A volumetric gas water heater

Abstract

The application discloses a volumetric gas water heater, which comprises a shell, an air inlet device, a combustion chamber and a heat exchange coil set. The heat exchange coil set is formed by spirally arranging a plurality of heat exchange pipes from top to bottom. The heat exchange pipe comprises a first buffer pipe, a second buffer pipe, a spiral pipe and an output pipe connected in sequence. The first buffer pipe is connected with the combustion chamber and arranged vertically. The second buffer pipe is bent from one end of the first buffer pipe to the direction of the spiral pipe. The angle formed by the second buffer pipe and the first buffer pipe is larger than the angle formed by the spiral pipe and the first buffer pipe. The volumetric gas water heater has the first buffer pipe and the second buffer pipe combined in the heat exchange coil set. When the flue gas is sprayed, the volumetric gas water heater has a good multi-stage buffering effect, so that the flue gas can flow in the spiral pipe well and cannot be back-flushed into the combustion chamber to cause insufficient combustion. Meanwhile, the volumetric gas water heater can have a good heat exchange effect between the flue gas and the pipe wall, thereby further improving the heat efficiency of the water heater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas water heaters, in particular to a volumetric gas water heater. BACKGROUND

[0002] The gas water heater is a device that uses gas as energy, heats water through the heat generated by gas combustion, and makes the water temperature meet the requirements of life, heating, production process, etc. The volumetric gas water heater refers to a gas water heater with a container for storing hot water inside and as a part of the whole water heater. Due to the large volume of the volumetric gas water heater, it can meet the requirements of a large amount, continuous and comfortable water use, and is suitable for high-end residential buildings, apartments, restaurants, schools, hotels, factories, commercial office buildings, hospitals, entertainment and leisure places and many other places.

[0003] At present, the volumetric gas water heater includes two combustion modes of bottom combustion and top combustion; the bottom combustion mode is to inject gas from the bottom of the water heater, then ignite and burn to heat cold water, that is, the flue gas flows from bottom to top; the top combustion mode is to inject the mixed gas of gas and air from the top of the water heater into the combustion cylinder, ignite and burn in the combustion chamber, then the high-temperature flue gas flows out along the heat exchanger and exchanges heat with cold water to heat the cold water, and finally the flue gas after heat exchange flows out from the bottom, that is, the flue gas flows from top to bottom.

[0004] In the prior art, the heat exchanger of the volumetric gas water heater is mostly in the form of straight pipe or coil pipe.(1) The straight pipe heat exchanger generally adopts a bottom combustion mode. In order to prevent the generation of condensed water and cause corrosion of the water heater, the exhaust gas temperature is relatively high, so that the water heater has the problem of low thermal efficiency. Patent CN216897838U discloses a full-premixed combustion wave-shaped fire tube combustion water heater, which sets the heat exchange pipe of the straight pipe heat exchanger in a wave shape, so that it is applied to a vertical combustion mode. However, in order to buffer the pressure of the flue gas, the disc pipe at both ends is provided with a buffer pipe plate. The pipe plate is a flat plate structure, which can buffer the impact of the flue gas on one hand, and can facilitate the installation of the disc pipe and the distribution of the flue gas on the other hand. However, due to the relatively small combustion chamber of the heat exchanger with such a structure, the space required for the flue gas to flow in the combustion chamber is also relatively small. When the flue gas generated by combustion is relatively large, the flue gas flow is prone to be poor, thereby causing incomplete combustion, and even combustion extinguishment.(2) The coil pipe heat exchanger spirally coils from top to bottom with a disc pipe, and outputs outward after heat exchange with water. Patent CN217357552U discloses a double-path disc pipe double-face enamel full-premixed volumetric water heater, which increases a relatively long vertical flue gas buffer channel at the bottom of the combustion chamber, thereby increasing the space required for the flue gas to flow. Then, the flue gas is heat-exchanged with water along the two disc pipes. The two disc pipes are in a stacked structure, and form a relatively dense spiral coil to increase the residence time of the flue gas. However, since the high-temperature flue gas first flows into the flue gas buffer channel from top to bottom, when the high-temperature flue gas flows to the bottom of the flue gas buffer channel, most of the high-temperature heat has been transferred to the water. Then, the flue gas flows into the disc pipe from bottom to top, and the disc pipe flows from top to bottom, so that the heat exchange efficiency of the flue gas is relatively low, and the temperature of the flue gas flowing out is still relatively high. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the present application provides a volumetric gas water heater to solve the above-mentioned conventional problems. The present application improves the structure of the disc pipe and the water heater, so that the heat exchange effect and the flue gas buffering effect are both good, and the thermal efficiency of the water heater is further improved.

