the Walltherm, the fume flap is opened and the fume can exit the stove with relatively high temperatures of more than 300°C. This will preheat the chimney and the humidity dries out. Only after the chimney is hot, the gasification process is started. The exhaust temperature drops to 130-170°C but because of the clean burning, chimney sooting will not occur.
Wood should be stored in a dry place for at least 2 years before burning it. The humidity should be be less than 20%, however, 15% is even better. Both soft and hard wood can be burned.
The combustion chamber is designed for wood logs up to 35cm lenght, and it has a capacity of ~50 liters.
The consumption depends mostly from the type and quality of the burned wood, but generally you can expect around 3-4 hourst of burning with soft wood and around 5 hours with a full load of hard wood.
If the chimney draft is strong enough, there shouldn´t be much smoke coming out of the stove. Before opening the doors you would open the exhaust fume flap, so most of the smoke can exit through the chimney. The best solution is not to open the doors before all the wood is burned down.
Removing the ashes from the upper and lower combustion chamber is done daily before lighting the stove. Once in a week you should remove the cast iron grids from the upper combustion chamber and clean the ashes out of the ash boxes below. This is done easily with an ash vacuum cleaner.
The heat exchanger is cleaned with long steel brushes which are delivered together with the stove. To clean the heat exchanger you must remove a cover behind the chimney tube exit on top of the stove. The fume channels lying below are then cleaned with the steel brushes while all the dirt falls down into the lower combustion chamber from where it can be removed with an ash shovel. This procedure is done every 6-8 month.
Every 2-3 years you will need to change the sealings of doors and cleaning openings. The injectorblock made of stainless steel and the cast iron grids will last for approximately 2-5 years, depending on how much the stove is murning. Refractory stones can get cracked on the surface which doesn´t neccessarily mean that they need to be replaced. Only after 5-8 years they will start crumbling, then you should replace them. In individual cases the glass of the lower combustion door can get opaque because of the extremely high temperature exposure, this will require a replacement glass.