Intelligent preheating and waste heat recovery energy-saving water supply control device and method

Abstract

The invention provides an intelligent preheating and waste heat recovery energy-saving water supply control device and method, and relates to the technical field, and the intelligent preheating and waste heat recovery energy-saving water supply control device comprises a water consumption habit analysis module, a dynamic preheating circulation module, a multiple waste heat recovery module, an intelligent anti-freezing module and a control system. The invention provides an intelligent preheating and waste heat recovery energy-saving water supply control device and method. Through dual-mode control of water consumption habit prediction and dynamic preheating, 7-day water consumption data (time, duration and frequency) are collected through a flow sensor, a high-frequency water consumption time period is generated through an algorithm, and preheating is started 15 minutes ahead of time; in a non-prediction period, the circulating pump is triggered through the temperature sensor to operate for a short time, instant heating is achieved, and cold water discharge is thoroughly eliminated; except that a preheating heat exchanger utilizes the waste heat of the discharged smoke, a newly added smoke deep waste heat recoverer conducts secondary heat exchange on the discharged smoke, waste heat is further extracted, the temperature of circulating water is further increased, the waste heat utilization rate is increased, and energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to the field of gas water heater technology, and in particular to an intelligent preheating and waste heat recovery energy-saving water supply control device and method. Background Technology

[0002] When gas water heaters are used in homes and commercial establishments, there is always a water pipe of varying length between the water heater and the water point (such as bathroom shower, kitchen faucet, hotel room shower head, restaurant kitchen faucet, etc.). When not in use, this pipe will continuously retain room temperature cold water (usually 20-25℃ in summer and as low as 5-10℃ in winter). Every time a water heater is turned on, the user must first completely drain the cold water in this section of the pipe before the hot water can reach the point of use. In a home setting, if the bathroom is far from the water heater (such as the bathroom on the second floor of a duplex), the pipe length can reach 10-15 meters, and the amount of cold water drained at one time is about 1.5-3L. A family of three can waste 10-15L of cold water per day due to washing, cooking and other needs. In a commercial setting, the pipe network on each floor of a hotel covers multiple guest rooms, and the length of a single main pipe often exceeds 20 meters. Every time a guest turns on the shower, 2-4L of cold water needs to be drained to obtain hot water. If 50 guest rooms in a hotel use hot water every day, the amount of cold water wasted per day exceeds 100L.

[0003] Besides wasting water resources, the cold water discharge process also significantly prolongs the waiting time for users, resulting in a poor user experience, especially in winter. In winter, the ambient temperature is low, and the temperature of the cold water in the pipes is only 5-8℃. After turning on the shower, users need to wait 30-60 seconds in the cold environment before they can access hot water. This not only easily leads to health problems such as colds, but also reduces user satisfaction with hot water use. Elderly people and children in the family are more sensitive to the cold, and their discomfort during the waiting process is more obvious. In commercial places such as hotels and apartments, guests have higher requirements for the immediacy of hot water supply. Excessive waiting time can easily lead to customer complaints and affect the reputation of the venue. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes an intelligent preheating and waste heat recovery energy-saving water supply control device and method.

