During the active period of Rauna Castle use, it was heated with stoves. It is evidenced by several smoke channel sites preserved in the walls of the castle, which had been built inside. Fireplaces or stoves were placed in the corners of the premises and were connected to the masonry wall on two sides. Multiple evidence on the use of stoves and fireplaces have been collected during archaeological research, where fragments of glazed tiles have been found and, in one case, the restoration of a stove tile to the condition that demonstrates how it looked in the 17th century was successful. Archaeological research was not performed at the first floor and cellar of the main blocks of the castle, therefore it cannot be stated exactly that the main premises of the second floor of Rauna Castle were heated by using hypocaust heating system typical of Middle Ages. Presumably, such system could have existed, because traces of smoke channels are seen in the walls of the main blocks, which proceed from the cellar to the level of the third floor. The hypocaust system was operated by means of the stove that was built on the utility floor and there was a separate chamber over it, which was filled with boulders. When fire was built in the stove, the boulders heated up and the heat from them, through separate channels, entered the premises built on upper levels and, through hatches in the floors, heated them.