The greatest strength of the depot is its storage effect

The following components of the monolith depot work together for this:

  • The accumulator core, made of heavily compressed accumulator refractory clay
  • The solid, natural stone stove casing


Both components are characterised by their high mass and good storage effect. This ensures that the depot can continue to release comfortable radiated heat into the room even many hours after the combustion process has ended. The accumulator core also clad entirely with a steel shell. This ensures good insulation. A ventilated intermediate gap is located between the insulated accumulator core and the natural stone casing. The air from the room is actively drawn into this space and released through a shadow gap at the top back into the room as "gentle convection"1. This provides a faster, more flexible way to release heat and also helps to protect the natural stone casing from overheating. However, most of the heat is transferred to the natural stone casing by direct radiation from the accumulator core, and from there it is also released into the room as long-wave radiation.

Die Stufen der Wärmeabgabe im Überblick

Heat output stage 1

Fast radiated heat after ignition through the glass ceramic window. 


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.

monolith depot - the storage expert

1. The accumulator core

The heart of the monolith depot is the accumulator core. This is where the first phase of heat storage takes place. The entire accumulator core consists of heavily compressed accumulator refractory clay system elements. The formulation of the refractory clay is adapted specifically to the requirements of the monolith depot. The manufacturing process involves compressing this special refractory clay material into the shaped parts under extremely high pressure and then firing it.


The accumulator core functions according to the "floor burner principle" – i.e. it consists of a fire chamber and the following ducts, the smoke extractors – all made from refractory clay. The high temperatures and gases which are then formed during burning are diverted through the smoke extractors on the way to the flue and are stored there. Refractory clay is ideally suitable for storing heat. The smoke gases cool down on their way to the flue – as much energy as possible is kept in the stove – only the bare essential heat is allowed to reach the flue.

For example, in tests the monolith depot_G1 achieved an efficiency level of more than 90%.3

2. The storage casing

The second storage medium after the accumulator core is the natural stone casing.

Natural stones are formed over millions of years under enormous pressure. The consequence of this is that natural stone is typically extremely dense and very heavy. Accordingly, natural stone is a very good heat storage medium. Very heavy materials usually have greater storage potential than materials with less mass. For example, natural stone has greater mass than kiln ceramic. The two constituents natural stone and refractory clay thus make an excellent combination and are ideal for delivering long-lasting, comfortable radiated heat for many hours.


The monolith depot_L2 | L3 stove models weigh over 800 kg, for example.

The components of the monolith depot

Each monolith depot consists mainly of three different components specially harmonised components:

  • The accumulator core 

    This represents the first storage unit and ensures a high degree of efficiency

  • Steel casing
    This assures good insulation and durability

  • Natural stone casing
    This serves as the second storage unit and the visible aspect


The sophisticated design and combination of these elements delivers an enormous storage mass, and consequently also outstanding storage effect and very high efficiency.


The exceptional storage mass of the monolith depot means that heat energy is radiated for a long time The result: Many hours of radiated heat without recharging. In comparison: In a steel fireplace, wood must be added much more frequently, because its storage mass is smaller. The constant heating and cooling leads to more pronounced temperature fluctuations – with the monolith depot, the room temperature is more constant.

Heating cycle pattern of the monolith depot compared with a steel fireplace

Heating cycle pattern of the monolith depot5

Heating cycle pattern of the steel fireplace5

The entire accumulator core consists of heavily compressed accumulator refractory clay system elements. The formulation of the refractory clay is adapted specifically to the requirements of the monolith depot. During the manufacturing process, this special refractory clay material is compressed into the shaped parts under extremely high pressure and then fired.

The monolith depot models in overview

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. 3Test according to DIN 152504. The weight dimension does not reflect the ratio of individual dimensions to each other. Materials used: Calcium silicate insulation panel, lightweight concrete, extruded potter's clay, kiln ceramic, dry-pressed refractory clay, Nero Assoluto natural stone. 5The diagram serves only to illustrate heat emission and heating cycles, it does not represent an actual correlation of time, temperature and heating cycle (steel fireplace without additional accumulator). 6Test according to DIN EN 13240. 7 Test according to DIN EN 15250. 8Weight information relates to a natural stone facing of stone type Nero Roma.

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.