Method for operating a circulation system having a temperature control device with an input port and an output port for controlling the temperature of water and having a pipe system with a plurality of lines which have one or more part sections provided with a heat coupling to a surrounding environment and are connected by means of nodes, wherein one or more of the pipes of the pipe system are configured as a feed pipe , at least one individual supply pipe connected to a tapping point and at least one pipe configured as a circulation pipe is connected to the feed pipe or pipes , comprising the steps - setting a water temperature at the output port to a value T a by means of the temperature control device - setting a volume flow at the input port to a value V z characterized by the following steps - determining, in particular calculating, a change in temperature of the water between the initial region and end region according to a model of the axial temperature change for the first part section connected to the output port, starting from a temperature start value T MA * and a volume flow start value V z *, - determining, in particular calculating, a temperature change of the water between the initial region and end region for each further given part section according to the temperature change model, under the condition that the water temperature in the initial region of the given part section is equal to the water temperature in the end region of the part section to which the given part section is connected, and - selecting the value T a of the water temperature and the value V z of the volume flow at the output port, such that in the end region of each part section the water temperature TME is within a predetermined temperature range around T soll , in particular the water temperature T b < T soll with T soll -T b < θ is set at the input port, wherein θ>0 is a predetermined value, and the temperature control device is connected with its input port to the circulation pipe and via a pipe to a water supply or a device is provided for cooling water , which is connected via a pipe with an input port to a water supply , wherein the circulation pipe is connected downstream of an output port of the device . - setting a water temperature at the output port to a value T a by means of the temperature control device - setting a volume flow at the input port to a value V z - determining, in particular calculating, a change in temperature of the water between the initial region and end region according to a model of the axial temperature change for the first part section connected to the output port, starting from a temperature start value T MA * and a volume flow start value V z *, - determining, in particular calculating, a temperature change of the water between the initial region and end region for each further given part section according to the temperature change model, under the condition that the water temperature in the initial region of the given part section is equal to the water temperature in the end region of the part section to which the given part section is connected, and - selecting the value T a of the water temperature and the value V z of the volume flow at the output port, such that in the end region of each part section the water temperature TME is within a predetermined temperature range around T soll , in particular the water temperature T b < T soll with T soll -T b < θ is set at the input port, wherein θ>0 is a predetermined value, and the temperature control device is connected with its input port to the circulation pipe and via a pipe to a water supply or a device is provided for cooling water , which is connected via a pipe with an input port to a water supply , wherein the circulation pipe is connected downstream of an output port of the device . <EOS>