[0005] The intelligent preheating and waste heat recovery energy-saving water supply control device proposed in this invention includes a water usage habit analysis module, a dynamic preheating circulation module, a multiple waste heat recovery module, an intelligent antifreeze module, and a control system. The water usage habit analysis module includes flow sensors installed on the pipes at each water point, and a habit analysis algorithm integrated into the control system. The dynamic preheating circulation module includes a micro circulation pump, a preheating heat exchanger, and a pipe temperature sensor; one end of the micro circulation pump is connected to the outlet pipe of the gas water heater, and the other end is connected to the end of the water point pipe; the preheating heat exchanger is nested on the outside of the exhaust pipe of the gas water heater; the pipe temperature sensor monitors the water temperature inside the water supply pipe in real time. The multi-stage waste heat recovery module includes a preheating heat exchanger, a heat-conducting pipe inside the insulation layer on the outside of the water tank, and a deep waste heat recovery device for flue gas installed at the end of the flue gas pipe. The deep waste heat recovery device for flue gas has a finned tube structure with a serpentine heat exchange tube inside. One end of the serpentine heat exchange tube is connected to the outlet of the preheating heat exchanger, and the other end is connected to the return water pipe. One end of the heat-conducting pipe is connected to the outlet of the micro-circulation pump, and the other end is connected to the inlet of the water tank. The intelligent antifreeze module includes an electric heating tape and an ambient temperature sensor. The electric heating tape is wrapped around the outdoor exposed section of the water pipeline and the area of ​​the pipeline with a low temperature. The ambient temperature sensor is installed outdoors. The control system is electrically connected to the flow sensor, pipe temperature sensor, micro circulation pump, gas water heater main controller, electric heating tape, and ambient temperature sensor, respectively.

[0006] Preferably, the habit analysis algorithm generates a user's "high-frequency water usage period" by collecting data on the time, duration, and frequency of each water usage session over seven consecutive days, and synchronizes this period to the dynamic preheating cycle module.

[0007] Preferably, 15 minutes before the user's "high-frequency water usage period", the control system starts the micro circulation pump to pump the cold water in the pipeline to the preheating heat exchanger and the flue gas deep waste heat recovery unit, heat it to 30-35°C and then return it to the pipeline until the pipeline temperature sensor detects that the water temperature is stable at 32°C, at which point the micro circulation pump automatically stops.

[0008] Preferably, if a user uses water temporarily outside of a predicted period, the pipe temperature sensor will detect the cold water flow signal and immediately trigger the micro-circulation pump to start briefly for 10-20 seconds to quickly push the preheated water to the point of use.

[0009] Preferably, when the water point valve is opened, the flow sensor sends a "water usage signal", and the control system first determines whether the water temperature in the pipeline is ≥30℃: if it meets the standard, the main heating of the water heater is turned on directly; if it does not meet the standard, the micro circulation pump is immediately started to push preheated water, and the main heating of the water heater is started 3 seconds in advance.

[0010] Preferably, after the water usage ends, the micro circulation pump automatically runs for 5 seconds to return the residual hot water in the pipe to the water tank.

[0011] Preferably, when the ambient temperature sensor detects that the ambient temperature is below 5°C, the control system activates the electric heating tape to heat the pipeline; when the ambient temperature rises to above 10°C, the electric heating tape stops working.

[0012] The intelligent preheating and waste heat recovery energy-saving water supply control method includes the following steps: Habit learning phase: When users use the water heater normally, the flow sensor records the time and duration of each water usage, and the control system generates "high-frequency water usage periods" through algorithms; Preheating circulation stage: 15 minutes before the high-frequency water usage period, the control system starts the micro circulation pump to pump the cold water in the pipeline to the preheating heat exchanger and the flue gas deep waste heat recovery unit, and heats it to 32°C. After the pipeline temperature sensor detects that the water temperature has reached the standard, the micro circulation pump stops. Temporary water use phase: If a user turns on the tap during an unpredictable period, the flow sensor sends a signal, and the control system immediately starts the micro circulation pump to run for 15 seconds, pushing preheated water to the point of use, while simultaneously starting the main heating of the water heater. Waste heat recovery stage: When the micro circulation pump is running, the heat pipe transfers part of the heat of the preheated water to the cold water in the water tank; after the water is used, the micro circulation pump runs in reverse for 5 seconds to return the residual hot water in the pipe to the water tank. Anti-freeze protection phase: When the ambient temperature sensor detects that the ambient temperature is below 5°C, the control system activates the electric heating tape to heat the pipeline; when the ambient temperature rises to above 10°C, the electric heating tape stops working.

[0013] Preferably, during the habit learning phase, the user's "high-frequency water usage periods" are generated through data learning over seven consecutive days.

