Operating mode

There are two ways to transfer heat

  • Via warm ambient air
  • Via heat radiation

Modern warm water heating systems work with low flow temperatures. This concerns condensing boiler technology as well as solar heating systems. The radiators are heated up to temperatures between 50 and 60° C.
Flow temperatures of underfloor heatings are clearly lower. The warm air rises from the radiant surfaces to the ceiling, cools down at the walls and windows and falls down to the floor. From there, it goes back to the radiator where it is heated up again. With an underfloor heating the air rises to the ceiling and is cooled down at the walls. On the floor it is heated up again.
Both systems make circulate the air by convection.
Because of the little thermal proportion, radiation heating systems like the astra natural stone heating barely produce air circulation. The natural stone heating works with higher temperatures, like a “tile stove”. The infrared radiation effect increases with the temperature. Objects in reach are heated directly because the effect of infrared heat is comparable to solar radiation.
Walls, ceiling, floor and furniture are heated up by the irradiation. Differences in temperature and air circulation are little. Thus you feel comfortable yet at a temperature that is approximately 3° C lower than with convectional heating. The whole structure of the building is heated evenly. This also prevents possible humidity penetration of the walls in old buildings. Humid walls are 'thermal bridges'.





Konvektionsstrom bei konventionellen HeizsystemenConvective air flow with conventional heating systems


Langwellige Wärmestrahlung bei der astra NatursteinheizungLong waved infrared radiation with an astra natural stone heating