JP2011179779A - Twisted tube type heat exchanger for water heater and heat pump type water heater including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance reliability of lateral brazing by an automatic brazing machine and inexpensively perform lateral brazing by the automatic machine. <P>SOLUTION: This twisted tube type heat exchanger for a water heater includes: approximately cylindrical first water piping 2 wherein a tapered part 7 having a diameter contracted toward a tip is formed at one end and a spiral groove is formed on the outer periphery; approximately cylindrical second water piping 2 jointed to the tapered part 7 of the water piping and having a spiral groove formed on the outer periphery thereof; and refrigerant piping jointed along the spiral grooves of the first water piping and the second water piping. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a torsion tube heat exchanger for a water heater in which water pipes having spiral grooves formed on the outer peripheral part by twisting are processed, and in particular, a hot water supply having an improved connection part between water pipes The present invention relates to a torsion tube heat exchanger for a machine.

  The heat exchanger uses a torsion pipe with a spiral groove on the outer periphery as a water pipe, wraps the refrigerant pipe from the outer circumference along the spiral groove, and electrothermally joins the water pipe and the refrigerant pipe There is something that was made to form. In such a heat exchanger, water is continuously circulated through the water pipe, and the refrigerant is continuously circulated through the refrigerant pipe, whereby heat is exchanged between the water and the refrigerant. That is, in the heat exchanger, heat transfer occurs between the refrigerant and the water, whereby the temperature of the water can be adjusted to a predetermined temperature.

  For example, a pipe made of a water pipe and a refrigerant pipe joined by electrothermal joining (usually, the length of one pipe is about 5000 mm) is performed using, for example, phosphor copper solder. For the joining, a means called horizontal brazing is usually used. This lateral brazing is easily affected by gravity in addition to the capillary action. That is, it is difficult to ensure reliability when performing horizontal brazing using an automatic machine instead of a human hand. Therefore, in general, this horizontal brazing is performed by a person (hand brazing) to ensure reliability. However, hand brazing is also forced to depend on the skill level of the operator.

  As a means to solve such problems, one joint end of the pipe to be connected is formed into a shape that is reduced in diameter toward the end, and the other pipe is connected to the end so that the connection end is expanded toward the end. There has been proposed (for example, Patent Document 1) in which the taper portions are formed at the same taper angle so that the taper portions mesh with each other. Thereby, the clearance between the connection end portions described above is reduced, and more reliable hand brazing is possible.

  In addition, in the double pipe having the outer pipe and the inner pipe, the inner pipe is inserted into the outer pipe, and the longitudinal end portion of the outer pipe is brazed to the outer peripheral surface of the inner pipe. A double pipe having a configuration in which a caulking portion that is reduced in diameter and caulked to the inner pipe is formed at the end portion in the longitudinal direction of the outer pipe. It has been reported (for example, Patent Document 2).

  In this technique, an inner tube is inserted into an outer tube, and both tubes are caulked and fixed at a predetermined position. As a result, it is possible to prevent the longitudinal displacement between the outer tube and the inner tube, and to facilitate horizontal brazing or vertical brazing.

  Further, the inner surface of the end portion of the outer tube, which is the end in the longitudinal direction from the caulking portion of the outer tube and the inner tube, is formed with a tapered portion that is thinner toward the end. Therefore, it is possible to avoid a space for brazing the outer tube and the inner tube after the outer tube and the inner tube are fixed by caulking. In this way, a space for horizontal brazing or vertical brazing is secured, so that brazing can be reliably performed.

Japanese Patent Laid-Open No. 3-8560 (FIG. 2) JP 2007-155247 A (2 pages, 8 pages, 9 pages, FIGS. 3 and 4)

  As described above, it has been difficult from the viewpoint of reliability to use an automatic brazing machine for horizontal brazing between pipes of a conventional heat exchanger. In addition, there is a method of performing horizontal brazing surely by performing complicated processing on the piping, but the number of processing increases and costs are increased.

  The present invention has been made to solve the above-described problems, and has as its first object to increase the reliability of horizontal brazing using an automatic brazing machine. In addition to the first object, the second object is to carry out horizontal brazing with an automatic machine at low cost.

  The torsion tube heat exchanger for a water heater according to the present invention has a substantially cylindrical first shape in which a tapered portion that is reduced in diameter toward the tip is formed at one end and a spiral groove is formed at the outer periphery. 1 water piping, the substantially cylindrical 2nd water piping joined to the taper part of the said water piping, and the helical groove | channel being formed in the outer peripheral part, and the helical form of the said 1st water piping and the said 2nd water piping And a refrigerant pipe joined along the groove.

