Advisory - Speicherofen von der Tonwerk Lausen AG

Die Tonwerk Lausen AG

Die Tonwerk Lausen AG beschäftigte sich seit ihren Anfängen mit der Produktion feuerfester Steine sowie der Kunst, die Energie der Flammen so effizient wie möglich zu nutzen. Zusammen mit einem weltweit bekannten Designerteam und einem Spezialisten für Feuerungstechnik entstanden unsere einzigartigen Speicheröfen, die die Wärme im Kern eines von Tonwerk speziell entwickelten Steins speichern und als angenehme Strahlungswärme abgeben. Ein Feuerungssystem für eine umweltfreundliche und effiziente Holzverbrennung. Kompetenz in Technik und Design, verbunden mit der Handfertigung in unserer Manufaktur, unterstreichen die Individualität unserer Speicheröfen.



The condition and functionality of your chimneys must be inspected by a chimney sweep or specialist before the Tonwerk storage heating stove is installed. This will provide the optimal conditions for trouble-free heating.

Heating requirements

What do I want my Tonwerk storage heating to do?
Do I want to heat the room exclusively with a Tonwerk storage heating stove, do I want to augment the installed heating, or do I want to connect my Tonwerk storage heating stove to the central heating system? Your specialised dealer will assist you in all of these questions.

Specialised dealers

We at Tonwerk attach the greatest importance to consultation with specialised dealers.

Preparations for firing

Have ready an adequate supply of chopped firewood, ecofriendly lighting aids, and kindling. You are best storing the wood in a warm room for a number of days before firing.

Heating in the transition time and in difficult conditions

In damp or foggy weather, at outdoor temperatures from 15 °C, and during the transition time you are advised to light a pilot fire before firing the stove proper. This serves to displace the cold, heavy air in the chimney and to create the right conditions for the optimal extraction of smoke. This pilot fire is lit with paper in the chimney’s inspection aperture until extraction is assured.

Vent pipe and ventilating system

Extractor hoods and ventilating systems can affect the operation of your Tonwerk storage heating stove. Please make sure that there is adequate incoming air for multiple installations.

Drying paint on the stovepipe

When the stove is fired for the first few times the paint on the stovepipe emits an odour when it dries. Make sure that the combustion chamber is completely filled. The Tonwerk storage heating stove then reaches its optimal operating temperature and the paint dries faster. Also make sure the room is well ventilated during this phase.

Wood does not ignite when stove is fired | fire just smoulders away | fire extinguishes

  • open combustion air slide
  • kindling unsuitable
  • wood too damp
  • firewood too thick
  • ash drawer full

Heavy sooting in the firing chamber | heavy sooting on the window

  • open combustion air slide
  • too little wood
  • firewood damp or too thick

Smoke escapes from the stove

  • assure adequate extraction in the chimney, light pilot fire
  • provide for adequate supply of air

What is wood?

Do you know what you are putting in the firing chamber of your Tonwerk storage heating stove when you are filling it with wood?
This is 50% carbon, 42% oxygen, 6% hydrogen, and 2% mineral substances, nitrogen, oils, resins, tanning agents, and colorants

… that is wood!

Where can I get my firewood?

Regenerated ready-to-burn firewood can be purchased from dealers:
  • stove-ready, stored for at least two years
  • predried, stored for one year
  • fresh from the forest
Every dealer has a wood moisture meter, so test the wood you buy. The ideal residual moisture is 12–15% and should be no higher!

Unseasoned wood can be purchased from the forestry office, owners of woodland, or the community:
  • trunks lying in the forest
  • seasoned trunks by the wayside
Whether you have cut your own wood or bought it, the important thing is:
the wood should be dried for at least two years before it is burned!

Drying and storing wood

The water content of firewood has a great effect on its burning properties. Your wood should be as dry as possible. Only then can it give off much heat and burn without polluting the environment. Freshly cut wood can contain between 45 and 60% moisture depending on the season and type. After the optimal drying this water content drops to below 15%. Depending on the wood type this can take about two years, and even longer for some kinds.

Wood types and calorific values

The calorific value describes the heat energy released when one kilogram of fuel is burned under specific conditions. The calorific value is based on the volume specified in stacked or solid cubic metres.
The various wood types have various calorific values:

beech, oak, locust 2100 kWh/rm
birch 1900 kWh/rm
sycamore 1900 kWh/rm
Douglas fir, pine 1700 kWh/rm
larch 1700 kWh/rm
spruce, fir 1500 kWh/rm

A Tonwerk storage heating stove can be fired with all of the above wood types!

Units of measurement for wood

Solid cubic metre (scm):
As its name suggests, the solid cubic meter corresponds to one cubic metre of solid as opposed to stacked wood.
Stacked cubic metre (stcm) or stere (st): A stacked cubic metre or stere corresponds to one cubic metre of stacked wood including the gaps between layers. One stere equals 0.7 solid cubic metres.
Loose cubic metre (lcm): The loose cubic metre is a measure for chopped firewood that is loosely packaged for trade and transport. One loose cubic metre is 0.7 steres or about 0.5 solid cubic metres.

What happens when wood burns?

Burning or combustion is a rapid oxidation of substances forming flames. When wood burns, the oxygen in the air combines with the carbon and hydrogen in the wood. In the process, energy is released in the form of heat and light. In the ideal case the products of complete combustion are only carbon dioxide, ashes (formed primarily of the wood’s mineral constituents), and water.
The combustion process on firewood can be divided roughly into three phases.
Heating and drying – In this first phase the water and other volatile substances stored in the firewood evaporate.
Pyrolysis – In this second phase the firewood decomposes at temperatures from about 150 °C.
Actual combustion – In this third phase the gases formed in the first two phases react with additional oxygen from the atmosphere to form carbon dioxide and water. Also any remaining charcoal burns completely with time in the combustion zone. Only ashes remain as the single residue of combustion. Each phase of combustion can be observed very easily on an open fire.

Environmental protection

When firewood burns it releases only as much CO2 as the tree absorbed from the atmosphere while it was growing.
When the firewood was collected in the vicinity there are no additional CO2 emissions otherwise caused by the transport. Wood decomposing in the forest generates the same quantity of CO2 as the same wood burning.

General safety instructions

  • Never leave children alone or unattended at a burning fireplace.
  • Teach your children how to behave properly and operate safely the fireplace.
  • Every stove gets hot when fired: risk of burning!
  • Avoid touching the outside surfaces when the stove is operating.
  • Do not burn refuse or painted wood.
  • Dispose of the ashes only after they have cooled completely.
  • Inform your specialised dealer without delay of defect gaskets.
  • Observe the information in our operating instructions and make a proactive contribution to fire prevention and the protection of our environment.
Our specialised dealers are trained personnel and can offer you comprehensive advice on all questions on Tonwerk storage heating stoves.
Ask your local specialised dealer to contact you: he'll be pleased to offer you advice.