[0014] Preferably, during the waste heat recovery stage, the water inlet temperature of the water tank is increased by 5-8°C.

[0015] The intelligent preheating and waste heat recovery energy-saving water supply control device and method proposed in this invention have the following beneficial effects: Through dual-mode control of "water usage habit prediction + dynamic preheating": by collecting 7 days of water usage data (time, duration, frequency) through a flow sensor, the algorithm generates high-frequency water usage periods and starts preheating 15 minutes in advance; during non-predicted periods, the circulating pump is triggered by a temperature sensor to run for a short time to achieve "instant hot water" and completely eliminate cold water discharge.

[0016] Deep recovery of flue gas waste heat: In addition to the preheating heat exchanger utilizing flue gas waste heat, the newly added deep flue gas waste heat recovery unit performs secondary heat exchange on the flue gas, further extracting waste heat, thereby further increasing the circulating water temperature, improving waste heat utilization rate, and reducing energy consumption.

[0017] Intelligent anti-freeze protection: By combining ambient temperature sensors and electric heating tape, the pipeline is heated in cold weather to prevent it from freezing and cracking, thus improving the reliability of the device in low-temperature environments.

[0018] Through low-cost modular adaptation design: the core components (micro circulation pump, sensor, electric heating tape, etc.) have low cost and adopt a modular structure, which can be directly installed on the existing water heater pipes without replacing the whole unit, and is compatible with more than 90% of household gas water heater models.

[0019] Through intelligent linkage control logic: when water is used, the water temperature in the pipes is judged first. If the temperature meets the standard, the main heater is started directly. If the temperature does not meet the standard, the circulation pump is linked to push hot water and the main heater is started 3 seconds in advance. After water is used, the circulation pump runs in reverse for 5 seconds to recover the residual hot water in the pipes and avoid heat waste. At the same time, the antifreeze protection is intelligently activated according to the ambient temperature. Attached Figure Description

[0020] Figure 1 This is a flowchart of the intelligent preheating and waste heat recovery energy-saving water supply control method proposed in this invention.

[0021] In the diagram: 1. Miniature circulating pump; 2. Exhaust pipe; 3. Preheating heat exchanger; 4. Water tank; 5. Waste heat recovery heat transfer pipe; 6. Pipe temperature sensor; 7. Flow sensor; 8. Water usage point; 9. Control system. Detailed Implementation

[0022] Reference Figure 1 This invention proposes an intelligent preheating and waste heat recovery energy-saving water supply control device, which consists of a water usage habit analysis module, a dynamic preheating circulation module, a multiple waste heat recovery module, an intelligent antifreeze module, and a control system. The specific structure and working principle are as follows: Water usage habit analysis module: This includes flow sensors 7 installed on the pipes at each water point 8, and a habit analysis algorithm integrated into the control system 9. Flow sensors 7 collect data on the time, duration, and frequency of user water usage in real time. The habit analysis algorithm learns from data over 7 consecutive days and uses a "weighted average method" to generate high-frequency water usage periods (time weight 0.6, frequency weight 0.4). If there is no water usage data for a certain day (e.g., the user is away), the average data of the previous 3 days is used to fill in the gaps, avoiding the loss of high-frequency periods. The generated high-frequency periods are automatically updated every 7 days to adapt to changes in user water usage habits, generating the user's "high-frequency water usage periods" (e.g., 6:50-7:20 am, 7:50-8:30 pm), and synchronizing these periods to the dynamic preheating cycle module.

