Water heating system including multi-function heat source apparatus
When a hot water supply operation is started, a single mode is used in which hot water is output only from a second hot water supply circuit of a water heater, by cut-off of a flow path in a first hot water supply circuit of a space-heating water heater by a cut-off mechanism. When a load imposed by hot water supply by the second hot water supply circuit increases during the hot water supply operation in the single mode, the cut-off mechanism is opened to start hot water output from the first hot water supply circuit and a hot water supply operation in a parallel mode is performed in which hot water is output from both of the first hot water supply circuit and the second hot water supply circuit.
1. A water heating system comprising:
a first heat source apparatus, the first heat source apparatus being a hot-water-heating heat source apparatus and including a first hot water supply circuit;
a second heat source apparatus including a second hot water supply circuit;
a hot water delivery pipe to which the first and second hot water supply circuits are connected in parallel; and
a cut-off mechanism configured to cut off a flow path to the hot water delivery pipe in the first hot water supply circuit,
the first heat source apparatus having an operation state in which heating of low-temperature water in the first hot water supply circuit and supply of a heat medium to a space-heating terminal are simultaneously performed by using a common heat source,
the first hot water supply circuit being configured to heat the low-temperature water through heat exchange with the heat medium, which is heated through heat exchange with the heat generated by burning fuel, and to output the heated water to the hot water delivery pipe,
the second hot water supply circuit being configured to heat low-temperature water through heat exchange with the heat generated by burning fuel, and to output the heated water to the hot water delivery pipe,
when hot water supply by the water heating system is started, hot water being output to the hot water delivery pipe from the second hot water supply circuit while the flow path in the first hot water supply circuit is cut off by the cut-off mechanism, and
when a load imposed by hot water supply by the second hot water supply circuit becomes higher than a predetermined reference value, the cut-off mechanism opening the flow path in the first hot water supply circuit to allow output of hot water from both of the first and second hot water supply circuits to the hot water delivery pipe, wherein
the first heat source apparatus includes
a first heating mechanism configured to heat the heat medium,
a space-heating circulation path configured to circulate the heat medium heated by the first heating mechanism to and from the space-heating terminal during a space-heating operation,
a bypass circulation path branched from the space-heating circulation path and configured such that the heat medium is again merged with the space-heating circulation path without going through the space-heating terminal, and
a distribution control mechanism configured to control a distribution ratio representing a ratio of a flow rate of the heat medium supplied to the bypass circulation path to a total flow rate of the heat medium heated by the first heating mechanism,
the first hot water supply circuit is configured to heat at least some of the low-temperature water which flows through the first hot water supply circuit through heat exchange with the heat medium which flows through the bypass circulation path,
the second hot water supply circuit includes a second heating mechanism configured to heat at least some of the low-temperature water which flows through the second hot water supply circuit,
when the hot water supply is started, the second heating mechanism is activated with the flow path in the first hot water supply circuit being cut off by the cut-off mechanism,
when the load imposed by hot water supply by the second hot water supply circuit becomes higher than the reference value, the distribution control mechanism is controlled such that some of the heat medium passes through the bypass circulation path in the first heat source apparatus and the cut-off mechanism opens the flow path in the first hot water supply circuit, and
when transition from a state that hot water is output only from the second hot water supply circuit to the hot water delivery pipe while the first heating mechanism is turned off to a state that hot water is output from both of the first and second hot water supply circuits to the hot water delivery pipe is made, the cut-off mechanism opens the flow path in the first hot water supply circuit after a temperature of the heat medium supplied to the bypass circulation path becomes higher than a predetermined reference temperature by activation of the first heating mechanism.
2. The water heating system according to claim 1 , wherein
when an integrated value of amounts of flow in the first hot water supply circuit is smaller than a criterion value, control for the cut-off mechanism to forcibly open the flow path in the first hot water supply circuit is carried out every prescribed time.
3. The water heating system according to claim 2 , wherein
the first hot water supply circuit further includes a flow rate regulation mechanism configured to restrict an amount of flow in the first hot water supply circuit, and
the flow rate regulation mechanism restricts the amount of flow to a predetermined level when the cut-off mechanism forcibly opens the flow path in the first hot water supply circuit based on the integrated value.
