JPH07324811A - Heat-exchange part of proportional control type hot-water heater - Google Patents

Abstract

PURPOSE:To prevent drain from attaching to a heat-exchange pipe or prevent boiling inside the heat-exchange pipe when the combustion is low relating to a proportional control type hot-water heater. CONSTITUTION:A-double pipe 4a is welded to a heat-exchange pipe 4 located in a passageway A for combustion gas. 0pening/closing valves 6, 7 are provided before and after the heat-exchange pipe 4 respectively so as to feed water selectively to the double pipe 4a and by switching the valves 6, 7 the part through which water flows is increased or decreased. When the flow rate of water and the amount of combustion in the hot-water heater are small, water is made to flow through either the heat-exchange pipe 4 or the double pipe 4a so that the heat-exchange volume is decreased and excessive decrease of the temperature of the exhaust gas is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a heat exchange section of a proportional control type hot water supply apparatus, such as a direct connection type hot water supply apparatus having a small amount of stored hot water, in which the burner combustion amount is varied according to the amount of the supplied water.

[0002]

2. Description of the Related Art There is known a water heater in which a heat exchange pipe is attached to a combustion gas passage of a burner and the heat exchange pipe is directly connected to a water supply. This type of water heater is used for the amount of water passing through the heat exchange pipe. The burner combustion amount is changed accordingly, and it is said to be a proportional control type water heater.

[0003]

When the amount of water passing through the heat exchange pipe located in the combustion gas flow passage is increased or decreased, the proportional control type water heater in which the combustion amount of the burner also increases or decreases is located in the combustion gas flow passage. Since the surface area of the heat exchange pipe 2 is constant, the amount of water passing through the heat exchange pipe is reduced when the heat power is small, and the heat exchange efficiency may be too high and the hot water may boil in the heat exchange pipe. Further, there is a drawback that the exhaust temperature is lowered and drain water is attached to the outer surface of the heat exchange pipe, which causes deterioration of the heat exchange pipe, and a countermeasure is required.

[0004]

In order to solve the above problems, the present invention provides a water supply pipe 1 viewed from outside the water heater.
And a proportional control type water heater in which a heat exchange pipe 4 looking into the combustion gas passage A of the burner 3 for varying the combustion amount and a hot water supply pipe 2 looking out of the water heater are connected in series,
The heat exchange pipe 4 in the combustion gas flow path A is provided with a double pipe 4a in parallel, and on-off valves 6 and 7 are provided in front of and behind the heat exchange pipe 4,
By switching the opening / closing valves 6 and 7, the flow passage of the flowing water is switched between the heat exchange pipe 4 and the double pipe 4a, and when the amount of flowing water and the combustion amount are large, the flowing water flows through the heat exchange pipe 4 and the double pipe 4a. The heat exchange part structure of the proportional control type water heater that flows through the whole and flows through one of the heat exchange pipe 4 or one of the multiple pipes 4a when the amount of flowing water and the amount of combustion are small, and the heat exchange efficiency is appropriately lowered,
This prevents boiling and drainage in the heat exchange pipe 4.

Further, the heat exchange pipe 4 and the multiple pipe 4a are made of metal pipes and are closely contacted with each other by welding or the like, and the heat exchange pipe 4 and the multiple pipe 4a are connected by a communication passage 8.8a. Even when the water flow occurs only in one of the heat exchange pipe 4 and the double pipe 4a, the heat conduction between the two pipes 4 and 4a is improved and the temperatures of both pipes are made uniform.

[0006]

The proportional control type water heater of this type uses the burner 3 capable of varying the combustion amount, and operates the burner 3 by calculating the water amount and heat amount required by the water heater in a well-balanced manner. , The heat exchange pipe 4 in the combustion gas passage A
The double pipe 4a is located, and the open / close valves 6 and 7 provided in front of and behind the heat exchange pipe 4 allow the flowing water to pass through the heat exchange pipe 4 and the double pipe 4a when the combustion amount and the flowing water amount are large. When the amount of combustion is small and the water flow is small, the heat exchange pipe 4 and the double pipe 4a
The heat exchange efficiency is adjusted by switching so as to pass any of the above.

[0007]

EXAMPLE A configuration will be described below with reference to the drawings showing an example. 3 is a burner of a water heater capable of varying the combustion amount in a plurality of stages such as large, medium, small, and stopped, and A is a combustion flame of the burner 3. It is a combustion gas flow path into which combustion gas is sent, and communicates with the flue 9 and the exhaust port 10.

Reference numeral 4 is a heat exchange pipe for exchanging heat by looking into the combustion gas passage A, and a water supply pipe 1 directly connected to the water supply.
And the hot water supply pipes 2 that communicate with the hot water faucet, respectively, and meander in the combustion gas passage A so as to effectively receive the combustion heat. Reference numeral 4a denotes a double pipe which is arranged in parallel so that the volume of water passing through the heat exchange pipe 4 can be changed.
8a is a communication passage that connects the heat exchange pipe 4 and the double pipe 4a, respectively, and when running water goes straight through the heat exchange pipe 4 by opening / closing the open / close valves 6 and 7 attached to the heat exchange pipe 4. And the case of flowing also to the double pipe 4a.

