JPH0341738B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Application and Summary of the Invention) The present invention relates to a water heater, and the present invention relates to a water heater. This prevents the occurrence of drainage and improves the setting sensitivity of the tap water temperature.

(Prior art and its problems) In a conventional water heater, a configuration as shown in FIG. By adopting a combination of the above two, hot water at a desired temperature can be drawn from a faucet installed below the junction of these two circuits.

In the case of this conventional method, the amount of water passing through the heated tube 11 of the heated circuit 1 is smaller than when the entire amount of water from the inlet is heated by a heat exchanger, so the amount of water passing through the heated tube 11 of the heated circuit 1 is The temperature of the pipe 11 increases, making it difficult for drainage to occur.

However, in the case of a type in which the adjustment range of the amount of hot water discharged is wide and the temperature of hot water discharged is also wide, drainage may occur in the heated tube if the conventional type is simply adopted as is.

This is because in a water heater with a large hot water supply capacity, the total length of the heated pipe 11 becomes long, and the temperature of the heated pipe at the downstream side of the combustion exhaust becomes low. In particular, when a large amount of low-temperature hot water is to be obtained, this tendency becomes remarkable, and the atmospheric gas in the heated tube 11 condenses and drips into the heat exchanger.

As a solution to this problem, Japanese Unexamined Patent Application Publication No. 1986-
Disclosed in Publication No. 205043 and JP-A-60-259855
In this publication, a gas proportional valve is inserted into the circuit to the gas burner that heats the tube to be heated, and the temperature at the outlet of the heat exchanger is controlled to be maintained at a constant high temperature. However, cold water in a bypass circuit that bypasses the heat exchanger is mixed with the hot water at a constant temperature using a mixing device using a motor to obtain hot water at a desired temperature.

However, in all of this prior art,
The temperature of hot water taken out from the water heater (hot water temperature)
Since the mixing device attempts to maintain the set temperature, if the total amount of water flowing through the water heater is constant when the faucet opening is constant, when the set temperature is changed, There is a problem in that it takes a relatively long time for the hot water temperature to reach the set temperature.

In a water heater, the temperature of hot water discharged is determined by the amount of hot water discharged, the combustion amount of the gas burner, and the heat exchange efficiency of the heat exchanger. However, in this prior art, the temperature of the hot water from the heated pipe is maintained at a constant temperature and the mixing ratio of cold water to it is changed, so if the set temperature is changed, The following operations will continue to maintain the outlet hot water temperature at the new set temperature.

First, the mixing device sets the mixing ratio of cold water and hot water corresponding to the new set temperature.

Next, since the total amount of water passing through the water heater is constant, changing the mixing ratio will change the amount of water passing through the heated pipes, and the temperature of the hot water from the heated pipes will be maintained constant. Therefore, set a new combustion amount for the gas burner.

As a result, the flow rate of the hot water changes, and the mixing device performs an operation to set a new mixing ratio in accordance with the new set temperature.

By repeating the above operations, the hot water temperature is maintained at the set temperature.

In this way, when the set temperature is changed, it takes a relatively long time to reach equilibrium with the new set temperature.

(Technical Problem) The present invention has a heat exchanger that includes a heated circuit 1 that includes a heated pipe 11 and a bypass circuit 2 that bypasses the heated pipe 11, and In a water heater that maintains the temperature at the set temperature set by the hot water temperature setting device, this method prevents the occurrence of drainage in the heat exchanger and the time required for the outlet temperature to reach the set temperature. The challenge is to shorten the time.

(Technical Means) The technical means of the present invention taken to solve the above-mentioned problems is to provide a hot water temperature detection means for detecting the hot water temperature downstream of the confluence of the heated circuit 1 and the bypass circuit 2. The output from the hot water temperature detection means operates a proportional control valve for gas inserted in the circuit to the gas burner 15 to maintain the hot water temperature at a set temperature, and the heated circuit 1 and the bypass are connected to each other. A flow ratio adjustment valve 3 is inserted into one or both of the circuits between the confluence with the circuit 2 and the branch point, and a detection means 4 is provided at a specific location of the heated circuit 1 to detect the temperature of this section. is provided, and the output of this detection means 4 is connected to the flow rate coverage adjustment valve 3.
The flow rate ratio adjustment valve controls the flow rate ratio between the heated circuit 1 and the bypass circuit 2 in accordance with the output from the detection means 4 to maintain the heated pipe 11 at a temperature at which condensation does not occur. ``I decided to do it.''

