CN108474587B

CN108474587B - Boiler for heating and water heating and control method thereof

Info

Publication number: CN108474587B
Application number: CN201680076160.1A
Authority: CN
Inventors: 许昌会; 金正谦
Original assignee: Kyungdong Navien Co Ltd
Current assignee: Kyungdong Navien Co Ltd
Priority date: 2015-12-23
Filing date: 2016-12-09
Publication date: 2021-01-29
Anticipated expiration: 2036-12-09
Also published as: RU2018126766A3; KR20170075235A; RU2723274C2; KR101831804B1; RU2018126766A; WO2017111364A1; CN108474587A

Abstract

The invention aims to provide a heating and water heating boiler and a control method thereof, wherein the boiler comprises the following components: it is possible to reduce a hot water temperature deviation when using hot water and to reduce the number of times of turning on/off the heater to prevent a life of the relay from being shortened. The heating and water heating boiler for achieving the above object includes: a first heat exchanger generating heated supply water; a second heat exchanger generating hot water by heat exchange between the supply water supplied from the first heat exchanger and the direct water; a flow rate adjusting valve for adjusting a circulation flow rate of the supply water circulated through the second heat exchanger in a hot water mode; and a control unit which calculates a required heat amount corresponding to a set hot water temperature of a user in a hot water mode, sets the supply heat amount supplied from the first heat exchanger to correspond to the required heat amount, and adjusts the opening degree of the flow rate adjustment valve so that the circulation flow rate corresponds to the required heat amount in the hot water mode.

Description

Boiler for heating and water heating and control method thereof

Technical Field

The present invention relates to a heating and water heating boiler and a control method thereof, and more particularly, to a heating and water heating boiler and a control method thereof capable of reducing a temperature deviation of hot water when hot water is used in the heating and water heating boiler.

Background

In general, a boiler capable of using both heating and hot water is operated in a heating mode in which heating water heated by a heat exchanger is supplied to a place where heating is needed; the hot water mode is a mode in which the heating water heated by the heat exchanger is supplied to the hot water supply heat exchanger.

Fig. 1 is a diagram showing a structure of a conventional heating and water heating boiler.

The heating and water heating boiler includes: a first heat exchanger 10 for heating supply water; an expansion water tank 20 storing supply water; a second heat exchanger 40 for heating the direct water supply to supply hot water to the user; a three-way valve 30 for supplying the supply water heated at the first heat exchanger 10 to any one of a heating demand (not shown) and a second heat exchanger 40; and a circulation pump 50 for circulating water passing through the heating demand or the second heat exchanger 40.

The supply water heated in the first heat exchanger 10 in the heating mode is supplied to a heating demand through the third supply pipe 83 after passing through the first supply pipe 81, the expansion water tank 20, the second supply pipe 82, and the three-way valve 30. The supply water after heat exchange at the heating demand is circulated to the first heat exchanger 10 through the first and second

water return pipes

84 and 88.

In the hot water mode, the supply water heated in the first heat exchanger 10 flows into the second heat exchanger 40 through the hot water side supply pipe 85 after passing through the first supply pipe 81, the expansion tank 20, the second supply pipe 82, and the three-way valve 30. In the second heat exchanger 40, heat exchange is performed between the direct-fed water flowing in through the direct-fed water inflow pipe 86 and the supplied water flowing in through the hot water side supply pipe 85, and the direct-fed water is changed into hot water and supplied to the user through the hot water outlet pipe 87. The return water having a temperature decreased by heat exchange in the second heat exchanger 40 is circulated to the first heat exchanger 10 through the hot water side return pipe 89 and the second return pipe 88.

Unexplained reference numerals

60 and 70 denote a check valve and a flow sensor, respectively.

In the case of using hot water, it is important to reduce the variation in the hot water temperature of the outlet water when the flow rate of the direct water supply changes or the set temperature of the hot water changes, but the conventional boiler for heating and heating water described above has the following problems.

First, in the system in which the heat quantity control speed by the first heat exchanger 10 is slow, the temperature change speed of the supply water supplied from the first heat exchanger 10 is also slow, and accordingly, the hot water temperature change speed of the outlet water heated by the second heat exchanger 40 is also slow, and there is a problem that the deviation of the hot water temperature becomes large when the hot water set temperature is changed.