Further, the heat exchange pipe 4 and the double pipe 4a arranged in parallel
Is made of metal, and if the close contact portion 4b is formed by brazing and welding each other, it is conducted by the low-temperature water passing through the heat exchange pipe 4 even when water is not passed through the double pipe 4a, Both the heat exchange pipe 4 and the double pipe 4a maintain a substantially uniform temperature, and it is possible to prevent boiling in the double pipe 4a when water is not passed. Further, when the amount of water flow and the amount of combustion are small, water is not passed through the double pipe 4a and heat is exchanged only by the heat exchange pipe 4, so the heat exchange efficiency is slightly reduced, but the exhaust gas temperature is lowered and exhaust gas is drained. It can be prevented.

Reference numeral 5 denotes a water amount sensor provided between the water supply pipe 1 and the heat exchange pipe 4, which controls the water heater by the amount of water flowing according to the amount of hot water used by opening the hot water faucet. The sensor 5 detects the water flow rate and sends a water flow rate signal to the controller of the water heater to change the combustion amount of the burner 3 in multiple stages. Further, temperature sensors 12 and 13 may be provided in the middle of the water supply pipe 1 and the hot water supply pipe 2 to output signals of water temperature and hot water temperature to change the combustion amount of the burner 3.

The on-off valves 6 and 7 are mounted in proper positions before and after the heat exchange pipe 4 and the double pipe 4a in the combustion gas flow passage. Generally, electromagnetic valves are used. When one is open, the other is closed. I am trying. For example, the solid line arrow and the dotted line arrow in FIG. 2 indicate the flow of water, and when the open / close valve 6 is closed and the open / close valve 7 is open, the water flows from the inlet side of the heat exchange pipe 4 to the communication passage 8 as shown by the solid line arrow.・ Communication passage 8a through double pipe 4a and open / close valve 7
The water flows through the heat exchange pipe 4 and the outlet side of the heat exchange pipe 4, and water flows through the entire heat exchange pipe 4 and the multiple pipe 4a. Further, when the open / close valve 6 is open and the open / close valve 7 is closed, water does not flow into the double pipe 4a as indicated by a dotted arrow, but passes through the heat exchange pipe 4 directly via the open / close valve 6. Therefore, the heat exchange efficiency can be adjusted by increasing or decreasing the heat exchange volume between water and combustion gas.

Reference numeral 11 designates a plurality of fins provided outside the heat exchange pipe 4 and the double pipe 4a in parallel with the flow direction of the combustion gas in order to efficiently absorb the combustion heat, and 14 constitutes a combustion gas passage A. There may be a case where a part of the heat exchange pipe 4 is wound and welded inside or outside the combustion cylinder 14 in the combustion cylinder.

[0013]

As described above, according to the present invention, the heat exchange pipe 4 of the proportional control type water heater for increasing and decreasing the amount of hot water used and the amount of combustion.
In addition, since the double pipe 4a that allows water to flow or not to flow by switching the open / close valves 6 and 7 is provided, and the flow passages for flowing water are increased / decreased depending on the amount of combustion, especially during small combustion (when a small amount of water is flowing). In the above, the conventional defect that drain water adheres to the surface of the heat exchange pipe 4 is eliminated.

Further, since the heat exchange pipe 4 and the double pipe 4a are closely contacted with each other, regardless of whether water is passed through the double pipe 4a or not.
The temperatures of both the heat exchange pipe 4 and the double pipe 4a are almost the same,
Even if water is not passed through the double pipe 4a during small combustion, the double pipe 4a
The water that stays inside does not boil and is useful in combination with the prevention of drain water generation.

[Brief description of drawings]

FIG. 1 is a sectional view of an oil water heater showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of an embodiment of the present invention, showing a state of water flow.

[Explanation of symbols]

 1 water supply pipe 2 hot water supply pipe 3 burner 4 heat exchange pipe 4a double pipe 5 water amount sensor 6 on-off valve 7 on-off valve 8 communication passage 8a communication passage A combustion gas flow passage

Claims (2)

[Claims] 1. A water supply pipe 1 viewed from the outside of a water heater, a heat exchange pipe 4 viewed in a combustion gas passage A of a burner 3 for varying a combustion amount, and an outside of the water heater. In the proportional control type water heater in which the desired hot water supply pipe 2 is connected in series, the heat exchange pipe 4 in the combustion gas passage A has a double pipe 4a.
Are provided in parallel, and opening / closing valves 6 and 7 are provided in front of and behind the heat exchange pipe 4, and the passage passage of the running water is switched between the heat exchange pipe 4 and the multiple pipe 4a by switching the opening / closing of the opening / closing valves 6 and 7. When the amount of flowing water and the amount of combustion are large, the flowing water flows through all of the heat exchange pipe 4 and the complex pipe 4a, and when the amount of flowing water and the amount of combustion is small, one of the heat exchange pipe 4 and the complex pipe 4a flows. The heat exchange part structure of the proportional control type water heater characterized by the above. 2. The heat exchange pipe 4 and the multiple pipe 4a are made of a metal pipe and are in close contact with each other by welding or the like, and the heat exchange pipe 4 and the multiple pipe 4a are connected by a communication passage 8.8a. The heat exchange part structure of the proportional control type water heater according to claim 1.