(Operation) The above technical means of the present invention operates as follows.

When the hot water temperature on the downstream side of the confluence of the heated circuit 1 and the bypass circuit 2 is maintained at a specific set temperature,
Even if the flow rate ratio between the heated circuit 1 and the bypass circuit 2 changes, the amount of combustion gas remains at a constant value corresponding to the set temperature as long as the total flow rate does not change. Therefore, the proportional control valve for gas is operated in accordance with the output from the outlet hot water temperature detection means, and the amount of gas supplied to the gas burner 15 becomes a predetermined value corresponding to the set temperature.

Under this condition, the ratio between the flow rate of the heated circuit 1 and the flow rate of the bypass circuit 2 is adjusted by the flow ratio adjustment valve 3 and the detection means 4,
The temperature on the first side is maintained at a predetermined temperature that does not cause drainage. That is, when the heated tube 11 side shifts to the low temperature side due to a change in the combustion amount of the gas burner 15, the flow rate of the heated tube 11 side is reduced compared to the flow rate of the other bypass circuit 2. As a result, the amount of heating per unit flow rate of the water to be heated on the side of the heated tube 11 increases, moves to the high temperature side, and is maintained at the predetermined temperature.

(Effects) Since the present invention has the above configuration, it has the following unique effects.

No matter what temperature the hot water temperature is set to,
Since the surface temperature of the heated tube 11 is maintained at a temperature at which no condensate is generated, the inconvenience caused by the condensate is eliminated.

Furthermore, since the hot water temperature is set by the operation of the proportional control valve for gas inserted in the gas circuit to the gas burner 15 based on the output from the hot water temperature detection means, it is different from the prior art described above. In this way, the time required for the tap water temperature to reach the set temperature can be shortened. In other words, the setting sensitivity of the tapping temperature is improved compared to the prior art.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 2 and 3.

In the first embodiment shown in FIGS. 2 and 3, in order to enable large-capacity heat exchange, as shown in FIG.
The heated tube group 13, 14 consisting of 11 is made into two stages,
A gas burner 15 is employed as a heating source. Therefore, the heated tube groups 13 and 14 are arranged in upper and lower stages in the can body 10 and are interconnected to form a lower combustion chamber 16 of the lower heated tube group 14.
In order to increase the combustion capacity in this combustion chamber,
A fan 17 is used to feed combustion air.

Further, a bypass circuit 2 is provided outside the can body 10, and both ends of the heated tube groups 13 and 14 are communicated with each other. Therefore, part of the water flowing through the water circuit is
It flows from branch point 21 to confluence point 22 without passing through a heat exchanger.

Next, the first thermistor 41 that detects the water temperature or the tube wall temperature is adopted as the above-mentioned detection means 4,
This first thermistor 41 is provided downstream of the heated circuit 1 consisting of the heated pipes 11, 11, and the first proportional control valve 3 as the flow ratio adjustment valve 3.
1 is inserted into the heated circuit 1 near the junction 22.

The first proportional control valve 31 has a known configuration.
The opening degree of the valve is changed by the first drive circuit 51 which compares the voltage applied to the thermistor 41 with the constant voltage and outputs an output according to the difference. Therefore, if there is no difference between the set temperature corresponding to the set voltage and the detected temperature corresponding to the voltage detected by the first thermistor 41, the current valve opening degree is maintained and the detection is performed. When the temperature is low, an output signal in the direction of reducing the valve opening is applied from the first drive circuit 51 to the first proportional control valve 31. Conversely, when the detected temperature becomes high, the operation opposite to the above is performed.