[0006] The present application adopts the following technical solutions:

[0007] A volumetric gas water heater comprises:

[0008] A housing with a water storage cavity, the housing is provided with a water inlet connector, a water outlet connector and a flue gas outlet connector; the water inlet connector and the water outlet connector are both connected with the water storage cavity, and the water inlet connector and the flue gas outlet connector are both arranged at the lower end of the housing, and the water outlet connector is arranged at the upper end of the housing;

[0009] An air inlet device is installed at the top of the housing, and is used for inputting combustible mixed gas;

[0010] a combustion chamber arranged in the water storage cavity, a combustion cylinder being arranged on the top of the combustion chamber and being connected with the air inlet device; and

[0011] at least one heat exchange coil group being arranged at the bottom of the combustion chamber, the heat exchange coil group being formed by a plurality of heat exchange pipes spirally arranged from top to bottom, the heat exchange pipes including a first buffer pipe, a second buffer pipe, a spiral pipe and an output pipe connected in sequence, the first buffer pipe being connected with the combustion chamber and being arranged vertically, the second buffer pipe being bent from one end of the first buffer pipe to the spiral pipe in a rotating direction, the angle between the second buffer pipe and the first buffer pipe being larger than the angle between the spiral pipe and the first buffer pipe, and the output pipe being arranged in the bottom of the shell and being connected with the flue gas outlet.

[0012] Preferably, the angle between the second buffer pipe and the first buffer pipe is an obtuse angle, and the angle between the spiral pipe and the first buffer pipe is an obtuse angle.

[0013] Preferably, the angle between the second buffer pipe and the first buffer pipe is 145°-160°, and the angle between the spiral pipe and the first buffer pipe is 100°-130°.

[0014] Preferably, the spiral lengths of the spiral pipes are the same and the spiral pipes are spirally arranged from top to bottom to form a structure of layers stacked one above another, and the spiral pipes have spiral gaps therebetween.

[0015] Preferably, the number of the heat exchange coil groups is three, the heat exchange coil groups are uniformly distributed from inside to outside, and the heat exchange coil groups have flow gaps therebetween.

[0016] Preferably, the outer diameter of the innermost heat exchange coil group is smaller than the outer diameter of the combustion chamber, and the outer diameter of the middle heat exchange coil group is larger than the outer diameter of the combustion chamber.

[0017] Preferably, the combustion chamber is provided with a combustion chamber upper end cover and a combustion chamber lower end cover, and the combustion chamber upper end cover and the combustion chamber lower end cover are both arranged in an elliptical shape.

[0018] Preferably, the lower end of the shell is provided with a flue cylinder seat, the flue cylinder seat including a seat body, a heat insulation plate and a smoke blocking ring, the smoke blocking ring being arranged on the heat insulation plate and dividing the upper end of the seat body into an inner smoke discharge channel and an outer smoke discharge channel, the smoke blocking ring being provided with a smoke discharge opening, and the smoke discharge opening and the flue gas outlet being arranged oppositely.

[0019] Preferably, the shell is provided with a shell upper end cover and a shell lower end cover, and the shell upper end cover and the shell lower end cover are both arranged in an elliptical shape.

[0020] Preferably, a heat-insulating sealing plate is provided at the connection between the air intake device and the combustion chamber, and the heat-insulating sealing plate is an aluminum silicate plate.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The storage-type gas water heater of the present invention improves the heat exchange coil assembly. The heat exchange coil assembly, consisting of a first buffer tube, a second buffer tube, a spiral tube, and an output tube, forms a better multi-stage buffering effect when the flue gas is ejected. The flue gas is continuously input into the spiral tube, where it exchanges heat with the water in the storage chamber before being output to the outside. This allows the flue gas to flow well within the spiral tube, preventing it from flowing back into the combustion chamber and causing incomplete combustion. At the same time, it also has a better heat exchange effect with the tube wall, thereby further improving the thermal efficiency of the water heater. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a storage gas water heater according to a preferred embodiment of the present invention;

[0024] Figure 2 for Figure 1 The diagram shown is a cross-sectional view of a storage-type gas water heater.

