How we designed and built the original storage heating stove at La Fattoria dell’Autosufficienza

“It’s warm even when it’s turned off”. This was one of the first comments received when the construction was completed. The original storage heating stove that you can see in these pictures is part of the renovation works carried out at La Fattoria dell’Autosufficienza by following green building principles.

The first thing that catches attention is the unusual double-flame shape that we wanted expressly as a symbol of La Fattoria dell’Autosufficienza.

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“The flame”, that is located in the wide common hall, is the attraction, reference and gathering point around which meetings, educational and entertaining activities are carried out.

While designing the stove we paid great attention in the difficult task of making this big structure, that is 3.4 meters high and weights over 3000 kg, as much light and soft as possible.

What is it and how it works

A storage heating stove, also known as Tiled Stove, Kachelofen, or more correctly, Kachelgrundofen, is a thermal mass stove built entirely with fine refractory material and according to the most advanced techniques of heating system construction.

It’s based on the ancient Roman principle of hypocaust and it’s equipped with a very thick and refractory central part where combustion takes place and from which a well-structured tunnel (8 meters long, in our case) twists and turns, gradually releasing heat to the refractory material.

Then everything is covered with a layer of refractory material at minimum distance of 2 cm. This layer gives the stove its final shape.

The heat is then accumulated and slowly released for the next 24 hours, with no need to add wood in the stove.

Advantages of a storage heating stove

This kid of heating system has many advantages and it’s particularly suitable for La Fattoria dell’Autosufficienza, as well as for other renovation works of stone buildings and for new constructions of energy efficient ecological buildings. Advantages include:

  • living comfort: thanks to its radiating heat emission, it gives the feeling of having “the sun within the building’s walls”, which in our case are made of stones, so they help creating further heat accumulation;
  • Health: heat radiation causes less air and dust turbulence and it doesn’t reduce inner air quality. This is particularly beneficial for those who suffer from asthma or other breathing problems. As well as sun rays, heat radiation deeply penetrate the body, providing a pleasant sensation and reducing stress during cold and dark winter days. It’s no coincidence that lately this heating system has been installed also in new hospitals and nursing homes in Austria and not only in spas;
  • Cost savings: for centuries wood has been the most economic energy source and, for this stove, wood consumption is very low, the lowest of all systems that use wood if compared to the volume of the space to be heated. In our case we only need one load of 14 to 29 kg, depending on the temperature outside;
  • Ecology: it’s an environmentally-friendly heating system. Indeed, wood is the only renewable heating source currently available;
  • Energy efficiency: it’s close to 90% efficiency for a complete thermal cycle. It doesn’t just heat as long as there is fire, as it happens for pallet or cast iron stoves, but also during the whole long cycle between one load and the other (usually between 12 and 24 hours);
  • Low-tech and autonomy: the total absence of electrical components guarantees the stove to always function, even if there is no electricity. For this reason, it’s particularly suitable for the self-sufficiency spirit of La Fattoria dell’Autosufficienza and for off-grid situations in general;
  • Low-maintenance: ashes need to be removed from the combustion chamber only a couple of times per season. The long tunnel and the chimney usually need to be cleaned every 15 years, time and costs of maintenance are almost non-existent;
  • Design: it’s an artistic stove that was built after careful design and calculations according to the current Italian laws and the strictest Austrian UNI regulations. The aspect of these stoves can be customized, so they can be adapted to any space and situation, unlike prefabricated stoves. The design is unique and it magnifies the beauty of the room, becoming a true attraction point;
  • Durability: if used correctly, the stove keeps on functioning for many years, generation after generation. In the Alps, there are heating storage stoves that date back to the XVIII century and that are still working;
  • Costs: the quality/price ratio makes these stoves very convenient if you think that beside all the advantages above mentioned, it can replace the classic heating system completely.

Storage heating stoves, if correctly designed, can have more levels in order to heat up a whole house with different rooms and levels.

The stove was designed and made by hand by Filo di Paglia
http://www.filodipaglia.it/portfolio/stube-di-giulia/