Second, when the heating and water heating boiler is an electric boiler, the amount of heat supplied to the first heat exchanger 10 cannot be controlled in proportion, and thus the temperature deviation becomes large. That is, the first heat exchanger 10 at the electric boiler is equipped with a plurality of

heaters

11, 12, 13, and each of the

heaters

11, 12, 13 can supply only a fixed amount of heat. For example, assuming that the amount of heat supplied by one heater 11 is 8,000kcal/h, if two heaters are turned On (On), 16,000kcal/h is supplied, and if all three

heaters

11, 12, 13 are turned On (On), 24,000kcal/h is supplied. The above-mentioned amount of heat supplied is determined to three fixed values, and thus it is impossible to supply between 8,000 and 16,000 heat and between 16,000 and 24,000 heat. Therefore, only a higher or lower amount of heat than required can be supplied according to the hot water temperature set by the user. Since the

heaters

11, 12, and 13 can supply only a fixed amount of heat, the process of turning Off (Off) the

heaters

11, 12, and 13 if the temperature of hot water supplied through the hot water outlet pipe 87 reaches the hot water temperature set by the user, and then turning On (On) the

heaters

11, 12, and 13 if the hot water temperature is again reduced to the set temperature or less is repeated. If the On/Off operation is repeated as described above, a problem arises in that the life of a relay (relay) for supplying power to the

heaters

11, 12, and 13 is shortened.

Third, in the heating operation, the temperature of the supply water supplied to the heating demand is usually maintained at a high temperature of at least 60 degrees. If the mode is switched to the hot water mode in the heating operation, the supply water of a high temperature immediately flows to the second heat exchanger 40 at the instant when the three-way valve 30 is switched. Therefore, before the hot water is cooled to the supply water temperature suitable for the hot water temperature set by the user, the hot water of the hot water is rapidly increased in temperature because the high-temperature supply water flows into the second heat exchanger 40, and thus there is a problem that the user may be scalded.

As a prior art related to the above heating and water heating boiler, korean laid-open patent No. 10-2008-0091637 "heating system using a heat exchanger of an instantaneous electric boiler" is disclosed.

Disclosure of Invention

Technical problem

The present invention has been made to solve all the above problems, and an object of the present invention is to provide a heating and water heating boiler and a control method thereof, the boiler including: when hot water is used, the deviation of the hot water temperature can be reduced, and the number of times of On/Off of the heater can be reduced, thereby preventing the service life of the relay from being shortened.

Technical scheme

The heating and water heating boiler according to the present invention for achieving the above object includes: a first heat exchanger 10 generating heated supply water; a second heat exchanger 40 generating hot water by heat exchange between the supply water supplied from the first heat exchanger 10 and the straight supply water; a flow rate adjustment valve 110 for adjusting a circulation flow rate of the supply water circulated through the second heat exchanger 40 in a hot water mode; and a control unit for calculating a required heat amount corresponding to a set hot water temperature of a user in a hot water mode, setting the supply heat amount supplied from the first heat exchanger 10 to correspond to the required heat amount, and adjusting the opening degree of the flow rate adjustment valve 110 to correspond the circulation flow rate to the required heat amount in the hot water mode.

The first heat exchanger 10 may include: the plurality of

heaters

11, 12, and 13 generate heat with a constant amount of heat by the supply of power.

The control portion may set the number of the

heaters

11, 12, 13 to be opened so that the supplied heat amount is higher than the required heat amount, and decrease the opening degree of the flow rate adjustment valve 110 in order to decrease the circulation flow rate to correspond to the required heat amount.

The heating and water heating boiler may include a feed water temperature sensor 120 for measuring a temperature of the feed water flowing into the second heat exchanger 40, and a return water temperature sensor 130 for measuring a temperature of the return water passing through the second heat exchanger 40, and the controller may calculate the circulation flow rate based on a temperature difference measured by the feed water temperature sensor 120 and the return water temperature sensor 130 and the required heat amount.

The flow rate adjustment valve 110 may be provided on the hot water side return pipe 89 connected to the outlet side of the second heat exchanger 40.

