JPH08178422A - Hot water supplying apparatus - Google Patents

Abstract

PURPOSE: To provide a hot water supplying device which enables preventing of dew formation of a heat exchanger when a combustion value of a burner is low. CONSTITUTION: In a hot water heater 30 which is made up of a burner 20 and a heat exchanger 30 to transmit heat to water supplied, the heat exchanger 30 is connected to a supply pipe 60 on the side of the initial end thereof. With a vertical multi-stage structure of the heat exchanger 30 inside, a water pipe 32 is connected to a hot water pipe on the side of the final end thereof being returned at least at one point, a bypass pipe 36 is extended outside the heat exchanger 30 being branched off a return part of the water pipe 32 of the heat exchanger 30 to be connected to the hot water pipe and a control valve 37 is provided to change a flow rate to the bypass pipe 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a burner and a heat exchanger for transferring heat from the burner to the feed water, and the burner amount of the burner is adjusted according to the required hot water temperature and hot water amount. Concerning the hot and cold water heater.

[0002]

2. Description of the Related Art Heretofore, in this type of water heater, the burner has a burning capacity generally about three times from the maximum to the minimum, and the heat exchanger is designed to meet the maximum capacity.

[0003]

However, in such a conventional technique, the heat transfer area of the heat exchanger becomes excessive under use conditions where the burner burns a small amount, and the fin plate near the water tube surface and the water tube of the heat exchanger is increased. Etc. temperature will be very low.

When the temperature of the surface of the water pipe of the heat exchanger falls below the dew point in the environment of pressure and humidity of the combustion gas, the water vapor in the combustion gas condenses and condenses on the heat exchanger, and the dew water itself becomes heat. There is a problem that corrosion of the exchange is caused and durability is reduced.

The fuel gas sometimes contains a trace amount of sulfur as an impurity, and a sulfur compound is added as an odorant. When these sulfur are dissolved in dew condensation water, a corrosive property is promoted by a chemical phenomenon. Therefore, it is desirable to prevent condensation on the heat exchanger as much as possible.

The present invention has been made by paying attention to such a conventional problem, and even when the burner has a low combustion amount,
It is an object of the present invention to provide a water heater in which condensation of the heat exchanger does not easily occur.

[0007]

The gist of the present invention for solving the above problems resides in the following items.

In a water heater comprising a burner (20) and a heat exchanger (30) that transfers heat from the burner (20) to water supply, the heat exchanger (30) is heated from the middle of a water pipe (32). A water heater comprising a bypass pipe (36) branching out of the exchange (30) and a control valve (37) for changing a flow rate to the bypass pipe (36).

In a water heater comprising a burner (20) and a heat exchanger (30) for transferring heat from the burner (20) to the water supply, the heat exchanger (30) has a water supply pipe (60) at the starting end side. It has a water pipe (32) that is connected and has an upper and lower multi-stage structure inside and folds back at least at one place, and the terminal side has a water pipe (32) connected to the hot water supply pipe (35). Branch to the heat exchanger (3
0) A water heater comprising a bypass pipe (36) extending to the outside and connected to the hot water pipe (35), and a control valve (37) for changing a flow rate to the bypass pipe (36).

3. The water heater according to Item 1 or 2, wherein the control valve (37) switches the flow rate in conjunction with the combustion amount of the burner (20).

[0011]

[Function] When the hot water supply temperature of the water heater is set and the hot water tap is opened, the amount of hot water according to the opening of the hot water tap flows out, and the same amount of water flows into the water pipe (32) of the heat exchanger (30). To do. The combustion amount of the burner (20) is controlled so that the difference between the set temperature and the feed water temperature is multiplied by the amount of water and correction is made as necessary to obtain the required amount of heat.

When the temperature is set low, the burner (20)
The combustion amount of is also controlled to a small amount, but the flow rate of the bypass pipe (36) of the heat exchanger (30) is increased in conjunction with the control for keeping the combustion amount below a certain amount, or in accordance with the set temperature,
The water pipe (32) in the heat exchanger (30) activates the control valve (37) to reduce or close.