  According to the heat exchanger according to the present invention, it is possible to carry out horizontal brazing with high reliability and low cost using an automatic brazing machine.

1 is a schematic configuration diagram of a torsion tube heat exchanger for a water heater according to an embodiment of the present invention. It is explanatory drawing of the helical groove | channel formed in the water piping of the torsion pipe | tube type heat exchanger for hot water heaters concerning embodiment of this invention. It is an enlarged view of a mode that refrigerant piping was inserted in the spiral groove formed in the water piping of the twisted tube heat exchanger for hot water heaters concerning an embodiment of the invention. It is explanatory drawing of the taper part formed in the junction edge part of the water piping of the torsion pipe | tube type heat exchanger for water heaters which concerns on embodiment of this invention. It is sectional drawing of the ring-shaped wax used for joining of the torsion pipe | tube type heat exchanger for water heaters concerning embodiment of this invention. Test of brazing the water pipe of the torsion pipe heat exchanger for hot water heater according to the embodiment of the present invention while changing the taper angle of the taper portion of the water pipe using the brazing shown in FIG. Is the result of It is a schematic block diagram which shows the circuit structure of water and the refrigerant | coolant of the heat pump type water heater 100 which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a torsion tube heat exchanger for a water heater according to an embodiment of the present invention.
The torsion tube heat exchanger for a water heater according to the present embodiment includes at least a heat exchanger body 1 as shown in FIG.

  The heat exchanger main body 1 in the present embodiment includes a water pipe 2 through which water flows and a refrigerant pipe 3 joined along a spiral groove formed on the outer periphery of the water pipe 2. As will be described later, the refrigerant pipe 3 is wound and joined along a spiral groove formed in the water pipe. The water pipe connection inlet 5a and the water pipe 2 communicate with each other so that water enters the heat exchanger main body 1 from the water pipe connection inlet 5a and then flows into the water pipe 2. And after flowing through the water pipe 2, the water is discharged from the water pipe connection outlet 5b and used by the user.

  The refrigerant is configured to flow into the heat exchanger main body 1 from the refrigerant pipe connection inlet 6a, branch into three at the refrigerant branching portion 4a, and flow into the refrigerant pipe 3. That is, the refrigerant connection inlet 6a, the refrigerant distribution part 4a, and the refrigerant pipe 3 communicate with each other in this order. The refrigerant that has flowed through the refrigerant pipe 3 joins again at the refrigerant junction 4b and is discharged from the refrigerant pipe connection outlet 6b. That is, the refrigerant pipe 3, the refrigerant junction 4b, and the refrigerant connection outlet 6b communicate with each other in this order.

  FIG. 2 is an explanatory diagram of a spiral groove formed in a water pipe of a torsion tube heat exchanger for a hot water heater according to an embodiment of the present invention. The water pipe 2 is formed by processing a tubular member called an elementary pipe that allows a fluid to flow inside. Thereafter, the water pipe 2 is created by forming a spiral groove on the outer periphery of the base pipe. In general, the raw tube is often made of copper (phosphorus deoxidized copper), but the material is not particularly limited.

In forming and processing a spiral groove on the outer periphery of the raw tube, a cored bar (hard bar member) is inserted into the raw tube, one end of the raw tube is fixed, and the other end is rotated (twisted). As a result, the raw tube is twisted, and a spiral groove is formed in the outer peripheral portion. Moreover, since brazing is implemented in the both ends (part which connects water piping) of the water piping 2, a spiral groove shall not be formed.
Since high precision is required for processing to form the spiral groove, it is desirable that the longitudinal direction of the raw tube is straightened with high precision (straight in the longitudinal direction).

Further, the longest usable length in the longitudinal direction of the raw tube is desirably 6300 mm or less from the viewpoint of transportation and the length that can be installed in the twisting machine.
The length in the longitudinal direction of the raw tube in which a spiral groove is formed on the outer periphery is reduced by several tens of percent from the straight tube material before the formation. This means that in the process of twisting the tube and forming a spiral groove, the length of the tube is shortened. Thereby, when the total length of the water piping 2 incorporated in the heat exchanger main body 1 is 6000 mm or more, a plurality of water pipings 2 are inevitably connected.