In the method for controlling a heating and water heating boiler according to the present invention, the heating and water heating boiler includes: a first heat exchanger 10 generating heated supply water; a second heat exchanger 40 for generating hot water by heat exchange between the heating water supplied from the first heat exchanger 10 and the direct water; a control unit for controlling the amount of heat supplied from the first heat exchanger 10 according to a required amount of heat corresponding to a set hot water temperature of a user in a hot water mode, the method comprising: a) sensing a flow rate of the direct supply water, thereby sensing a hot water usage of a user; b) in the control part, a required heat amount is calculated corresponding to a set hot water temperature set by a user, and a supply heat amount supplied from the first heat exchanger 10 is set corresponding to the calculated required heat amount; c) supplying a predetermined amount of the supply heat to the supply water to heat the supply water, and circulating the heated supply water to the first heat exchanger 10 through the second heat exchanger 40; d) in a state where the supply heat amount is fixed, the circulation flow rate of the supply water passing through the second heat exchanger 40 is adjusted by the flow rate adjustment valve 110.

The first heat exchanger 10 may include a plurality of

heaters

11, 12, 13 generating heat according to power supply, and in the b) step, the control part sets the number of the

heaters

11, 12, 13 being turned on in such a manner that the supply heat amount is higher than the required heat amount; in the step d), the opening degree of the flow rate adjustment valve 110 is decreased so that the circulation flow rate corresponds to the required heat amount.

After the step d), the temperature of the supply water flowing into the second heat exchanger 40 may be measured by a supply water temperature sensor 120, and the

heaters

11, 12, 13 may be turned off in case the measured temperature of the supply water exceeds the temperature set at the control part.

In the method, the temperature of the supply water flowing into the second heat exchanger 40 may be measured by a supply water temperature sensor 120, and in the d) step, if the measured temperature of the supply water varies beyond a set range, the opening degree of the flow rate adjustment valve 110 is adjusted.

The method may measure a supply water temperature of the supply water flowing into the second heat exchanger 40 and a return water temperature of the return water passing through the second heat exchanger 40 in the d) step, and the control part calculates the circulation flow rate according to a difference between the supply water temperature and the return water temperature and the required heat amount, and adjusts the opening degree of the flow rate adjustment valve 110 to correspond to the calculated circulation flow rate.

Advantageous effects

According to the present invention, since the flow rate control valve capable of controlling the flow rate of the supply water circulating through the second heat exchanger is provided, the amount of heat required to be supplied from the second heat exchanger to the direct supply water can be timely feedback-controlled, and thus the occurrence of the deviation of the hot water temperature can be minimized.

In addition, since the electric boiler can supply the temperature of the hot water required by the user by adjusting only the opening degree of the flow rate adjustment valve without turning Off (Off) the heater, it is possible to prevent the life of the relay for supplying the power to the heater from being shortened, and to reduce the maintenance cost.

In addition, even when the temperature of the supply water supplied to the second heat exchanger is rapidly changed, such as when switching to the hot water mode during heating operation, the amount of supply heat can be rapidly reduced by simply adjusting the opening degree of the flow rate adjustment valve, and scalding of the hot water user can be prevented.

Further, the user can flow only the flow rate required for the set hot water temperature, and thus the energy supplied from the heat exchanger can be reduced.

Drawings

Fig. 2 is a diagram showing a structure of a heating and water heating boiler according to the present invention.

Fig. 3 is a diagram showing a configuration of connection to a second heat exchanger in the heating and hot water combined boiler according to the present invention.

Fig. 4 is a flowchart illustrating a control method of a heating and water heating boiler according to the present invention.

Description of the symbols

10:

first heat exchangers

11, 12, 13: heating device

30: three-way valve 40: second heat exchanger

50: the circulation pump 60: check valve

70: the flow rate sensor 81: a first supply pipe

82: second supply pipe 83: third supply pipe

84: first water return pipe 85: hot water side supply pipe

86: direct water inflow pipe 87: hot water outlet pipe

88: second water return pipe 89: hot water side return pipe

110: flow regulating valve 120: water supply temperature sensor

130: return water temperature sensor 140: direct water supply temperature sensor

150: hot water temperature sensor

Detailed Description

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described with reference to the drawings.