[0025] Figure 3 for Figure 1 The diagram shows the internal structure of a storage-type gas water heater, in which part of the outer casing is not shown;

[0026] Figure 4 for Figure 1 The top view of the smoke box holder shown.

[0027] In the diagram: 10. Outer shell; 11. Water inlet pipe; 12. Water outlet pipe; 13. Flue gas outlet pipe; 14. Smoke box base; 140. Heat insulation plate; 141. Smoke baffle ring; 15. Magnesium rod; 16. Ignition electrode; 17. Ion probe; 18. Water pressure relief valve; 19. Drain pipe; 20. Air inlet device; 21. Heat insulation sealing plate; 30. Combustion chamber; 31. Combustion cylinder; 40. Heat exchange coil assembly; 41. First buffer tube; 42. Second buffer tube; 43. Coiled tube; 44. Output pipe. Detailed Implementation

[0028] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] In the description of the present application, it needs to be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can be explicitly or implicitly included at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] In the description of the present application, it needs to be understood that when an element is considered to be "connected" to another element, it can be directly connected to another element or there can be an intermediate element. In contrast, when the element is referred to as "directly" connected to another element, there is no intermediate element.

[0031] Please refer to Figures 1-4 A positive displacement gas water heater for using gas as energy source, heating water by heat generated by gas combustion, specifically, the positive displacement gas water heater comprises a housing 10 with a water storage cavity, an air inlet device 20, a combustion chamber 30, at least one heat exchange coil group 40 and a control system.

[0032] The housing 10 is the water storage housing of the whole water heater, which is generally cylindrical. The housing 10 has a water storage cavity. Tap water or pure water (purified water) is poured into the water storage cavity of the housing 10, and hot water is stored while being heated, which is convenient for subsequent use of a large amount of hot water. In one embodiment, the housing 10 is provided with a water inlet connector 11, a water outlet connector 12 and a flue gas outlet connector 13. The water inlet connector 11 and the water outlet connector 12 are both connected to the water storage cavity. The water inlet connector 11 and the flue gas outlet connector 13 are both arranged at the lower end of the housing 10. The water outlet connector 12 is arranged at the upper end of the housing 10. The tap water pipe or the soft water pipe is connected to the water inlet connector 11, and then the cold water is input into the water storage cavity from bottom to top for heating. The hot water pipe is connected to the water outlet connector 12, and then the hot water is output, forming a water heating system. The number of the water inlet connector 11 is two. Alternatively, the housing 10 is provided with a housing upper end cover and a housing lower end cover. The housing upper end cover and the housing lower end cover are both arranged in an elliptical shape, so as to facilitate the installation of various components and improve the sealing performance of the water storage cavity. For example, the housing and the housing upper end cover and the housing lower end cover are made of stainless steel, which can be expanded and connected, greatly improving the work efficiency. The elliptical structure of the end cover not only solves the problem of pressure bearing structure, but also greatly reduces the thickness of the plate material and the consumption of steel material, and has better sealing performance.

[0033] In order to vertically install the housing 10, the lower end of the housing 10 is provided with a flue gas box cylinder seat 14, so that the housing 10 can be better vertically installed in cooperation with the flue gas box cylinder seat 14. Specifically, as shown in Figure 4As shown, the smoke box cylinder seat 14 includes a seat body, a heat insulation plate 140 and a smoke blocking ring 141, the smoke blocking ring 141 is arranged on the heat insulation plate 140 and divides the upper end of the seat body into an inner smoke discharge passage and an outer smoke discharge passage, the smoke blocking ring 141 is provided with a smoke discharge opening, and the smoke discharge opening is oppositely arranged with the smoke outlet connecting pipe 13. That is, the shell 10, through the effects of the heat insulation plate 140 and the smoke blocking ring 141, on the one hand, can buffer the flow speed of the flue gas, so that it has a longer residence time in the heat exchange coil group 40, and on the other hand, the flue gas staying on the heat insulation plate 140 can preheat the cold water in the lower end cover of the shell, and at the same time, the flue gas can be separated from the ground through the heat insulation plate 140, so as to avoid the heat transfer to the ground.