  Further, as shown in FIG. 2, when joining the water pipes 2, one end of one water pipe has a tapered portion 7 whose diameter is reduced (details regarding the taper shape will be described later in FIG. 4). . The provision of the tapered portion 7 in the water pipe 2 is the main point of the present invention. One end of the other water pipe does not need to be particularly processed to expand the pipe (process to expand the joint of the other water pipe 2 so as to match the reduced diameter shape of the tapered portion 7). Good.

For example, as seen in the prior art, processing to expand the tube means that the number of processing points increases, so that a torsion tube heat exchanger for a water heater can be efficiently manufactured. It becomes inconvenient. Therefore, in this embodiment, in order to efficiently manufacture a torsion tube heat exchanger for a hot water heater, one end of the other water pipe is not processed to expand the pipe.
Then, as shown in FIG. 2, the taper portion 7 of the water pipe whose diameter is reduced toward the end is inserted into the other water pipe, and brazing is performed in that state to join.

  After joining the water pipes 2 in this way to the set dimensions, bending is performed so as to form an elliptical coil shape. Then, the refrigerant | coolant piping 3 is inserted along the groove | channel formed in the water piping 2 mentioned later. In order to improve the thermal conductivity of the water pipe 2 and the refrigerant pipe 3, a treatment (dipping) is applied to the bath in which the solder is melted to join each other. As other methods for joining the water pipe and the refrigerant pipe 3, there are a method in which solder is attached to the outside of the water pipe 2 and the refrigerant pipe 3, and a method in which a solder paste is applied. In any case, the water pipe 2 and the refrigerant pipe 3 are joined and incorporated in the heat exchanger body 1.

A water pipe connection inlet 5a is attached to the end of the water pipe 2 where water flows. For example, a pipe attached to the hot water storage tank 107 (which is described at the end of the embodiment, which temporarily stores water) is configured to communicate with the water pipe connection inlet 5a.
Further, a water pipe connection outlet 5b is attached to an end portion where water flowing through the water pipe 2 comes out. The water pipe connection outlet 5b is configured to communicate with, for example, a pipe toward the water storage tank 107.

Next, the spiral groove formed in the water pipe of this embodiment will be described in detail.
As shown in FIG. 2, crests 2 a and troughs 2 b are alternately and continuously formed in the water pipe, forming a spiral groove on the outer periphery of the water pipe 2. In the present embodiment, the spiral grooves formed on the outer periphery of the water pipe 2 are composed of three strips, and the intervals between the grooves are equal.

  Although the number of spiral grooves formed in the water pipe is not limited to three, if the number of spiral stripes is small, pressure loss is likely to occur in the refrigerant passing through the refrigerant pipe 3. That is, a stronger pressure is required to flow the refrigerant, and energy is wasted. In addition, when the number of spiral strips is small, the electric heating area is reduced, resulting in inefficient heat exchange.

  On the other hand, if the number of spiral stripes is too large, problems such as at least processing problems and costs arise. From the above, the number of spiral strips in the present embodiment is applied assuming that three strips are optimal. The pressure loss also depends on the inner diameter of the refrigerant pipe 3, but in the present embodiment, the inner diameter of the refrigerant pipe 3 is the same because the interval between the grooves is constant.

  FIG. 3 is an enlarged view of a state in which the refrigerant pipe 3 is fitted into a spiral groove formed in the water pipe of the torsion pipe heat exchanger for a hot water heater according to the embodiment of the present invention. How the refrigerant pipe 3 is wound around the spiral groove formed in the water pipe 2 shown in FIG. 2 will be described.

  In the present embodiment, as described above, three grooves are formed in a spiral shape on the outer periphery of the water pipe 2. In response to this, the refrigerant pipe 3 is branched into three independent pipes by a refrigerant branching portion 4a described later. The three independent refrigerant pipes 3 are fitted into three spiral grooves so that they do not cross or overlap each other.

  Here, as shown in FIG. 3, in order to simplify the description, the three independent refrigerant pipes 3 are referred to as a refrigerant pipe 3a, a refrigerant pipe 3b, and a refrigerant pipe 3c, respectively. The refrigerant pipe 3a is not fitted into a groove in which the refrigerant pipe 3b and the refrigerant pipe 3c are fitted, and is spirally wound around the water pipe 2 without intersecting or overlapping the refrigerant pipe 3b and the refrigerant pipe 3c. Similarly, the refrigerant pipe 3b and the refrigerant pipe 3c are fitted only in the respective defined grooves, and do not cross or overlap with other refrigerant pipes, and are wound around the water pipe 2 in a spiral shape.