The feed water is heated by a part of the water pipe (32) of the heat exchanger (30) to sufficiently absorb the heat to raise the temperature, and depending on the bypass pipe (36) and the control condition, a water pipe (after the branching part). 32) and is supplied to the hot water supply pipe (35). Therefore, the load on the heat exchanger (30) is reduced, the amount of heat heated by the burner (20) exceeds the amount of heat cooled by the feed water, the heat exchanger (30) is maintained at a high temperature, and dew condensation is prevented. .

Unless condensation occurs, steam or sulfur oxide SO
When x is a gas as it is, it hardly corrodes the heat exchanger (30) and can also prevent the combustion of the burner (20) from being hindered.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The water heater 10 has a casing 11 in which a burner 20 and a heat exchanger 30 are housed. A box-shaped combustion chamber 22 is formed substantially in the center of the casing 11, the burner 20 is disposed below the interior of the combustion chamber 22, and a combustion fan 21 that sends combustion air is provided under the burner 20. An exhaust unit 40 is disposed above the combustion chamber 22 via a duct 23 that is open at the bottom.

The burner 20 has a large number of nozzles 24, and while the fuel gas is blown out from the nozzles 24, the combustion fan 21
The air sent by is blown out from the space around the burner 20 and mixed with the fuel gas to burn. In the burner 20, the gas supply pipe 50 has a gas solenoid valve 5
1, the gas proportional valve 52, and the gas capacity switching valve 53 are connected.

The suction port of the combustion fan 21 is open inside the casing 11 to prevent noise from leaking to the outside. An air intake port 12 is opened at a side portion of the casing 11 to supply fresh air to the combustion fan 21. An air filter 13 is provided at the air inlet 12.
Is interposed.

The heat exchanger 30 is arranged above the combustion chamber 22, and has a structure in which a water pipe 32 penetrates a large number of thin plates called fin blocks 31 arranged in parallel. The fin block 31 is a material having a high heat transfer effect and is usually made of metal. The fins of the fin block 31 are arranged parallel to the flow of the combustion gas so that the heat is exchanged while the combustion gas passes between the fins. Has been done.

The water pipe 32 of the heat exchanger 30 has a starting end side 32a.
Is connected to the water supply pipe 60, and the upper stage pipe 33a and the lower stage pipe 3 are internally connected.
3b has an upper and lower multi-stage structure and is folded back at at least one bent portion 34, and the terminal end side 32b is connected to the hot water supply pipe 35. The water pipe 60 has a temperature sensor 61 and a water amount sensor 6
2 are provided.

A bypass pipe 36 is provided which branches from the bent portion 34 of the water pipe 32 and extends to connect to and merge with the hot water supply pipe 35 after the terminal end 32b of the water pipe 32. A control valve 37 is provided at the confluence of the hot water supply pipe 35 and the bypass pipe 36. The control valve 37 operates so that when one opening on the inflow side is opened, the other opening on the inflow side is closed on the contrary. The end of the hot water supply pipe 35 extends to a place for receiving hot water, and hot water taps 39, 39 ... Are provided there.

Exhaust chamber 40 connected to the top of combustion chamber 22
The exhaust pipe 41 is electrically connected to the outside of the casing 11, and a CO sensor 42 for monitoring the CO concentration in the exhaust gas is provided in a part of the exhaust pipe 41. Although not shown, an operation mechanism for controlling each device, a sensor, a calculation mechanism, and the like are provided.

Next, the operation will be described. When the hot water supply temperature of the water heater 10 is set and the hot water tap 39 is opened, the amount of hot water according to the opening degree of the hot water tap 39 flows out, and the same amount of water flows from the water supply pipe 60 into the water pipe 32 of the heat exchanger 30. . The combustion amount of the burner 20 is controlled to a required heat amount obtained by multiplying the difference between the set temperature and the feed water temperature by the water amount.