[0034] In other embodiments, as shown in Figure 1 As shown, the shell 10 is also provided with a water pressure relief valve, a magnesium rod 15, a first water temperature controller, a water level electrode, an ignition electrode 16, an ion probe 17, a water pressure relief valve 18 and a blowdown pipe 19, and the water pressure relief valve, the magnesium rod 15, the first water temperature controller, the water level electrode, the ignition electrode 16 and the ion probe 17 are all arranged on the upper end cover of the shell. The water pressure relief valve is used to open when the pressure in the shell 10 is too high and exceeds the set threshold of the water pressure relief valve, and then the water pressure in the shell 10 is discharged. The magnesium rod 15 is used to protect the combustion chamber 30, avoid the corrosion phenomenon of the surfaces of the combustion chamber 30 and the heat exchange coil group 40 in contact with water, and improve the heat exchange efficiency of the combustion chamber 30 and the heat exchange coil group 40 with water. The first water temperature controller is used to detect the water temperature of the upper part in the shell 10, the water level electrode is used to detect the water level in the shell 10, the ignition electrode 16 is used for ignition in the combustion chamber 30, and the ion probe 17 is used to detect the flame condition in the combustion chamber 30. The water pressure relief valve 18 is arranged on the upper end side of the shell 10 and is used to detect the water pressure in the shell 10; the blowdown pipe 19 is arranged at the bottom of the lower end cover of the shell and is used to discharge the water in the shell 10 when maintenance is needed. In addition, the smoke outlet connecting pipe 13 is provided with a smoke temperature controller, which is used to detect the temperature of the discharged flue gas, and when the temperature of the discharged flue gas is too high, it proves that the shell 10 is abnormal, such as insufficient water level, etc. The outlet water connecting pipe 12 is provided with a second water temperature controller, which is used to detect whether the water temperature of the outlet hot water meets the requirements, so as to control the gas supply amount of the air inlet device 20 and increase the heating power.

[0035] The air inlet device 20 is arranged on the top of the shell 10 and is used to input the combustible gas, as shown in Figure 1 The air inlet device 20 includes a mounting flange for mounting on the shell 10, a connecting pipe, a fan, a Venturi and a gas proportional valve, and its principle is as follows: start the fan to suck in air, at the same time the gas proportional valve opens to input the gas and air into the Venturi for sufficient mixing, then through the connecting pipe, the mixed combustible gas is input into the combustion chamber 30 for ignition and combustion to generate high-temperature flue gas. The volumetric gas water heater of the present application adopts a conventional air inlet device 20, and the specific structure of each part will not be described here.

[0036] As Figure 2 And Figure 3 The combustion chamber 30 is arranged in the water storage cavity, and a combustion cylinder 31 is arranged on the top of the combustion chamber 30 and connected with the air inlet device 20 to input mixed gas into the combustion cylinder 31 to ignite combustion, wherein the ignition electrode 16 and the ion probe 17 are arranged close to the combustion cylinder 31. In an embodiment, the combustion chamber 30 is provided with a combustion chamber upper end cover and a combustion chamber lower end cover, both of which are arranged in an elliptical shape to buffer the high-temperature flue gas and improve the pressure-bearing capacity of the combustion chamber 30. In general, the inner and outer walls of the combustion chamber 30 are coated with a high-temperature-resistant material to improve its high-temperature resistance. The high-temperature-resistant material is a coating commonly used for inner liner temperature resistance on the market, which will not be described here. In other embodiments, a heat insulation sealing plate 21 is arranged at the connection between the air inlet device 20 and the combustion chamber 30. The heat insulation sealing plate 21 is but not limited to an aluminum silicate plate. Through the action of the aluminum silicate plate, the heat transfer efficiency between the combustion chamber 30 and the top of the air inlet device 20 and the outer shell 10 is reduced to avoid heat loss. The combustion cylinder 31 is a combustion cylinder 31 sold on the market, such as a Carter combustion cylinder 31, which will not be described here.