[0023] The dynamic preheating circulation module consists of a miniature circulation pump 1 (model RS-15 / 3), a preheating heat exchanger 3, and a pipe temperature sensor 6. The miniature circulation pump 1 is a silent pump with a flow rate of 8-10 L / min and a head of 3-5 m. The preheating heat exchanger 3 has a spiral tube inner diameter of Φ15 mm (flow area 2.25 cm²). 2 The inner diameter of the serpentine tube in the deep waste heat recovery unit is Φ12mm (flow area 1.13cm²). 2 The circulating water flow rate is kept stable at 0.8-1.0 m / s by changing the pipe diameter from "preheating heat exchanger outlet to flue gas deep waste heat recovery device inlet" (Φ15→Φ12). This ensures sufficient heat exchange while avoiding overload of the circulating pump. One end of the micro circulating pump 1 is connected to the outlet pipe of the gas water heater, and the other end is connected to the end of the pipe at water point 8. The preheating heat exchanger 3 is nested outside the exhaust pipe 2 of the gas water heater to heat the circulating water using the waste heat from the exhaust. The pipe temperature sensor 6 monitors the water temperature in the water supply pipe in real time (the pipe temperature sensor 6 is installed near the end of the pipe at the water point, 10-15 cm away from the valve). Fifteen minutes before the user's "high-frequency water usage period," the control system 9 starts the micro-circulation pump 1, which pumps the cold water in the pipeline to the preheating heat exchanger 3. The water is then heated to 30-35°C using the waste heat from the flue gas and returned to the pipeline. The micro-circulation pump 1 automatically stops when the pipeline temperature sensor 6 detects that the water temperature has stabilized at 32°C. If the user uses water temporarily outside of the predicted period, the pipeline temperature sensor 6 detects the cold water flow signal and immediately triggers the micro-circulation pump 1 to start briefly (10-20 seconds), quickly pushing the preheated water to the water usage point 8 to eliminate the cold water discharge process.

[0024] Multiple waste heat recovery modules Waste heat recovery from flue gas: The preheating heat exchanger 3 is made of stainless steel and is spirally wound around the outside of the flue gas pipe 2 of the gas water heater (winding length 15-20cm), using the waste heat from the flue gas at 150-200℃ to heat the circulating water.

[0025] Waste heat recovery in water tank 4: A 50mm thick rock wool insulation layer is wrapped around the outside of the gas water heater water tank 4, and a Φ10mm copper heat-conducting pipe is embedded in the insulation layer. One end of the heat-conducting pipe is connected to the outlet pipe of the circulation pump through a DN10 branch pipe (leading out from the Φ15 main pipe of the micro circulation pump 1 outlet pipe, with a DN10 ball valve to control the flow rate) and the other end is connected to the inlet of water tank 4 through a DN10 straight connector. The angle between the branch pipe and the main pipe is 30° to ensure that the water flow output by the circulation pump first satisfies the "main circulation of the preheating heat exchanger" and then is diverted to the heat-conducting pipe through the branch pipe to avoid insufficient main preheating flow. When the micro circulation pump 1 delivers preheated water, some of the heat is transferred to the cold water in water tank 4 through the heat-conducting pipe, further increasing the inlet water temperature and reducing the energy consumption of the main heating device of the gas water heater.

[0026] Deep waste heat recovery unit for flue gas (not shown in the figure): A deep waste heat recovery unit for flue gas is installed at the end of the flue gas pipe 2. The unit is a finned tube structure made of 304 stainless steel with a fin thickness of 0.8-1.2mm, a fin spacing of 8-12mm, and a fin height of 15-20mm. The internal serpentine heat exchange tube is a Φ12-15mm copper tube with 4-6 turns and a tube length of 1.2-1.5m. One end of the serpentine heat exchange tube is connected to the outlet of the preheating heat exchanger 3 through a DN15 straight connector, and the other end is connected to the return water pipe (a Φ15 PPR pipe connecting the outlet of the deep waste heat recovery unit to the main pipe of the water point) through a DN15 one-way valve (to prevent backflow of return water). The bottom of the unit is equipped with a Φ8mm condensate drain outlet, which is connected to an external silicone tube to the indoor floor drain to prevent condensate from corroding the flue gas pipe. The flue gas discharged from the flue pipe 2 (temperature 80-120℃, after initial cooling by the preheating heat exchanger) undergoes secondary heat exchange with the circulating water (temperature 25-30℃) in the serpentine tube when it passes through the recovery unit, which raises the temperature of the circulating water by another 3-5℃. The final exhaust temperature drops to 50-60℃, improving the waste heat utilization rate.