The gas solenoid valve 51 is normally kept in a closed state when the power is off, and is kept in an open state when the power is turned on and the electromagnet included therein is excited by energization. When the fuse is blown and the exciting current is cut when the air is cooked or overheated, it returns to the closed position and shuts off the fuel gas. When the power is cut off due to a power outage, the gas is also shut off to avoid danger. Further, the exciting current is cut off by a signal of a sensor that detects when the flame is extinguished during combustion.

The gas proportional valve 52 controls the amount of fuel gas supplied to the burner 20 according to the output signal of the calculation mechanism.
The calculation mechanism calculates the required heat quantity by multiplying the difference between the set hot water temperature and the water supply temperature by the water quantity, corrects it if necessary, and converts it into a signal for output. The set hot water temperature is measured by the user, the feed water temperature is measured by the temperature sensor 61, and the water amount is measured by the water amount sensor 62 and input to the calculation mechanism.

The gas capacity switching valve 53 opens when the output signal of the fuel gas amount control of the arithmetic mechanism is insufficient due to the capacity of the main burner, and supplies gas to an auxiliary burner (not shown).

Since a large amount of CO is generated during abnormal combustion such as lack of air, it can be known that abnormal combustion occurs when the CO concentration becomes high. Therefore, a signal from the CO sensor 42 is received to avoid abnormal combustion. It is possible to safely control the fuel consumption by reducing the fuel, or by shutting off the exciting current to the gas solenoid valve 51 as described above.

For example, when the temperature is set low, the burner 2
The combustion amount of 0 is also controlled to a small amount, but the combustion amount is 20
When the amount becomes less than a certain amount such that dew condensation occurs on the bypass pipe 36, the bypass pipe 36 is interlocked with the control of the burner 20.
The control valve 37 provided in the confluence part connected to 5 controls the operation so that the flow path on the side of the bypass pipe 36 is opened and the upper pipe 33a of the water pipe 32 is throttled or closed. As a result, the feed water is mainly heated by the lower pipe 33b which is a part of the water pipe 32 of the heat exchanger 30, and the flow rate of the portion of the burner 20 in contact with the flame is reduced. And passes through the bypass pipe 36 and is supplied to the hot water supply pipe 35.

That is, the amount of flowing water is limited to 0 or a very small amount on the starting end side 32a of the water pipe 32 of the heat exchanger 30 behind the branch connected to the bent portion 34. Therefore, the load on the heat exchanger 30 is reduced, the amount of heat heated by the burner 20 exceeds the amount of heat cooled by the feed water, the heat exchanger 30 is maintained at a high temperature, and dew condensation is prevented.

If no condensation occurs, steam or sulfur oxide SO
Since x remains a gas, it hardly corrodes the heat exchanger 30, and water droplets do not drop to hinder the combustion of the burner 20.

Further, since the hot water temperature is adjusted by shortening the distance that the water passes through the water pipe 32 of the heat exchanger 30, that is, the heating time, it is possible to obtain a slightly hot water of a required temperature and amount without adding cold water.

By eliminating the corrosion, the durability of the heat exchanger 30 is improved, the range of choice is expanded to materials that are not corrosion resistant, and the manufacturing cost is reduced.

Although the bypass pipe 36 is branched from the bent portion 34 in the above embodiment, the bent portion 34 is
However, the water pipe 32 may be an intermediate portion. Although the bypass pipe 36 is branched from only one place, it may be provided at a plurality of places.

