The residual moisture content of the paper web is removed by steam-heated cylinders in the drying section of the paper machine. The drying process removes heat from the steam, which then forms a thin layer of condensate on the inner walls of the cylinder. This layer influences the transfer of heat to the paper and has to be skimmed off continuously by siphoning. The correct level of heat transfer from the drying cylinder to the paper is monitored by pressure measurements both at the inlet and at the outlet.