Method for regulating a heating device for heating a fluid for a dialysis fluid circuity, control device and blood treatment apparatus

A method for regulating and/or for monitoring a heating device for heating a fluid that has flowed and/or is flowing, via an inlet, into an in-flow section of a dialysis fluid circuit, wherein the dialysis fluid circuit is part of a blood treatment apparatus, wherein the dialysis fluid circuit comprises a container for receiving the fluid, and a heating container for heating the fluid, the method comprising:

• determining a filling level of the fluid in the container;
• and
• in response to determining that the filling level of the fluid in the container has reached a pre-determined filling level value, starting a heating process for heating the fluid in the heating container, which is in fluid communication with the container by the inlet, wherein the heating process is started only when the filling level of the fluid in the container is determined to have reached the pre-determined filling level value.