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 capable of detecting a state of an ash removal device 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 by means of information received from the sensor , 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 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 (S118) a blockage of a rotation of the at least one rotary grate element if a certain rotational speed of the at least one rotary grate element 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 capable of detecting a state of an ash removal device 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 by means of information received from the sensor , 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 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 (S118) a blockage of a rotation of the at least one rotary grate element if a certain rotational speed of the at least one rotary grate element 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 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 (S118) a blockage of a rotation of the at least one rotary grate element if a certain rotational speed of the at least one rotary grate element is smaller than a predetermined threshold value (Sd). <EOS>