The structure of the heating and water heating boiler according to the present invention will be described with reference to fig. 2.

The heating and water heating boiler according to the present invention includes: a first heat exchanger 10 for generating high-temperature supply water; a second heat exchanger 40 generating hot water by heat exchange between the supply water supplied from the first heat exchanger 10 and the direct supply water; a flow rate adjustment valve 110 for adjusting a flow rate of the supply water supplied to the second heat exchanger 40 in the hot water mode; and a control part for adjusting the opening of the flow regulating valve 110.

The first heat exchanger 10 is provided with a flow path through which the supply water flows and a heating unit for heating the supply water flowing through the flow path. The heating means may be a burner, but in the present embodiment, the

heaters

11, 12, and 13 are configured to be applied to an electric boiler and generate heat by power supply. Each of the

heaters

11, 12, and 13 is configured to supply a fixed amount of heat.

The supply water heated in the first heat exchanger 10 flows into the expansion tank 20 through the first supply pipe 81. Inside the expansion tank 20, the supply water is filled at a predetermined water level, and an empty space is formed at an upper portion of the filled supply water, so that the expanded volume can be absorbed in a case where the volume of the supply water becomes large due to a temperature increase.

The supply water discharged from the expansion tank 20 flows to the three-way valve 30 through the second supply pipe 82. The three-way valve 30 performs switching of the flow path direction as follows: in the heating mode, the supply water supplied through the second supply pipe 82 is supplied to a heating demand (not shown) through the third supply pipe 83, and in the hot water mode, the supply water is supplied to the second heat exchanger 40 through the hot water side supply pipe 85.

The temperature of the supply water heat-exchanged at the heating demand drops and flows to the first heat exchanger 10 through the first and second

water return pipes

84 and 88. The water flowing in the first and second

water return pipes

84 and 88 is referred to as "return water".

The second water return pipe 88 is provided with a circulation pump 50 for circulating water in a heating mode and a hot water mode.

The control part controls On/Off (On/Off) of the

heaters

11, 12, 13 to supply heat corresponding to the hot water temperature set by the user, and adjusts the opening degree of the flow rate adjustment valve 110 in order to flow only a flow rate required to supply hot water of the temperature set by the user to the second heat exchanger 40.

The structure connected to the second heat exchanger 40 will be described with reference to fig. 3.

To the second heat exchanger 40, there are connected: a direct feed water inflow pipe 86 into which the direct feed water flows; a hot water outlet pipe 87 for discharging the inflow direct water after being heated; a hot water side supply pipe 85 through which the supply water passing through the three-way valve 30 flows and flows into the second heat exchanger 40; the hot water side return pipe 89 flows supply water (hereinafter, referred to as "return water") having a temperature decreased by heat exchange in the second heat exchanger 40.

The direct-feed water inflow pipe 86 is provided with a flow rate sensor 70 and a direct-feed water temperature sensor 140. When the user uses hot water, the direct water flows into the direct water inflow pipe 86, and the flow of the direct water is sensed by the flow sensor 70, so that whether the user uses hot water can be sensed. And, based on the temperature of the direct supply water measured by the direct supply water temperature sensor 140, the control part calculates the amount of heat required for supplying hot water of the temperature required by the user.

A hot water temperature sensor 150 is provided on the hot water outlet pipe 87. The control part compares the hot water temperature measured by the hot water temperature sensor 150 with the hot water temperature set by the user, and adjusts the opening degree of the flow rate adjustment valve 110 according to the difference.

A supply water temperature sensor 120 for measuring the temperature of supply water flowing into the second heat exchanger 40 (hereinafter, referred to as "supply water temperature") is provided in the hot water side supply pipe 85, and a return water temperature sensor 130 for measuring the temperature of return water passing through the second heat exchanger 40 (hereinafter, referred to as "return water temperature") is provided in the hot water side return pipe 89.

The control unit calculates a circulation flow rate of the supply water circulated through the flow rate adjustment valve 110 from the temperature difference measured by the supply water temperature sensor 120 and the return water temperature sensor 130 and the required heat amount.