[0027] Intelligent antifreeze module: For exposed outdoor sections of water pipelines (if any) and areas with low pipe temperatures (such as pipelines near exterior walls), wrap a self-regulating heating cable (IP67 insulation class, temperature resistance -40℃~120℃) with a power of 15-20W / m. The heating cable is fixed to the pipeline using high-temperature resistant clips (15-20cm spacing), and the outer layer is wrapped with a 20mm thick glass wool insulation layer. The heating cable connects to the control system via a 2.5mm... 2 The connection uses copper core wires, which are protected by PVC conduit. The ambient temperature sensor 10 (model: DS18B20, accuracy ±0.5℃) is installed outdoors in a well-ventilated, rain-sheltered location (1.5m above the ground, away from heat sources) and connected to the control system 9 via wires. When the ambient temperature sensor 10 detects a temperature below 5℃, the control system 9 activates the electric heating tape to maintain the pipe's outer wall temperature at 8-10℃. When the ambient temperature rises above 10℃, the electric heating tape stops working to prevent the pipe from freezing and cracking.

[0028] Intelligent control logic: The control system 9 (core chip: STM32F103) is electrically connected to the flow sensor 7 (model: YF-S201), the pipe temperature sensor 6 (model: NTC10K), the ambient temperature sensor 10, the micro circulation pump 1 (model: RS-15 / 3), the gas water heater main controller, and the electric heating tape. The control system communicates with the water heater main controller via an RS485 interface. When the valve at water point 8 is opened, the flow sensor 7 sends a "water usage signal," and the control system 9 prioritizes reading the data from the pipe temperature sensor 6. When the water temperature is ≥30℃, a "start command" is sent directly to the main controller of the water heater via RS485. If the water temperature is <30℃, the micro circulation pump 1 is immediately started to push preheated water, and a "start command 3 seconds in advance" is sent via the interface to ensure that the main heater has started when the hot water arrives. After water use, the control system 9 switches the circulation pump 1 to reverse mode (by switching the motor phase via a relay), closes the one-way valve at the outlet of the flue gas deep waste heat recovery unit, and opens the hot water return port on the top of the water tank 4 to allow the residual hot water in the pipes to return to the water tank 4. The circulation pump stops after 5 seconds to avoid heat waste. When the ambient temperature is below 5℃, the electric heating tape is activated for freeze protection.

[0029] The flow sensor 7 is installed in series at the inlet pipe of the bathroom shower and kitchen faucet (5-10cm from the valve), and connected to the control system 9 via wires; the micro circulation pump 1 is fixed below the gas water heater, with its inlet connected to the water heater outlet pipe via a T-connector, and its outlet connected to the end of the pipe at the furthest water point 8; the preheating heat exchanger 3 is made of stainless steel and is spirally wound around the outside of the gas water heater exhaust pipe 2 (winding length 15-20cm), with its two ends connected to the outlet of the micro circulation pump 1 and the inlet of the serpentine heat exchange tube of the flue gas deep waste heat recovery device, respectively; the flue gas deep waste heat recovery device is installed at the end of the exhaust pipe 2, and the outlet of the serpentine heat exchange tube is connected to the return pipe of the pipeline; a copper heat-conducting pipe is embedded inside the insulation layer of the water tank 4, with one end connected to the outlet pipe of the micro circulation pump 1 and the other end connected to the inlet of the water tank 4; the electric heating tape is wrapped around the outdoor exposed section of the water supply pipeline and the area of ​​the pipeline with a low temperature, and the ambient temperature sensor is installed outdoors, both of which are connected to the control system 9 via wires to complete the overall assembly.

