The invention relates to a central
heating system (1) with at least one primary heat source (2) that can be operated with the aid of fuels, with at least one electrically operated
heat pump (3), with at least one water-to-air
heat exchanger (4) and with at least one domestic
hot water storage tank (5) for
intermediate storage of domestic hot water (11), wherein a
heat exchanger inlet line (L) WT, zu ) of the
piping system (7) is fluidically connected on the one hand to the primary heat source (2) and on the other hand to the water-air
heat exchanger (4), wherein a
heat pump drain line (L WP, ab ) of the
piping system (7) is fluidically connected on the one hand to the
heat pump (3) and on the other hand to the primary heat source (2), and a method for operating and / or controlling and / or regulating such a central
heating system (1). In particular, the demand for fuel for the
primary energy source (2) is minimized over the year by installing a - first - 3 / 2-way valve (21.1) in the heat exchanger inlet line (L WT, zu ) is arranged, wherein a - first - 3-way connector (26.1) is located in the heat pump drain line (L WP, ab ) is arranged so that a
branch flow circuit (K) is formed by means of a
branch of the 3 / 2-way valve (21.1) and a
branch of the 3-way connector (26.1). AB ) of the
piping system (7) is formed, wherein the
heat transfer fluid (6) is circulated through the branch circuit (K) by means of at least one pump (8, 9, 9b) AB ) is eligible for funding and with the help of the branch circuit (K AB ) flowing
heat transfer fluids (6) the domestic hot water (11) can be heated.