As shown in FIG. 3, the refrigerant distribution part 4a is connected so as to communicate with the starting end of the refrigerant pipe 3 and the refrigerant pipe connection inlet 6a. The refrigerant that has flowed into the refrigerant distribution section 4a plays a role of dividing the refrigerant into the three refrigerant pipes 3 (three in the present embodiment).
The other end of the refrigerant pipe connection inlet 6a is connected to, for example, a compressor (see FIG. 8).

  On the other hand, the refrigerant junction 4b is connected to communicate with the end of the refrigerant pipe 3 (all three) and the refrigerant pipe connection outlet 6b. The refrigerant that has flowed into the refrigerant merging portion 6b plays a role of combining the flows that have been divided into the three refrigerant pipes 3 (three in the present embodiment) into one flow. The other end of the refrigerant pipe connection outlet 6b is connected to, for example, an expansion valve (see FIG. 8).

Next, joining of the water piping 2 in this Embodiment is demonstrated.
Normally, vertical brazing that is not easily affected by gravity is recommended for joining pipes. In other words, vertical brazing means that the upper and lower parts of the pipe joint have a uniform finish without unevenness. However, since the water pipe 2 in the present embodiment belongs to a long category as a target to be brazed, it is physically difficult to braze vertically. Therefore, the brazing in the present embodiment is premised on the lateral brazing.

  However, unlike vertical brazing, horizontal brazing is affected by gravity, causing unevenness at the upper and lower portions of the pipe joint, making uniform brazing difficult. In other words, horizontal brazing was performed manually by a skilled worker, and after lateral brazing, a visual check and a leak check were taken.

  However, ensuring the reliability of horizontal brazing is not completely dependent on skilled workers. In other words, it may be difficult to maintain the brazing reliability when the brazing worker has to be replaced. Therefore, it is necessary to train a large number of workers who are excellent in brazing technology, but this causes a problem that labor costs are increased. Moreover, when there are a plurality of joints in the water pipe 2, more skilled workers must be secured. In addition, for example, when there is a difference in the horizontal brazing time depending on the worker, there is a possibility that the production becomes inefficient.

  In order to cope with the above problems, it is conceivable to deal with brazing by an automatic machine. Among the brazing using automatic machines, the most popular are, for example, gas brazing, high-frequency brazing, and brazing in a furnace. Among these, in particular, in this embodiment, horizontal brazing using an automatic machine may be applied to high-frequency brazing (in this embodiment, horseshoe-shaped on both sides of the water pipe 2). A coil is prepared, and a current is passed through the coil to generate heat to melt and join the solder). This is a result of considering interference between other equipment and the high-frequency brazing machine.

  However, when performing horizontal brazing with a high-frequency brazing machine, it must be taken into account that the flowability of brazing differs between the upper part and the lower part of the joint of the water pipe 2 due to the influence of gravity. The flowability of this wax is at least a clearance that affects the capillary phenomenon (clearance at the joint between the water pipes 2 to be joined), how to apply heat (the amount of heat to be applied and the selection of the heating location), the material of the wax, Depending on the shape of the.

  For example, in order to perform highly reliable horizontal brazing in high-frequency brazing, it is necessary to devise a method in which the brazing sufficiently penetrates into the brazing location on the brazing property described above, particularly on the upper side. For example, a means of increasing the content ratio of Ag contained in the brazing material can be considered, but there is a problem that the cost is significantly increased. Therefore, in this embodiment, the flowability of the solder is ensured by optimizing the shape of the joint end of the water pipe 2 and the shape of the brazing using an automatic machine (high frequency brazing machine).

Drawing 4 is an explanatory view of taper part 7 formed in the joint end part of the water piping of the torsion pipe type heat exchanger for water heaters concerning an embodiment of the invention.
When the tapered portion 7 is formed at the joining end portion of the water pipe 2, the diameter of the water pipe is reduced once by the circumferential portion A as shown in FIG. The length in the longitudinal direction from the circumferential portion A to the circumferential portion B is not particularly limited. However, after brazing, it is preferable that the reliability does not arise even if water is circulated from the circumferential portion A to the circumferential portion B.

