Heating and hot water supply apparatus

A heating and hot water supply apparatus comprising:

• a heating device configured to heat a heat transfer medium;
• a heating circulation path for circulating the heat transfer medium heated by the heating device to and from a heating terminal;
• a heat exchanger for hot water supply including a primary-side path and a secondary-side path for heat exchange;
• a hot water supply path which branches from the heating circulation path and through which the heat transfer medium flows through the primary-side path of the heat exchanger for hot water supply without passing through the heating terminal and then joins the heating circulation path again;
• a distribution control device configured to control a distribution ratio which is a ratio of a flow rate of a heat transfer medium supplied to the hot water supply path to a total flow rate of the heat transfer medium heated by the heating device;
• a water inlet pipe that is connected to an input side of the secondary-side path;
• a hot water delivery pipe that is connected to an output side of the secondary-side path;
• a bypass path through which low temperature water introduced into the water inlet pipe is guided to the hot water delivery pipe without passing through the secondary-side path;
• a bypass control device configured to control a bypass ratio which is a ratio of a flow rate of low temperature water introduced into the bypass path to a total flow rate of low temperature water introduced into the water inlet pipe;
• a hot water supply port that is connected downstream from a connection point with the bypass path in the hot water delivery pipe;
• a first temperature detector configured to detect a temperature of low temperature water introduced into the water inlet pipe;
• a second temperature detector that is arranged upstream from the connection point in the hot water delivery pipe and configured to detect a temperature of high temperature water heated along the secondary-side path;
• a third temperature detector that is arranged downstream from the connection point in the hot water delivery pipe and configured to detect a hot water temperature from the hot water supply port;
• and
• a control unit configured to regulate the bypass ratio by using the bypass control device so as to control the hot water temperature to a hot water target temperature on the basis of detection values of the first to third temperature detectors,
• wherein the control unit controls the distribution control device so that, during a simultaneous operation of heating and hot water supply, when the bypass ratio is lowered, the distribution ratio is increased, and when the bypass ratio is increased, the distribution ratio is decreased, and
• wherein the control unit
• i) calculates a reference temperature of the high temperature water when the hot water temperature reaches the hot water target temperature in presence of a temperature of the low temperature water detected by the first temperature detector, while the bypass ratio is a predetermined reference value, and
• ii) increases the distribution ratio when a temperature of the high temperature water detected by the second temperature detector is lower than the reference temperature.