JPS6118355Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an after-boiling prevention device for a gas instantaneous water heater.

In gas instantaneous water heaters, during use (combustion)
The fins, combustion chamber, etc. are maintained at a high temperature by combustion gas, and hot water is generated by heat transfer by water flowing through the tube.

However, once the water flow is stopped, the gas supply is automatically stopped, but the amount of heat stored in the fins, combustion chamber, etc. is transferred to the hot water in the tube, causing a temperature rise (post-boiling). In severe cases, a boiling phenomenon may occur, and hot water may gush out from the hot water faucet when hot water is tapped.

This is sometimes noticeable in structures that do not have water cooling pipes in the combustion chamber.

For example, as shown in FIG. 4, a conventional gas instantaneous water heater has a structure in which a multi-tube heat absorber a with fins a' is simply connected to a water supply pipe d and a hot water supply pipe e. With this structure, when the water heater is in use (combustion)
When the water flow is stopped, the amount of heat stored in the fin A′ and the combustion chamber B is transferred to the hot water in the heat absorption tube C, and the temperature rises (post-boiling), and when hot water is re-discharged, the heated hot water directly comes out from the hot water tap g. Particularly in combustion chambers that do not have water cooling pipes, there is a risk of hot water spewing out and causing burns in extreme cases.

The after-boiling prevention device proposed in this invention is completely the same in design as the conventional multi-tube heat absorber with fins, but with some improvements, the structure is simple, there are no moving parts, the manufacturing cost is low, and it is highly effective. This is an innovative method.

The present invention will be described in detail below based on the example diagrams.
1 is an inner shell forming the combustion chamber 2 in the gas instantaneous water heater, 3 is a multi-tubular heat absorber disposed above the combustion chamber 2, and 4 is a fin 5 forming the heat absorber 3. It comes with a tube.

6 is a water supply pipe connected to the heat absorber 3; 7 is a hot water pipe that guides hot water discharged from the heat absorber 3 to a hot water tap 8; and 9 is a gas burner.

10 is a tube (tank) disposed above the heat absorber 3 to prevent boiling, and this tube 10
is connected to the water supply pipe 6 via the communication pipe 11, and the outlet 13 of the tube 10 is connected to the hot water supply pipe 7. Reference numeral 12 denotes a throttle (for example, an orifice) provided in the communication pipe 11, and the action of the throttle 12 adjusts the amount of water that reaches the inside of the tube 10 through the communication pipe 11.

Note that the shape of the tube 10 is not particularly limited.
Further, the aperture 12 is connected to the tube 10 via the communication pipe 11.
Since the amount of water entering the pipe is adjusted, for example, the diameter of the communication pipe 11 itself is made small to adjust the amount of water.
The throttle 12 may be omitted, and the water amount adjusting means is not particularly limited.

Next, to explain the operation of the present invention, when the gas instantaneous water heater is in use (during combustion), most of the supplied water enters the finch tube 4 in the heat absorber 3 from the water supply pipe 6 as shown in Fig. 2. , is heated by the gas burner 9, passes through the hot water supply pipe 7, and reaches the hot water tap 8, but a portion of the supplied water (the amount determined by the diameter of the throttle 12 and the water flow resistance ratio of the finch tube 4) flows from the communication pipe 11 to the throttle 12.
through the tube 10 for preventing after boiling,
The amount of bypass water rejoins the hot water in the hot water pipe 7 and reaches the hot water tap 8. The hot water and water from these two lines are mixed and discharged at a predetermined hot water temperature.

Next, when the water flow to the water heater that is in use (combustion) is stopped, the amount of heat stored in the fin 5 of the finch tube 4, the combustion chamber 2, etc. is transferred to the hot water in the finch tube 4 in the same way as described above. As a result, the temperature of the hot water rises (post-boiling), but natural convection occurs as shown in FIG. 3 due to the difference in density between the water in the tube 10 arranged above the heat absorber 3 to prevent post-boiling.
As a result, the hot water in the finch tube 4 loses heat to the water in the tube 10 for preventing after-boiling, and its temperature decreases, and over time, the water in the tube 10 is warmed and its temperature increases.

Thereby, the hot water in the finch tube 4 does not boil, and hot water does not spout out from the hot water faucet 8 when the hot water is re-discharged.

Figures 5 and 6 show the effect of implementing this device, which was confirmed by actually measuring the temperature rise of the water in the fin tube 4 and the water in the tube 10 for preventing after-boiling in a gas instantaneous water heater with a structure having no water cooling pipe in the combustion chamber 2. As is clear from Figure 5, the water temperature in the fin tube 4 rises sharply when the water supply is stopped, but immediately begins to drop in temperature, while as shown in Figure 6, the water temperature in the tube 10 begins to rise when the water supply is stopped, and gradually rises, stopping after about a few minutes.

From the above experimental results, the above-mentioned after-boiling prevention effect can be proven.

In addition, Figure 7 shows a gas instantaneous water heater having a structure that does not have a water cooling pipe in the combustion chamber in the same way as described above, after 1 minute and 2 minutes after the water flow is stopped once during use (during combustion). …
This is a graph that compares the value of the temperature rise due to after-boiling when hot water is re-discharged after 6 minutes (after-boiling temperature - set temperature) by experimentally determining and comparing the cases with and without the after-boiling prevention device. be. As is clear from FIG. 7, by installing the post-boiling prevention device of the present invention, there is an advantage that the post-boiling temperature rise can be reduced by about 3 to 6.5 degrees according to experimental values.

As described above, the present invention has the effect of solving the after-boiling problem, which has been a major problem in gas instantaneous water heaters, at low cost and using an extremely simple system that does not have any moving parts. In addition, since the heat absorber is not overheated due to post-boiling, there is no abnormal noise caused by the boiling phenomenon and there is no effect on the service life.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a gas instantaneous water heater implementing the present invention, Figs. 2 and 3 are explanatory diagrams of the operation, Fig. 4 is a schematic diagram of a conventional gas instantaneous water heater, and Figs. FIG. 6 and FIG. 7 are experimental results (graphs) for explaining the effects of implementing the present invention. 1...Inner shell, 2...Combustion chamber, 3...Heat absorber, 4
... Finch tube, 5 ... Fin, 6 ... Water supply pipe, 7 ... Hot water supply pipe, 8 ... Hot water tap, 9 ... Gas burner, 10 ... After-boiling prevention tube, 11 ...
Communication tube, 12... throttle, 13... tube outlet.

Claims (1)

[Scope of utility model registration request] In a gas instantaneous water heater, a tube (or tank) for preventing after-boiling is installed above the multi-tube heat absorber with fins, and this tube and the water supply pipe are connected through a communication pipe, and the other side is connected to the hot water supply pipe. An after-boiling prevention device in a gas instantaneous water heater that communicates with a pipe.