4. The water heating system according to claim 1 , wherein
the first hot water supply circuit includes a flow rate restriction unit configured to make an amount of flow in the first hot water supply circuit smaller than an amount of flow in the second hot water supply circuit when hot water is output from both of the first and second hot water supply circuits to the hot water delivery pipe.
5. The water heating system according to claim 4 , wherein
the flow rate restriction unit includes a flow rate regulation valve configured to restrict the amount of flow in the first hot water supply circuit, and
a control range upper limit value of a valve opening of the flow rate regulation valve when hot water is output from both of the first and second hot water supply circuits to the hot water delivery pipe is set such that the amount of flow in the first hot water supply circuit at the control range upper limit value is smaller than the amount of flow in the second hot water supply circuit.
6. The water heating system according to claim 4 , wherein
the flow rate restriction unit includes a mechanism configured to increase a flow path resistance in the first hot water supply circuit.
7. The water heating system according to claim 1 , wherein
when a flow rate in the first hot water supply circuit is lower than a prescribed value while a control command to open the flow path is generated for the cut-off mechanism, a closing failure of the cut-off mechanism is sensed only when a flow rate state in the second hot water supply circuit satisfies a predetermined flow rate condition.
8. The water heating system according to claim 1 , wherein
the second heat source apparatus is a water heater dedicated for hot water supply.
9. A water heating system comprising:
a first heat source apparatus, the first heat source apparatus being a hot-water-heating heat source apparatus and including a first hot water supply circuit;
a second heat source apparatus including a second hot water supply circuit;
a hot water delivery pipe to which the first and second hot water supply circuits are connected in parallel; and
a cut-off mechanism configured to cut off a flow path to the hot water delivery pipe in the first hot water supply circuit,
the first heat source apparatus having an operation state in which heating of low-temperature water in the first hot water supply circuit and supply of a heat medium to a space-heating terminal are simultaneously performed by using a common heat source,
the first hot water supply circuit being configured to heat the low-temperature water through heat exchange with the heat medium, which is heated through heat exchange with the heat generated by burning fuel, and to output the heated water to the hot water delivery pipe,
the second hot water supply circuit being configured to heat low-temperature water through heat exchange with the heat generated by burning fuel, and to output the heated water to the hot water delivery pipe,
when hot water supply by the water heating system is started, hot water being output to the hot water delivery pipe from the second hot water supply circuit while the flow path in the first hot water supply circuit is cut off by the cut-off mechanism, and
when a load imposed by hot water supply by the second hot water supply circuit becomes higher than a predetermined reference value, the cut-off mechanism opening the flow path in the first hot water supply circuit to allow output of hot water from both of the first and second hot water supply circuits to the hot water delivery pipe, wherein
the first heat source apparatus includes
a first heating mechanism configured to heat the heat medium,
a space-heating circulation path configured to circulate the heat medium heated by the first heating mechanism to and from the space-heating terminal during a space-heating operation,
a bypass circulation path branched from the space-heating circulation path and configured such that the heat medium is again merged with the space-heating circulation path without going through the space-heating terminal, and
a distribution control mechanism configured to control a distribution ratio representing a ratio of a flow rate of the heat medium supplied to the bypass circulation path to a total flow rate of the heat medium heated by the first heating mechanism,
the first hot water supply circuit is configured to heat at least some of the low-temperature water which flows through the first hot water supply circuit through heat exchange with the heat medium which flows through the bypass circulation path,
the second hot water supply circuit includes a second heating mechanism configured to heat at least some of the low-temperature water which flows through the second hot water supply circuit,
when the hot water supply is started, the second heating mechanism is activated with the flow path in the first hot water supply circuit being cut off by the cut-off mechanism,
when the load imposed by hot water supply by the second hot water supply circuit becomes higher than the reference value, the distribution control mechanism is controlled such that some of the heat medium passes through the bypass circulation path in the first heat source apparatus and the cut-off mechanism opens the flow path in the first hot water supply circuit, and
when a flow rate in the first hot water supply circuit is higher than a prescribed value while a control command to cut off the flow path is generated for the cut-off mechanism, the distribution control mechanism controls the distribution ratio such that the heat medium is not supplied to the bypass circulation path.
10. The water heating system according to claim 1 , wherein
when an integrated value of amounts of flow in the first hot water supply circuit is smaller than a criterion value, control for the cut-off mechanism to forcibly open the flow path in the first hot water supply circuit is carried out every prescribed time.
