Heating and hot water supply system

Abstract

A heating and hot water supply system is provided and includes at least a distribution unit, a hot water supply heat exchanger and a flow rate adjusting unit. The distribution unit adjusts a distribution ratio capable of handling operations including heating, hot water supply and simultaneous heating and hot water supply operations. When the hot water supply operation starts, first hot water supply control, which adjusting a temperature to a hot water supply set temperature by the flow rate adjusting unit, is performed. After supplying the hot water having the hot water supply set temperature according to the first hot water supply control is maintained for a reference time or longer, transition to second hot water supply control, which a tapping water temperature of the hot water supply heat exchanger is brought close to the hot water supply set temperature, and a mixing amount of clean water reduced, is performed.

What is claimed is: 
     
         1 . A heating and hot water supply system, comprising:
 a combustion unit;   a heat exchanger that heats a heat medium with combustion heat of the combustion unit;   a heat medium circulation passage that connects the heat exchanger to an external heating terminal;   a circulation pump that is disposed in the circulation passage;   a bypass passage that branches from the circulation passage to bypass the external heating terminal;   a hot water supply heat exchanger that is disposed in the bypass passage;   a water supply passage through which clean water is supplied to the hot water supply heat exchanger; and   a hot water supply passage through which hot water heated by the hot water supply heat exchanger is supplied;   a distribution unit that is provided at a branch section of the bypass passage;   a hot water supply bypass passage that branches from the water supply passage and connected to the hot water supply passage; and   a flow rate adjusting unit that adjusts a bypass flow rate of the hot water supply bypass passage,   wherein the distribution unit is able to adjust a distribution ratio to be able to handle operations including a heating operation, a hot water supply operation, and a simultaneous heating and hot water supply operation, and   when the hot water supply operation starts, a first hot water supply control, which adjusts to a hot water supply set temperature by adjusting the flow rate adjusting unit to mix the clean water with the hot water heated by the hot water supply heat exchanger, is performed, and   when supply of the hot water having the hot water supply set temperature according to the first hot water supply control has been maintained for a preset reference time or longer, transition to a second hot water supply control, which a tapping water temperature of the hot water heated by the hot water supply heat exchanger is brought close to the hot water supply set temperature and a mixing amount of the clean water is reduced, is performed.   
     
     
         2 . The heating and hot water supply system according to  claim 1 ,
 wherein, when the second hot water supply control is performed, if a hot water supply flow rate changes, transition to the first hot water supply control is performed.