The flow rate control valve 110 is provided in a hot water side return pipe 89 as a pipe connected to the outlet side of the second heat exchanger 40. The flow rate control valve 110 may be provided in the hot water supply pipe 85, but since the supply water supplied from the first heat exchanger 10 has a high temperature, if the flow rate control valve 110 is provided in the hot water supply pipe 85, which is a pipe connected to the inlet side of the second heat exchanger 40, a problem of heat resistance may occur due to the high temperature supply water. Therefore, by providing the flow rate control valve 110 in the hot water side return pipe 89, it is possible to prevent a problem of deterioration in durability due to heat resistance.

Hereinafter, a method for controlling the heating and water heating boiler according to the present invention will be described with reference to fig. 4.

The user sets a desired hot water temperature (hereinafter, referred to as "set hot water temperature") by the operation unit, and starts using hot water.

When the user starts to use the hot water, the direct supply water flows into the direct supply water inflow pipe 86, and the boiler operates the hot water mode such that the flow of the direct supply water is sensed at the flow sensor 140.

In step S201, the flow rate value of the direct supply water sensed by the flow rate sensor 140 is input to the control part, and the control part determines that the user is using hot water through the input flow rate value.

If the control unit determines that the user is using hot water, the control unit calculates a required heat amount corresponding to the set hot water temperature set by the user in step S202.

Here, a mathematical expression for calculating the required heat amount is as follows.

[ mathematical formula 1]

Required heat quantity (kcal/h) × (set hot water temperature-direct water supply temperature) × direct water supply quantity × 60

In mathematical formula 1, the direct feed water temperature is the temperature of the direct feed water measured by the direct feed water temperature sensor 140, and the direct feed water flow rate is the flow rate of the direct feed water measured by the

flow sensor

140, and 60 denotes 60 minutes for calculating the heat amount per hour. For example, in the case where the hot water temperature is set to 40 ℃, the direct water temperature is set to 10 ℃, and the direct water flow rate is set to 10Lpm, the required amount of heat is 18,000 kcal/h.

After calculating the required amount of heat in step S203, the control portion sets the amount of heat required to be supplied from the first heat exchanger 10 to the supply water, and then turns On (On) the

heaters

11, 12, 13 according to the set amount of supply heat. For example, assuming that one heater 11 can supply 8,000kcal/h, if both

heaters

11, 12 are turned On (On), it is not enough to reach the required amount of heat, thus causing user dissatisfaction with respect to the hot water temperature. Therefore, in order to supply the required amount of heat, all of the three

heaters

11, 12, and 13 need to be turned On (On), and thus 24,000kcal/h higher than the required amount of heat, i.e., 18,000kcal/h, is set as the supply amount of heat.

In order to supply the supply heat to the supply water, the

heaters

11, 12, 13 and the circulation pump 50 are turned On (On). In this case, the opening and closing direction of the three-way valve 30 is set so that the supply water flows from the second supply pipe 82 to the hot water side supply pipe 85, and the flow rate adjustment valve 110 is in a state of being opened to the maximum.

In this state, the hot water mode is operated, and the control unit determines whether or not the temperature of the hot water measured from the hot water temperature sensor 150 has reached 40 ℃.

According to the determination result, if the hot water temperature reaches the set hot water temperature, step S205 is performed, otherwise, the process up to step S203 is continued.

If the hot water temperature reaches the set hot water temperature, a thermal equilibrium state is established between the supply water and the straight supply water passing through the second heat exchanger 40. If the required amount of heat is 18,000kcal/h and the circulation flow rate when the flow rate adjustment valve 110 is opened to the maximum is assumed to be 15.0Lpm, the temperature difference between the supply water temperature and the return water temperature in the thermal equilibrium state is 20 c according to equation 1. For example, the supply water temperature measured by the supply water temperature sensor 120 may be 60 ℃, and the return water temperature measured by the return water temperature sensor 130 may be 40 ℃.

In step S205, Feedback control is performed as follows: the opening degree of the flow regulating valve 110 is regulated until the hot water temperature of the outlet water reaches the set hot water temperature.

