The following description applies for the modul G and L models. Models U1 and U2 have a lower accumulator effect because of their very large glass surfaces.

It seems impossible to satisfy all these wishes in one stove system, after all some of the demands are mutually exclusive. But the modul delivers all the requirements listed above in a single stove system thanks to its unique technological design and combination of different materials.

The room air that warms up in the intermediate space escapes unnoticed through a shadow gap on the top of the modul and is discharged into the room as "gentle convection".1

The natural stone casing2; as a whole heats up and delivers comfortable, long-lasting radiated heat into the living space. The long-wave radiation has the effect of warming adjacent walls and objects as well, and these give off radiated warmth in their turn.

The modul cover also delivers comfortable, long-lasting radiated heat to the room. 

Fast radiated heat after ignition through the glass ceramic window.


Room air warms up and rises in the intermediate space.


The room air is directed efficiently between the heating installation and the natural stone casing in the plinth area of the modul.

The right mixture: The three stages of heat emission

  • Immediate, fast heat radiation through the glass ceramic window
  • Fast, long-lasting "gentle convection"1
  • Warming of the entire stone casing2

The monolith modul delivers warmth to the room in three different ways. As a rule of thumb, the heat that is generated first also ends first. The radiated heat through the viewing window begins quickly after burning starts. Shortly afterwards, the "gentle convection"1 begins. Finally, the radiated heat from the stove casing takes effect as the last heat source. This often takes place at the same time as the fuel source burns down. The radiated heat provides many hours of comfortable, pleasant radiated warmth.


Heat output stage 1

Fast radiated heat after ignition through the glass ceramic window. The whole fire chamber is made from high-quality refractory clay bricks which guarantee a long service life and heat storage efficiency. 

Heat output stage 2

Fast, long-lasting "gentle convection"1, generated in the space between the heater equipment and the stone facing The "gentle convection"1 begins shortly after the stove system is ignited.

Heat output stage 3

Warming of the whole stone casing2 takes a little longer. This soothing radiated warmth lasts for a long time because of the high storage mass of the natural stone.

Soothing radiated warmth is created by the warm surface of the rock. The aim is to maintain this comfortable heat radiation for as long as possible. The great density and consequently great mass of the natural stone makes a very good heat accumulator. In this respect, materials with high mass typically have more storage potential than materials with low mass.4 For example, natural stone has about 50% more mass than refractory clay.5 It also has greater mass than kiln ceramic. The natural stone absorbs the radiated heat from the heater equipment during the combustion process and then releases it into the room more slowly as long-wave, comfortable radiated warmth over a long period. For example, the rock_G1XL stove model

weighs almost 500 kg.6


In general, two different kinds of heat release can be distinguished: Radiated heat and convection heat. As a rule, the heat from steel fireplaces is released in the form of convection heat, i.e. hot air is given off into the room. This hot air then rises to the ceiling, sinks at it cools and is drawn into the stove again. The advantages of this kind of heat are that it is given off quickly, and it also warms areas which are not in the immediate vicinity of the stove. Its disadvantages are the short storage effect and dry air, since the circulating air stirs up dust particles. The warmth of the air in the room is also uneven – it is warmer towards the ceiling, colder close to the floor.


floor burner8

Floor burner stoves release heat mainly in the form of comfortable radiated warmth, i.e. the warm surface of the stove system imparts long-wave radiated heat to the room, and the delimiting walls, and these also heat up and themselves produce radiated heat. The heated walls reinforce the insulation effect. The air temperature in the room is even, and air movement is low - consequently very little dust is disturbed. The disadvantages of this form of heat emission are that it is slow and not very flexible. For example, the floor burner stove usually only begins to radiate heat after 1-2 hours. It is also difficult to heat areas of the room which are not in the immediate radiation range.


The rock combines the advantages of these two stove types with ideal results. With direct radiation through the viewing window and gentle conversion, fast, flexible heat is released. At the same time, the wholenatural stone casing is charged with thermal energy. The stored heat is then released over a long period in the form of comfortable, long-wave radiated heat, ensuring a pleasant room atmosphere.

1Convection is described as gentle because the velocity of the air is slower over the convection period as a whole than with pure steel stoves, which do not include accumulators. 2The natural stone casing may stay cold in certain areas of the plinth. 3The diagram serves only to illustrate heat emission, it does not represent an actual correlation of time to temperature. 4Storage is also dependent on other influences and material properties. 5Comparison of Nero Assoluto natural stone with extruded refractory clay quality. 6Weight with accumulator 7 The weight dimension does not reflect the ratio of individual dimensions to each other. Materials used: Lightweight concrete, extruded potter's clay, kiln ceramic, Nero Assoluto natural stone.  8Rough diagrammatic representations - only intended to support the explanations in the text. 9The natural stone casing may remain cold in certain areas of the plinth.

Contact us:

CB-tec GmbH

Behaimweg 2

DE-87781 Ungerhausen

Tel.: +49 (0) 8393 - 9469 - 0

Fax.: +49 (0) 8393 - 9469 - 999

alexandra_mayer62 in Woringen, DE auf Houzz
CB stone-tec GmbH bei homify

Exclusive sale of monolith fireplaces in foreign markets. Spartherm does not have the right to sell goods in the following countries: Germany, Austria, Switzerland, Luxemburg, Lichtenstein, Malta.