[0037] The heat exchange coil set 40 is arranged at the bottom of the combustion chamber 30. The heat exchange coil set 40 is formed by a plurality of heat exchange pipes spirally arranged from top to bottom. The heat exchange pipes include a first buffer pipe 41, a second buffer pipe 42, a spiral pipe 43 and an output pipe 44 connected in sequence. The first buffer pipe 41 is connected with the combustion chamber 30 and arranged vertically (relative to the flow direction of the flue gas) to facilitate the flue gas to be led out of the combustion chamber 30 to form a first buffer section. The second buffer pipe 42 is bent from one end of the first buffer pipe 41 to the direction of rotation of the spiral pipe 43. The angle formed by the second buffer pipe 42 and the first buffer pipe 41 is greater than the angle formed by the spiral pipe 43 and the first buffer pipe 41. That is, when the flue gas flows from the first buffer pipe 41 into the second buffer pipe 42, the angle between the second buffer pipe 42 and the first buffer pipe 41 is relatively gentle, and no vertical or relatively bent angle is formed, so that the flue gas flows out smoothly and smoothly, without much resistance. Therefore, through the action of the first buffer pipe 41 and the second buffer pipe 42, the space required for the flue gas to flow is increased, and the flue gas gently passes into the spiral pipe 43 to exchange heat with water to increase the temperature of the water. The output pipe 44 is arranged through the bottom of the outer shell 10 and connected with the flue gas outlet connecting pipe 13. In this embodiment, the output pipe 44 is arranged vertically to facilitate the external output of the flue gas. The output pipe 44 is arranged through the bottom of the outer shell 10 and connected with the smoke cylinder seat 14 to be connected with the inner smoke discharge channel and the outer smoke discharge channel, and then the flue gas is transported into the flue gas outlet connecting pipe 13 for external output. The heat exchange coil set 40, the smoke cylinder seat 14 and the flue gas outlet connecting pipe 13 form a flue gas absorption, utilization and discharge system.

[0038] In the embodiment, the angle between the second buffer tube 42 and the first buffer tube 41 is obtuse, and the angle between the spiral tube 43 and the first buffer tube 41 is obtuse. The angle between the second buffer tube 42 and the first buffer tube 41 is 145°-160°, and the angle between the spiral tube 43 and the first buffer tube 41 is 100°-130°. Preferably, the angle between the second buffer tube 42 and the first buffer tube 41 is 150°-160°, and the angle between the spiral tube 43 and the first buffer tube 41 is 110°-120°.

[0039] In other embodiments, the spiral lengths of the spiral tubes 43 are the same, and the spiral tubes 43 are spirally formed in the same downward direction to form a structure of stacking up and down, and the spiral tubes 43 have a spiral gap therebetween. Understandably, the heat exchange coil group 40 includes a plurality of heat exchange tubes, and the heat exchange tubes are uniformly distributed and arranged on the combustion chamber 30 (i.e., the first buffer tube 41), such as being arranged along a same circle at the bottom of the combustion chamber 30, and then spirally formed in the same direction. Because the spiral lengths are the same and the angles are the same, the trajectories are similar, so that the spiral tubes 43 are stacked up and down, and at the same time, the spiral tubes 43 have a spiral gap therebetween, i.e., a spring-like structure, so as to buffer the water flow and flue gas. The interval is designed according to the specific model, which is not described here.

[0040] In the embodiment, the number of the heat exchange coil groups 40 is three, and the heat exchange coil groups 40 are uniformly distributed from inside to outside, and the heat exchange coil groups 40 have a flow gap therebetween to uniformly distribute the flue gas in the combustion chamber 30. In an embodiment, the outer diameter of the innermost heat exchange coil group 40 is smaller than the outer diameter of the combustion chamber 30, and the outer diameter of the middle heat exchange coil group 40 is greater than the outer diameter of the combustion chamber 30, so as to improve the heat exchange efficiency of the internal coil and water. The number of the heat exchange coil groups 40 can be two, four, five, six, etc. in addition to the above limitation, which is designed according to the model and heat exchange efficiency of the water heater, which is not described here.

[0041] In other embodiments, the spiral number of the spiral tube 43 is two, the sum of the lengths of the first buffer tube 41 and the second buffer tube 42 is 1 / 4-1 / 3 of the length of one circle of the spiral tube 43, and the length of the first buffer tube 41 is 1 / 3-1 / 2 of the length of the second buffer tube 42.

[0042] The control system is used for controlling the whole device, and is electrically connected with the first water temperature controller, the water level electrode, the ignition electrode 16, the ion probe 17, the water pressure relief valve 18, the flue gas temperature controller, the second water temperature controller, the fan, the gas proportional valve, etc. to control the start and stop of the device after receiving the signals.

[0043] The principle of the volumetric gas water heater is that the water density decreases with the increase of temperature, the higher the water temperature, the upward flow of hot water, so that the water in the water storage cavity is higher, the water temperature is higher, to ensure that the output water is hot, the flue gas flows downward, and the high-temperature heat is continuously transferred from the top to the bottom of the water in the water storage cavity, so that the upper water is in a heated state, and the lower water is in a preheated state, so as to continuously and repeatedly utilize the heat of the flue gas, thereby improving the thermal efficiency of the water heater.