In the thermal equilibrium state, the temperature of the hot water becomes 40 ℃, which is the set hot water temperature, while a heat amount higher than the required heat amount is supplied from the

heaters

11, 12, 13, and therefore, if the opening degree of the flow rate adjustment valve 110 is continuously maintained, the temperature of the hot water discharged becomes a temperature higher than the set hot water temperature, thereby causing dissatisfaction of the user with respect to the hot water temperature.

In the prior art, if the temperature of the hot water reaches the set hot water temperature, namely 40 ℃, the

heaters

11, 12 and 13 are turned Off (Off), but the durability is reduced due to frequent On/Off (Off).

Therefore, in the present invention, the configuration is: the opening degree of the flow rate adjustment valve 110 is reduced in a state where the supply heat amount is fixed while maintaining the open (On) state of the

heaters

11, 12, 13, thereby gradually reducing the circulation flow rate of the supply water circulating through the second heat exchanger 40. If the circulation flow rate of the supply water is adjusted as described above, the heat ratio can be controlled even without turning On (On)/Off (Off) the

heaters

11, 12, 13.

In step S206, the control unit determines whether there is a change in the temperature of the supply water measured by the supply water temperature sensor 120.

According to the judgment result, if there is a supply water temperature change, step S207 is performed, otherwise, the opening degree adjustment of the flow rate adjustment valve 110 and the supply water temperature measurement process of steps S205 and S206 are continued.

In step S207, if the supply water temperature measured by the supply water temperature sensor 120 is lower than the first heater temperature, step S208 is performed, otherwise step S209 is performed.

In step S205, if the opening degree of the flow rate adjustment valve 110 is decreased to decrease the circulation flow rate, the deviation between the temperature of the feed water flowing into the second heat exchanger 40 and the temperature of the return water after passing through the second heat exchanger 40 becomes large, and therefore the feed water temperature rises. In general, if the temperature of the supplied water exceeds 80 degrees (first heater temperature), burning due to high temperature may occur and heat resistance of parts may be problematic, and therefore, it is preferable to turn Off (Off) the

heaters

11, 12, 13.

In step S208, before the feed water temperature reaches the first heater temperature, the flow rate and the circulation flow rate passing through the flow rate adjustment valve 110 are calculated by the following equation 2 in order to perform Feedback (Feedback) control of the opening degree of the flow rate adjustment valve 110.

[ mathematical formula 2]

Target circulation flow is required heat/(water supply temperature-return water temperature)/60

In the above example, in the case where the required heat amount is 18,000kcal/h, the supply water temperature is 80 ℃, and the return water temperature is 40 ℃, if these are calculated by substituting into equation 2, the circulation flow rate is 7.5 Lpm.

If the circulation flow rate is calculated by the above-described procedure, the opening amount of the flow rate adjustment valve 110 is adjusted in accordance with the circulation flow rate calculated by performing step S205.

In step S209, if the supply water temperature exceeds the first heater temperature, the

heaters

11, 12, and 13 are turned Off (Off) in order to prevent the durability of the components from being lowered due to the high temperature. For example, the first heater temperature may be set to 80 ℃.

In step S210, if the supply water temperature decreases below the second heater temperature, step S211 is performed, otherwise the Off (Off) state of the heater is maintained. In the above example, it may be configured such that if the supply water temperature reaches 75 ℃, the (On)

heaters

11, 12, 13 are turned On.

If the

heaters

11, 12, 13 are turned On (On), the feed water temperature rises, and an opening degree adjustment process of the flow rate adjustment valve 110 based On Feedback (Feedback) control is performed according to a change in the feed water temperature in step S205.

Through the above-described process, the heat rate of the hot water required by the user can be controlled only by adjusting the opening degree of the flow rate adjustment valve 110 without turning Off the (Off)

heaters

11, 12, and 13.

According to the boiler and the control method described above, it is possible to respond to a temperature change of the supplied water in time only by adjusting the opening degree of the flow rate adjustment valve 110, so that it is possible to reduce a deviation of the hot water temperature. In addition, since the electric boiler can supply the temperature of the hot water required by the user by adjusting only the opening degree of the flow rate adjustment valve 110 without turning Off (Off) the

heaters

11, 12, and 13, it is possible to prevent the life of the relay required to supply the electric power to the

heaters

11, 12, and 13 from being shortened, and to reduce the maintenance cost. Also, in the case where the temperature of the supply water supplied to the second heat exchanger 40 is rapidly changed, such as when switching to the hot water mode during heating operation, the amount of supply heat can be rapidly reduced only by adjusting the opening degree of the flow rate adjustment valve 110, and thus scalding of the hot water user can be prevented. Further, the user can reduce the energy supplied from the first heat exchanger 10 by flowing only the flow rate required for the set hot water temperature.