  The diameter-reduced portion from the circumferential portion A to the circumferential portion B of the water pipe 2 is reduced so as to be equal to or smaller than the inner diameter of the other water pipe 2. The diameter of the circumference B is reduced again at a predetermined angle. The tapered portion 7 of the present embodiment refers to a substantially cylindrical portion from the circumferential portion B to the circumferential portion C shown in FIG.

  As shown in FIG. 4, the taper angle of the taper portion 7 of the present embodiment includes a dotted line aa parallel to the longitudinal direction and passing through the circumferential portion A, and a substantially cylindrical portion from the circumferential portion A to the circumferential portion B. It is an angle formed with the line segment represented by the vertical section. In that case, a taper angle shall measure the direction which goes to the central axis of the water piping 2 from line segment aa. How to change the taper angle of the taper portion 7 in this embodiment will be described later.

Next, the wax shape used for joining the water pipe 2 in the present embodiment will be described.
FIG. 5 is a cross-sectional view of a ring-shaped brazing used for joining a torsion tube heat exchanger for a hot water supply apparatus according to an embodiment of the present invention. As shown in FIG. 5, the shape of the wax used in the present embodiment is thicker on the upper side and thinner toward the lower side. That is, the shape is a ring shape with a different diameter. When the thickness of the thickest part at the top is T and the thickness of the thinnest part at the bottom is t, it is processed so as to satisfy the relationship 2t>T> t.

  Note that the positional relationship between the thinnest part and the thinnest part of the ring-shaped wax used in the present embodiment is opposed to each other on an opposing straight line. In the present embodiment, the length of the ring-shaped wax in the longitudinal direction is not particularly limited, but may be adjusted according to the length of the joint portion, for example. Similarly, the inner diameter and outer diameter of the ring-shaped wax in the present embodiment may be adjusted according to the thickness of the water pipe 2 to be connected.

  By adopting such a wax shape, it is possible to obtain an effect that the way of heat transfer on the upper side is slightly delayed from that on the lower side, so it is possible to suppress the upper side wax from flowing excessively to the lower side due to the influence of gravity. As a result, uniform horizontal brazing can be performed. Thereby, the reliability of horizontal brazing is improved.

  FIG. 6 shows the joining of the water pipe of the torsion tube heat exchanger for a hot water heater according to the embodiment of the present invention, while changing the taper angle of the taper portion 7 of the water pipe using the wax described in FIG. It is the result of the test which carried out horizontal brazing. The test of the same conditions was implemented 4 times with respect to one taper angle. In FIG. 6, the horizontal axis represents the taper angle of the taper portion 7, and the vertical axis represents the upper row flow rate. The taper angle of the taper portion 7 is defined as described above. The upper brazing flow rate is obtained by quantifying the degree of brazing by cutting the upper and lower surfaces of the brazed sample in cross section. Normally, it is desired that the brazing flow rate be 80% or more for brazing with high reliability.

  As shown in FIG. 6, from the results of the test, the range where the taper angle of the taper portion 7 is 0 degree or more and less than 5 degrees occupies most cases where the low flow rate changes to about 50%. It is hard to say that the brazing is high. However, when the taper angle of the taper portion 7 is in the range of 5 degrees or more and 10 degrees or less, the total number of wax flow rates exceeds 80%, and it can be said that the brazing is highly reliable. Further, it can be seen that when the taper angle of the taper portion 7 is larger than 10 degrees and 15 degrees or less, the clearance of the joint portion between the water pipes to be joined becomes large, so that the low flow rate is deteriorated.

  From the above, the heat exchanger 1 according to the present embodiment uses the ring-shaped wax having the different diameter shown in FIG. 6, and the taper portion 7 of one water pipe has a taper angle of 5 degrees or more and 10 degrees. By setting the following range, the brazing flow property is stabilized, and the reliability of the lateral brazing by the high frequency brazing machine (automatic brazing machine) is ensured. Further, the processing required for the joint portion of the water pipe 2 in the present embodiment is sufficient to provide the above-described tapered portion, and the cost can be suppressed.

Finally, the heat pump type water heater 100 provided with the heat exchanger body 1 of the present embodiment will be described.
FIG. 7 is a schematic configuration diagram showing a circuit configuration of water and refrigerant in the heat pump type hot water heater 100 according to the embodiment of the present invention. Based on FIG. 7, the example of a structure and operation | movement of the heat pump type water heater 100 is demonstrated. The heat pump type hot water heater 100 includes at least a heat pump unit 101 and a hot water storage unit 102. The heat pump unit includes at least a heat exchanger body 1 (water heating side heat exchanger), an expansion device 103, a compressor 104, an air side heat exchanger 105, and a pump. The hot water storage unit 102 includes at least a hot water storage tank 107.