Further, the control valve 37 in the above embodiment is
The flow rate of the water pipe 32 of the heat exchanger 30 of the heat exchanger 30 and the flow rate of the external bypass pipe 36 are controlled in reverse interlocking, but the flow rate may be switched stepwise or continuously, and the valve closed position is all. It may be closed or a minute flow rate may be left. Alternatively, a minute flow rate bypass may be provided. Also, without providing in the connection part,
It is also possible to adjust or switch only the flow rate of the bypass pipe 36. In this case, if the flow rate of the bypass pipe 36 increases, the flow rate of the starting end side 32a decreases, thereby achieving the purpose of control. Therefore, the mounting position of the control valve may be anywhere in the middle portion of the bypass pipe 36. Water is supplied by heat exchanger 3
Control valve 37 to either the water pipe 32 of 0 or the bypass pipe 36.
It is divided into proportions according to the opening degree of.

When the combustion amount is controlled by changing the fuel amount supplied to the burner 20, the control valve 37 responds to the fuel amount.
Although the opening of the heat exchanger 30 is changed, the opening may be changed according to the set temperature without being related to the control of the burner 20. The flow rate of the bypass pipe 36 may be increased in a certain temperature range.

When an auxiliary burner (not shown) is provided which is operated when the capacity of the main burner of the burner 20 is insufficient,
Fuel gas and air are suitable for combustion when they are in a certain mixing ratio range, but the amount of gas blowing from the nozzle 24 must be within a certain range in order for the gas blowing from the nozzle to mix with air at an appropriate mixing ratio. . Therefore, in order to increase the gas amount and increase the combustion amount, it may be necessary to increase the number of nozzles and the distribution area of the nozzles.

That is, even if the gas amount is reduced in order to reduce the combustion amount, it deviates from the proper mixing ratio. If the combustion amount is increased / decreased by increasing / decreasing the gas amount, the maximum and minimum are practically 3: The limit is about 1. Therefore, it is necessary to increase or decrease the number of nozzles in a combustion device with large load fluctuations. Generally, it is possible to provide a plurality of burners having nozzles and increase or decrease the number of burners that supply gas according to the load. it can.

[0037]

According to the water heater according to the present invention, the heat exchanger can maintain an appropriate high temperature even when the load is low and the amount of heat is small with respect to the amount of water to be heated, so that dew condensation can occur. Absent. Therefore, there is no fear of corrosion due to dew condensation, durability can be improved and a good condition can be maintained for a long period of time, and the selection range of constituent materials of the heat exchanger can be expanded to reduce manufacturing cost. Therefore, it is possible to provide an inexpensive and long-life water heater.

[Brief description of drawings]

FIG. 1 is a schematic view showing a water heater according to an embodiment of the present invention.

[Explanation of symbols]

 10 ... Water heater 11 ... Casing 12 ... Air intake port 13 ... Air filter 20 ... Burner 21 ... Combustion fan 22 ... Combustion chamber 23 ... Duct 24 ... Nozzle 30 ... Heat exchanger 31 ... Fin block 32 ... Water pipe 35 ... Hot water supply pipe 36 ... Bypass pipe 37 ... Control valve 39 ... Hot water tap 40 ... Exhaust chamber 41 ... Exhaust pipe 42 ... CO sensor 50 ... Gas supply pipe 51 ... Gas solenoid valve 52 ... Gas proportional valve 60 ... Water supply pipe 61 ... Temperature sensor 62 ... Water amount sensor

Claims (3)

[Claims] 1. A water heater comprising a burner and a heat exchanger for transferring heat from the burner to feed water, comprising: a bypass pipe branching from the middle of a water pipe of the heat exchanger to the outside of the heat exchanger; A water heater provided with a control valve for changing a flow rate to a pipe. 2. A water heater comprising a burner and a heat exchanger for transferring heat from the burner to water supply, wherein the heat exchanger has a start end side connected to a water supply pipe and has a vertical multistage structure at least. A bypass pipe that is folded back at one location and has a water pipe whose end side is connected to the hot water supply pipe, extends from the folded portion of the water pipe of the heat exchanger and extends outside the heat exchanger, and is connected to the hot water supply pipe; Water heater having a control valve for changing the flow rate to the water heater. 3. The water heater according to claim 1, wherein the control valve switches the flow rate in association with the combustion amount of the burner.