The present invention is not limited to the above-described embodiments, and those having basic knowledge in the technical field to which the present invention pertains can understand that various modifications and variations can be made without departing from the technical spirit of the present invention.

Claims

1. A heating and water heating boiler, comprising:

a first heat exchanger (10) that generates heated supply water and includes a plurality of heaters (11, 12, 13) that generate heat with a fixed amount of heat in accordance with power supply;

a second heat exchanger (40) generating hot water by heat exchange between the supply water supplied from the first heat exchanger (10) and the straight supply water;

a flow rate adjustment valve (110) for adjusting a circulation flow rate of the supply water circulated through the second heat exchanger (40) in a hot water mode;

and a control unit that calculates a required amount of heat corresponding to a set hot water temperature of a user in a hot water mode, sets the number of heaters (11, 12, 13) to be opened so that the amount of supply heat supplied from the first heat exchanger (10) is higher than the required amount of heat, and reduces the opening degree of the flow rate adjustment valve (110) so as to reduce the circulation flow rate to correspond to the required amount of heat.

2. The heating and water heating boiler according to claim 1,

a supply water temperature sensor (120) for measuring the temperature of the supply water flowing into the second heat exchanger (40),

and a return water temperature sensor (130) for measuring the temperature of the return water passing through the second heat exchanger (40),

and the control part calculates the circulation flow rate according to the temperature difference measured from the supply water temperature sensor (120) and the return water temperature sensor (130) and the required heat amount.

3. The heating and water heating boiler according to claim 1,

the flow rate control valve (110) is provided in a hot water side return pipe (89) connected to an outlet side of the second heat exchanger (40).

4. A method of controlling a heating and water-heating boiler, the heating and water-heating boiler comprising: a first heat exchanger (10) generating heated supply water; a second heat exchanger (40) generating hot water by heat exchange between the supply water supplied from the first heat exchanger (10) and the straight supply water; a control part for controlling the amount of heat supplied from the first heat exchanger (10) according to the amount of heat required according to the set hot water temperature of the user in a hot water mode, the control method comprising the steps of:

a) sensing a flow rate of the direct supply water, thereby sensing a hot water usage of a user;

b) calculating a required quantity of heat corresponding to a set hot water temperature set by a user, and setting the number of heaters (11, 12, 13) to be turned on so that the supply quantity of heat is higher than the required quantity of heat at the control part;

c) generating supply water by supplying the set supply heat and circulating the supply water to the first heat exchanger (10) through the second heat exchanger (40);

d) reducing the opening degree of a flow rate adjustment valve (110) in such a manner that the circulation flow rate of the supply water passing through the second heat exchanger (40) corresponds to the required heat amount.

5. The method of controlling a heating and water heating boiler according to claim 4,

after the step d), the temperature of the supply water flowing into the second heat exchanger (40) is measured by a supply water temperature sensor (120), and the heaters (11, 12, 13) are turned off in the case where the measured temperature of the supply water exceeds the temperature set in the control part.

6. The method of controlling a heating and water heating boiler according to claim 4,

the temperature of the supply water flowing into the second heat exchanger (40) is measured by a supply water temperature sensor (120),

in the step d), if the measured temperature of the supplied water varies to exceed a set range, the opening degree of the flow rate adjustment valve (110) is adjusted.

7. The method of controlling a heating and water heating boiler according to claim 4,

in the step d), a supply water temperature of supply water flowing into the second heat exchanger (40) and a return water temperature of return water passing through the second heat exchanger (40) are measured,

the control part calculates the circulation flow rate according to the difference between the supply water temperature and the return water temperature and the required heat amount, and adjusts the opening degree of the flow rate adjustment valve (110) to correspond to the calculated circulation flow rate.