  As shown in FIG. 7, the heat pump unit 101 includes a heat exchanger body 1 (water heating side heat exchanger), an expansion device 103, an air side heat exchanger 105, and a compressor 104. Are connected in sequence.

  The hot water storage unit 102 temporarily stores water heated by the heat exchanger main body (water heating side heat exchanger), and when the user uses it, for example, the water heated in a faucet or the like is stored. It can be supplied.

  The heat exchanger body 1 (water heating side heat exchanger) functions as a condenser, performs heat exchange between the refrigerant flowing through the refrigerant pipe 3 and the water flowing through the water pipe 2, and adjusts the temperature of the water To do.

  The air-side heat exchanger 105 functions as an evaporator, performs heat exchange between the refrigerant that is conducted through the refrigerant pipe 110 and air, and vaporizes and gasifies the refrigerant.

  The expansion device 103 decompresses and expands the refrigerant conducted through the refrigerant pipe 110. The throttling device 103 may be composed of, for example, a capillary tube or a solenoid valve.

  The pump 106 functions to suck up the water stored in the hot water storage tank 107 and send the water to the heat exchanger main body 1 (water heating side heat exchanger).

  Next, the operation of the heat pump type water heater 100 will be described. When the heat pump hot water heater 100 is activated, the compressor 104 can first use a gaseous refrigerant (for example, a single refrigerant, a non-azeotropic refrigerant mixture, or a natural refrigerant such as carbon dioxide or propane). .) To increase the temperature and pressure of the refrigerant. Next, the refrigerant is fed into the heat exchanger main body 1 and exchanges heat with water via the water pipe 2. As a result, the temperature of the refrigerant decreases. Next, the pressure of the refrigerant that has been sent to the capillary tube and increased to a high pressure is lowered and liquefied.

  Thus, the liquefied low-temperature refrigerant is sent to the air-side heat exchanger 105. Air is blown onto the refrigerant by a fan or the like provided in the air-side heat exchanger 105. Thereby, the refrigerant absorbs heat from the blown air and vaporizes. The refrigerant that has passed through the air-side heat exchanger 105 is sent again to the compressor. By performing this cycle continuously, the heat pump unit 101 can warm water and store the warmed water in the hot water storage unit 102. In this way, for example, heated water can be supplied to an indoor faucet.

  1 heat exchanger main body, 2 water piping, 2a crest, 2b trough, 3 refrigerant piping, 3a refrigerant piping, 3b refrigerant piping, 3c refrigerant piping, 4a refrigerant distribution portion, 4b refrigerant junction, 5 refrigerant piping connection port, 5a Water pipe connection inlet, 5b Water pipe connection outlet, 6a Refrigerant pipe connection inlet, 6b Refrigerant pipe connection outlet, 7 Tapered part, A circumference part, B circumference part, C circumference part, 100 Heat pump type hot water heater, 101 Heat pump unit, 102 hot water storage unit, 103 expansion device, 104 compressor, 105 air side heat exchanger, 106 pump, 107 hot water storage tank.

Claims (5)

A substantially cylindrical first water pipe in which a tapered portion that is reduced in diameter toward the tip is formed at one end, and a spiral groove is formed in the outer peripheral portion;
A substantially cylindrical second water pipe joined to the tapered portion of the first water pipe and having a helical groove formed on the outer periphery;
A torsion tube heat exchanger for a hot water heater, comprising: a refrigerant pipe joined along a spiral groove of the first water pipe and the second water pipe. The torsion tube heat exchanger for a hot water heater according to claim 1, wherein the taper angle of the tapered portion is in a range of 5 degrees to 10 degrees. The hot water supply according to claim 1 or 2, wherein the joining portion is joined by using a substantially cylindrical ring having a different diameter ring shape in which an upper portion of a longitudinal section is thick and thin toward a lower portion. Twisted tube heat exchanger for machine. The said joining part is joined using a high frequency brazing machine. The torsion pipe | tube type heat exchanger for water heaters as described in any one of Claims 1-3 characterized by the above-mentioned. A heat pump type hot water heater comprising the torsion tube heat exchanger for hot water heater according to any one of claims 1 to 4.

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