[0044] The volumetric gas water heater improves the heat exchange coil group 40, and the heat exchange coil group 40 is combined with the first buffer pipe 41, the second buffer pipe 42, the spiral pipe 43 and the output pipe 44, when the flue gas is sprayed, a better multi-stage buffering effect is formed, the flue gas is continuously input into the spiral pipe 43, and the water in the water storage cavity is heat exchanged, and then output, so that the flue gas can flow in the spiral pipe 43, and the phenomenon of insufficient combustion caused by backflow into the combustion chamber 30 is avoided, and better heat exchange effect between the pipe wall can be achieved, thereby further improving the thermal efficiency of the water heater.

[0045] The technical features of the above-mentioned embodiments can be combined arbitrarily, in order to make the description simple, not all possible combinations of the technical features in the above-mentioned embodiments are described, however, as long as the combination of the technical features does not exist contradictory, it should be considered that it is within the scope of the present application.

[0046] The above-mentioned embodiments only express several embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A volumetric gas water heater characterised in that, The utility model provides a kind of water heater, comprising: A shell with a water storage cavity, the shell is provided with water inlet pipe, water outlet pipe and flue gas outlet pipe; The water inlet pipe, water outlet pipe are communicated with the water storage cavity, the water inlet pipe, flue gas outlet pipe are arranged at the lower end of the shell, and the water outlet pipe is arranged at the upper end of the shell; An air inlet device is installed at the top of the shell for inputting combustible gas; A combustion chamber is arranged in the water storage cavity, and a combustion cylinder is installed at the top of the combustion chamber, which is communicated with the air inlet device;And At least one heat exchange coil group is installed at the bottom of the combustion chamber, and the heat exchange coil group is formed by a plurality of heat exchange pipes spirally arranged from top to bottom, the heat exchange pipes include a first buffer pipe, a second buffer pipe, a spiral pipe and an output pipe connected in sequence, the first buffer pipe is communicated with the combustion chamber and arranged vertically, the second buffer pipe is bent from one end of the first buffer pipe to the spiral pipe in the direction of rotation, and the angle formed by the second buffer pipe and the first buffer pipe is greater than the angle formed by the spiral pipe and the first buffer pipe;The output pipe is arranged in the bottom of the shell and communicated with the flue gas outlet pipe.

2. The volumetric gas water heater according to claim 1, wherein The angle formed by the second buffer pipe and the first buffer pipe is obtuse, and the angle formed by the spiral pipe and the first buffer pipe is obtuse.

3. A positive displacement gas water heater as claimed in claim 2 wherein, The angle formed by the second buffer pipe and the first buffer pipe is 145°-160°, and the angle formed by the spiral pipe and the first buffer pipe is 100°-130°.

4. The volumetric gas water heater according to claim 1, wherein The spiral length of each spiral pipe is the same and spirally arranged from top to bottom to form a stacked structure, and there is a spiral gap between each spiral pipe.

5. The positive displacement gas water heater of claim 1, wherein, The number of heat exchange coil groups is three, each heat exchange coil group is uniformly distributed from inside to outside, and there is a flow gap between each heat exchange coil group.

6. A positive displacement gas water heater as claimed in claim 5 wherein, The outer diameter of the innermost heat exchange coil group is smaller than the outer diameter of the combustion chamber, and the outer diameter of the middle heat exchange coil group is larger than the outer diameter of the combustion chamber.

7. The positive displacement gas water heater of claim 1, wherein, The combustion chamber is provided with a combustion chamber upper head and a combustion chamber lower head, and the combustion chamber upper head and the combustion chamber lower head are elliptical.

8. The positive displacement gas water heater of claim 1, wherein, The lower end of the shell is provided with a smoke box cylinder seat, the smoke box cylinder seat includes a seat body, a heat insulation plate and a smoke blocking ring, the smoke blocking ring is arranged on the heat insulation plate and divides the upper end of the seat body into an inner smoke discharge channel and an outer smoke discharge channel, the smoke blocking ring is provided with a smoke discharge opening, and the smoke discharge opening is oppositely arranged with the flue gas outlet pipe.

9. The positive displacement gas water heater of claim 1, wherein, The shell is provided with a shell upper head and a shell lower head, and the shell upper head and the shell lower head are elliptical.

10. The positive displacement gas water heater of claim 1, wherein, A heat insulation sealing plate is arranged at the connection between the air inlet device and the combustion chamber, and the heat insulation sealing plate is an aluminum silicate plate.

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