JPH07107462B2 - Water heater with bypass channel - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater which eliminates post-boiling that occurs when the water heater is used again after being temporarily suspended.

2. Description of the Related Art A conventional water heater of this type has a water inlet pipe as shown in FIG.
A bypass water passage 23 is connected in parallel with the hot water supply heat exchanger 22 via 21, a motor-driven water amount proportional valve 24 is connected to the connection point, and then a thermistor 25 is connected to communicate with the hot water outlet pipe 26.
Due to the superior structure, city water passes through the water inlet pipe 21 and the branch point 27.
The water in the hot water supply heat exchanger 22 is heated by the burner 28, merges with the motor-driven water amount proportional valve 24, and is supplied from the hot water supply pipe 26 by the hot water supply heat exchanger 22 and the bypass water passage 23. To be done. The bypass flow rate is a motor driven water proportional valve.
When the hot water flow rate is too high and exceeds the maximum capacity of the water heater and the hot water temperature falls below the set temperature, the hot water flow rate can be reduced by the motor-driven water volume proportional valve 24 to guarantee the hot water temperature at the set temperature. Therefore, no measures were taken against the post-boiling that occurs when the hot water is re-opened after the hot water is temporarily suspended. (For example, Japanese Patent Application Laid-Open No. 58-205043) Problems to be Solved by the Invention However, with the above-described configuration and control, there is a problem that after-boiling cannot be eliminated and the cost is high.

The present invention solves such a conventional problem, and an object thereof is to eliminate post-boiling at low cost.

Means for Solving the Problems In order to solve the above problems, the water heater with a bypass water passage of the present invention is provided with an electromagnetic valve in the bypass water passage provided in parallel with the heat exchanger water passage for hot water supply, and after temporarily suspending the use of the water heater. When the water is reused, the post-boiling amount of the heat exchanger for hot water supply is calculated from the combustion amount before hot water supply interruption and the hot water supply interruption time.If the post-boiling amount is a certain amount or more, the solenoid valve of the bypass channel when reusing hot water Is to be opened only for a certain period of time.

Effect The present invention can eliminate post-boiling at the time of re-melting hot water at a low cost by controlling the above by using the solenoid valve in the bypass water channel.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a water inlet, which branches a water passage at a branch point 2, and one of the water inlets passes through a hot water supply heat exchanger 3 and communicates with a confluence point 4. The other communicates with the confluence 4 via the solenoid valve 5. There is a thermistor 6 for measuring the mixing temperature through the confluence point 4 and communicates with the hot water outlet 7. The fuel proportional valve 8 controls the combustion amount of the burner 9.

In the above configuration, the sequence of opening and closing the solenoid valve 5 when the water heater is reused after being temporarily suspended is
Shown in the figure. In the sequence, when the use of the water heater is temporarily suspended and the water heater is reused, the magnitude of the post-boiling amount is calculated from the combustion amount A immediately before the hot water supply is stopped and the hot water supply stop time t, and is expressed by the post-boiling index η. When the boiling index is 0.5 or more, it is judged that the post-boiling of water in the heat exchanger is remarkable, and the solenoid valve 5 in the bypass water channel is kept open for a certain time C, and the high-temperature water and the bypass due to post-boiling in the heat exchanger are bypassed. When the water in the water channel is mixed and cooled, and hot water is discharged, when η is less than 0.5, it is determined that there is little post-boiling of water in the heat exchanger, and after closing the solenoid valve 5 in the bypass water channel, hot water is discharged. It is a thing. still,
The fixed time C is the time until the high-temperature water due to post-boiling in the heat exchanger 3 completes passing through the confluence point 4.

Next, the post-boiling index η will be described. The amount of after-boiling is the amount of heat of the fins / drums of the high-temperature heat exchanger immediately after combustion is stopped, and when the hot water supply is stopped, heat is transferred to the stopped water in the water tubes of the heat exchanger by the heat capacity of the fins / drums of the heat exchanger. Is.

If the time required to transfer heat from the fins / drums of the high-temperature heat exchanger to the water in the heat exchanger water pipe immediately after the combustion is stopped is the saturated heat storage time T of the water in the heat exchanger, the amount of after-boiling will be after the hot water supply is stopped. It reaches a maximum at T time, and thereafter, the high temperature water in the heat exchanger radiates heat to the atmosphere via the fins and drums and decreases. Therefore, assuming that the hot water supply stop time is t, t / T indicates a temporal post-boiling state. Further, by using the value A / I obtained by dividing the value indicating the absolute amount of the post-boiling amount by the maximum combustion amount I of the combustion amount A immediately before the hot water supply is stopped, the post-boiling index η is t / T of 1 or less. when When t / T is greater than 1, By expressing, the level of the post-boiling amount can be represented by η.

Effects of the Invention As described above, according to the water heater with a bypass channel of the present invention,
By providing a bypass channel in the hot water supply heat exchanger channel and controlling the opening / closing of the solenoid valve in the bypass channel according to the above sequence, it is possible to prevent post-boiling that occurs when the water heater is used again after being temporarily suspended. It is possible to stabilize the tap water temperature. Moreover, cost can be reduced by using an inexpensive solenoid valve.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a water heater with a bypass water passage according to an embodiment of the present invention, FIG. 2 is a control sequence diagram of the water heater with a bypass water passage, and FIG. 3 is a configuration diagram of a conventional example. 3 ... Heat exchanger, 5 ... Solenoid valve, 10 ... Control circuit.

Claims (1)

[Claims] Claims: 1. A bypass water channel is provided in parallel with a water channel of a hot water heat exchanger, and a solenoid valve is provided in the bypass water channel. And the amount of post-boiling of the heat exchanger for hot water supply is calculated from the hot water supply interruption time, and when the amount of post-boiling is a certain amount or more, a control means for opening the solenoid valve of the bypass water channel for a certain time when reusing hot water is provided. A water heater with a bypass channel provided.