Biomass heating system for firing biogenic fuel, comprising: a boiler having a combustion device and having a heat exchanger; a controller having a memory; at least one sensor (76, 259) capable of detecting a state of an ash removal device (7, 25) for cleaning combustion residues from the boiler; wherein the biomass heating system is set up such that the control device can detect a blockage of the ash removal device (7, 25) by means of information received from the sensor (76, 259), the biomass heating system further comprising: a boiler with a combustion device and with a heat exchanger, wherein the combustion device comprises a rotary grate with at least one rotary grate element (252, 253, 254) rotatably mounted with an axis of rotation, wherein the rotary grate can be rotated in order to clean the combustion residues from the combustion surface of the rotary grate; at least one rotation angle sensor as the sensor, which can detect a rotation angle of the rotation axis and which is communicatively connected to the control device; at least one drive for rotating the axis of rotation, wherein the drive is controlled by the control device; wherein the biomass heating system is configured to detect a blockage of a rotation of the at least one rotary grate element (252, 253, 254) if a certain rotational speed of the at least one rotary grate element (252, 253, 254) is smaller than a predetermined threshold value (Sd). a boiler having a combustion device and having a heat exchanger; a controller having a memory; at least one sensor (76, 259) capable of detecting a state of an ash removal device (7, 25) for cleaning combustion residues from the boiler; wherein the biomass heating system is set up such that the control device can detect a blockage of the ash removal device (7, 25) by means of information received from the sensor (76, 259), the biomass heating system further comprising: a boiler with a combustion device and with a heat exchanger, wherein the combustion device comprises a rotary grate with at least one rotary grate element (252, 253, 254) rotatably mounted with an axis of rotation, wherein the rotary grate can be rotated in order to clean the combustion residues from the combustion surface of the rotary grate; at least one rotation angle sensor as the sensor, which can detect a rotation angle of the rotation axis and which is communicatively connected to the control device; at least one drive for rotating the axis of rotation, wherein the drive is controlled by the control device; wherein the biomass heating system is configured to detect a blockage of a rotation of the at least one rotary grate element (252, 253, 254) if a certain rotational speed of the at least one rotary grate element (252, 253, 254) is smaller than a predetermined threshold value (Sd). a boiler with a combustion device and with a heat exchanger, wherein the combustion device comprises a rotary grate with at least one rotary grate element (252, 253, 254) rotatably mounted with an axis of rotation, wherein the rotary grate can be rotated in order to clean the combustion residues from the combustion surface of the rotary grate; at least one rotation angle sensor as the sensor, which can detect a rotation angle of the rotation axis and which is communicatively connected to the control device; at least one drive for rotating the axis of rotation, wherein the drive is controlled by the control device; wherein the biomass heating system is configured to detect a blockage of a rotation of the at least one rotary grate element (252, 253, 254) if a certain rotational speed of the at least one rotary grate element (252, 253, 254) is smaller than a predetermined threshold value (Sd).