As a result, the temperature of the heated circuit 1 can be maintained even if the combustion amount of the gas burner 15 and the flow rate of the water circuit change.
The temperature of the combusted tube 11 is always maintained at a constant temperature.

In this embodiment, since the outlet side temperature of the heated tube group 14 on the lower downstream side is detected, the temperature of this part is set to a constant temperature within the range of 75°C to 90°C (hot water temperature). be. When the detection point in the heated circuit 1 is located on the upstream side compared to the above embodiment (for example, when detecting the water temperature in the middle part of the heated tube 11), the set temperature may be lowered accordingly. Set.

Next, in this embodiment, a second thermistor 61 for separately detecting the outlet temperature is provided on the downstream side of the confluence point 22, and a second proportional control valve 62 is further inserted into the gas circuit 7 to the gas burner 15. There is.

This second proportional control valve 62 is connected to a second drive circuit 63.
The valve opening degree changes depending on the output from the gas burner, and the combustion amount of the gas burner is changed. The second drive circuit 63 makes a comparison and applies an output corresponding to the difference to the second proportional control valve 62.

Therefore, the output of the second proportional control valve 62 maintains the outlet hot water temperature at the set temperature regardless of changes in the amount of hot water.

As described above, the combination of two proportional control valves allows the temperature and amount of hot water to be varied over a wide range, and prevents condensate from forming and dripping in the heated pipe within this adjustment range.

In the first embodiment described above, the first proportional control valve 31 is used as the flow rate ratio adjusting valve 3, and this is provided at the downstream end of the heated circuit 1. However, the insertion position of the proportional control valve 31 is as follows. It may be set at any position in the circuit to be heated 1, or conversely, it may be provided in the bypass circuit 2. In the latter case, the operation of the proportional control valve may be set opposite to that in the first embodiment.

In the case of the first embodiment and the above-mentioned modification, by adjusting the flow rate of either the heated circuit 1 or the bypass circuit 2, the flow rate ratio of both circuits is changed, but the flow rate ratio is directly changed. It is also possible to do so.

As this method, for example, a configuration in which a flow ratio adjusting valve 3 as shown in FIG. 4 is inserted into the confluence point 22 or the branch point 21 can be adopted.

In this case, the valve body 32 is moved by the output mechanism 33, and the ratio between the flow rate on the bypass circuit 2 side and the flow rate on the heated circuit 1 side changes directly. In this case as well, similarly to the proportional control valve described above, an output corresponding to the difference between the detected temperature and the set temperature is input from the drive circuit to the output mechanism.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is an explanatory diagram of the first embodiment, Fig. 3 is a plan view of a group of heated tubes, and Fig. 4 is an explanatory diagram of the main parts of the second embodiment. FIG. 5 is an explanatory diagram of a conventional example, and in the figure, 1... Heated circuit, 10... Can body, 11... Heated tube, 2... Bypass circuit, 3... Flow rate ratio adjustment valve, 4... ...Detection means.

Claims (1)

[Claims] 1 has a heat exchanger comprising a heated circuit 1 having a heated pipe 11 and a bypass circuit 2 that bypasses the heated pipe 11, and controls the temperature of hot water discharged from the water heater by a hot water temperature setting device. In a water heater configured to maintain a preset temperature, a hot water temperature detection means for detecting the hot water temperature downstream of the confluence of the heated circuit 1 and the bypass circuit 2 is provided, and the hot water temperature detected by the hot water temperature detection means is The outlet temperature is maintained at a set temperature by operating a proportional control valve for gas inserted into the circuit to the gas burner 15 according to the output, and the temperature is maintained at a set temperature from the confluence point to the branch point of the heated circuit 1 and the bypass circuit 2. A flow ratio adjustment valve 3 is inserted into one or both of the circuits between 1 and 2, and a detection means 4 is provided at a specific location of the heated circuit 1 to detect the temperature of this portion. is input to the flow rate ratio adjustment valve 3, and this flow rate ratio adjustment valve connects the heated circuit 1 and the bypass in order to maintain the heated pipe 11 at a temperature that does not cause condensation according to the output from the detection means 4. A water heater that controls the flow rate ratio with circuit 2.