11. The water heating system according to claim 10 , wherein
the first hot water supply circuit further includes a flow rate regulation mechanism configured to restrict an amount of flow in the first hot water supply circuit, and
the flow rate regulation mechanism restricts the amount of flow to a predetermined level when the cut-off mechanism forcibly opens the flow path in the first hot water supply circuit based on the integrated value.
12. A water heating system comprising:
a first heat source apparatus, the first heat source apparatus being a hot-water-heating heat source apparatus and including a first hot water supply circuit;
a second heat source apparatus including a second hot water supply circuit;
a hot water delivery pipe to which the first and second hot water supply circuits are connected in parallel; and
a cut-off mechanism configured to cut off a flow path to the hot water delivery pipe in the first hot water supply circuit,
the first heat source apparatus having an operation state in which heating of low-temperature water in the first hot water supply circuit and supply of a heat medium to a space-heating terminal are simultaneously performed by using a common heat source,
the first hot water supply circuit being configured to heat the low-temperature water through heat exchange with the heat medium, which is heated through heat exchange with the heat generated by burning fuel, and to output the heated water to the hot water delivery pipe,
the second hot water supply circuit being configured to heat low-temperature water through heat exchange with the heat generated by burning fuel, and to output the heated water to the hot water delivery pipe,
when hot water supply by the water heating system is started, hot water being output to the hot water delivery pipe from the second hot water supply circuit while the flow path in the first hot water supply circuit is cut off by the cut-off mechanism, and
when a load imposed by hot water supply by the second hot water supply circuit becomes higher than a predetermined reference value, the cut-off mechanism opening the flow path in the first hot water supply circuit to allow output of hot water from both of the first and second hot water supply circuits to the hot water delivery pipe, wherein
the first heat source apparatus includes
a first heating mechanism configured to heat the heat medium,
a space-heating circulation path configured to circulate the heat medium heated by the first heating mechanism to and from the space-heating terminal during a space-heating operation,
a bypass circulation path branched from the space-heating circulation path and configured such that the heat medium is again merged with the space-heating circulation path without going through the space-heating terminal, and
a distribution control mechanism configured to control a distribution ratio representing a ratio of a flow rate of the heat medium supplied to the bypass circulation path to a total flow rate of the heat medium heated by the first heating mechanism,
the first hot water supply circuit is configured to heat at least some of the low-temperature water which flows through the first hot water supply circuit through heat exchange with the heat medium which flows through the bypass circulation path,
the second hot water supply circuit includes a second heating mechanism configured to heat at least some of the low-temperature water which flows through the second hot water supply circuit,
when the hot water supply is started, the second heating mechanism is activated with the flow path in the first hot water supply circuit being cut off by the cut-off mechanism,
when the load imposed by hot water supply by the second hot water supply circuit becomes higher than the reference value, the distribution control mechanism is controlled such that some of the heat medium passes through the bypass circulation path in the first heat source apparatus and the cut-off mechanism opens the flow path in the first hot water supply circuit, and
the first hot water supply circuit includes a flow rate restriction unit configured to make an amount of flow in the first hot water supply circuit smaller than an amount of flow in the second hot water supply circuit when hot water is output from both of the first and second hot water supply circuits to the hot water delivery pipe.
13. The water heating system according to claim 12 , wherein
the flow rate restriction unit includes a flow rate regulation valve configured to restrict the amount of flow in the first hot water supply circuit, and
a control range upper limit value of a valve opening of the flow rate regulation valve when hot water is output from both of the first and second hot water supply circuits to the hot water delivery pipe is set such that the amount of flow in the first hot water supply circuit at the control range upper limit value is smaller than the amount of flow in the second hot water supply circuit.
14. The water heating system according to claim 12 , wherein
the flow rate restriction unit includes a mechanism configured to increase a flow path resistance in the first hot water supply circuit.
15. The water heating system according to claim 1 , wherein
when a flow rate in the first hot water supply circuit is lower than a prescribed value while a control command to open the flow path is generated for the cut-off mechanism, a closing failure of the cut-off mechanism is sensed only when a flow rate state in the second hot water supply circuit satisfies a predetermined flow rate condition.
16. The water heating system according to claim 1 , wherein
the second heat source apparatus is a water heater dedicated for hot water supply.