[0030] Specific workflow: Habit learning phase (days 1-7): Users use the water heater normally. Flow sensor 7 records the time and duration of each water usage. Control system 9 generates "high-frequency water usage periods" (such as 6:50-7:20 in the morning) through algorithms.

[0031] Preheating circulation stage: 15 minutes before the high-frequency water usage period, the control system 9 starts the micro circulation pump 1 to pump the cold water in the pipeline to the preheating heat exchanger 3, which uses the waste heat of the flue gas for initial heating, and then enters the flue gas deep waste heat recovery unit for secondary heating, so that the circulating water is heated to 32°C. After the pipeline temperature sensor 6 detects that the water temperature meets the standard, the micro circulation pump 1 stops.

[0032] Temporary water use phase: If a user turns on the tap during an unpredictable period (such as 12:00 noon), the flow sensor 7 sends a signal, and the control system 9 immediately starts the micro circulation pump 1 (runs for 15 seconds), pushing the preheated water heated by the preheating heat exchanger 3 and the flue gas deep waste heat recovery device to the water point 8. At the same time, the main heating of the water heater is activated to achieve "instant hot water".

[0033] Waste heat recovery stage: When the micro circulation pump 1 is running, the heat pipe transfers part of the heat of the preheated water to the cold water in the water tank 4, raising the inlet water temperature of the water tank 4 by 5-8℃ and reducing the main heating energy consumption; after the water is used, the micro circulation pump 1 runs in reverse for 5 seconds to return the residual hot water in the pipe to the water tank 4.

[0034] Anti-freeze protection stage: When the ambient temperature sensor detects that the ambient temperature is below 5℃, the control system 9 starts the electric heating tape to heat the pipeline; when the ambient temperature rises to above 10℃, the electric heating tape stops working.

[0035] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. Intelligent preheating and waste heat recovery energy-saving water supply control device, including water usage habit analysis module, dynamic preheating circulation module, multiple waste heat recovery module, intelligent antifreeze module and control system (9). The water usage habit analysis module includes flow sensors (7) installed on the pipes at each water usage point (8), and a habit analysis algorithm integrated into the control system (9); The dynamic preheating circulation module includes a micro circulation pump (1), a preheating heat exchanger (3), and a pipe temperature sensor (6); one end of the micro circulation pump (1) is connected to the outlet pipe of the gas water heater, and the other end is connected to the end of the pipe of the water point (8); the preheating heat exchanger (3) is nested outside the exhaust pipe (2) of the gas water heater; the pipe temperature sensor (6) monitors the water temperature in the water supply pipe in real time. The multi-stage waste heat recovery module includes a preheating heat exchanger (3), a heat-conducting pipe inside the insulation layer on the outside of the water tank (4), and a deep waste heat recovery device for flue gas installed at the end of the flue gas pipe (2); the deep waste heat recovery device for flue gas is a finned tube structure with a serpentine heat exchange tube inside, one end of the serpentine heat exchange tube is connected to the outlet of the preheating heat exchanger (3), and the other end is connected to the return water pipe of the pipeline; one end of the heat-conducting pipe is connected to the outlet of the micro circulation pump (1), and the other end is connected to the inlet of the water tank (4); The intelligent antifreeze module includes an electric heating tape and an ambient temperature sensor. The electric heating tape is wrapped around the outdoor exposed section of the water pipeline and the area of ​​the pipeline with a low temperature. The ambient temperature sensor is installed outdoors. The control system (9) is electrically connected to the flow sensor (7), the pipeline temperature sensor (6), the micro circulation pump (1), the gas water heater main controller, the electric heating tape, and the ambient temperature sensor, respectively.

2. The intelligent preheating and waste heat recovery energy-saving water supply control device according to claim 1, characterized in that, The habit analysis algorithm generates "high-frequency water usage periods" for users by collecting data on the time, duration, and frequency of each water usage session over seven consecutive days, and synchronizes these periods to the dynamic preheating cycle module.

3. The intelligent preheating and waste heat recovery energy-saving water supply control device according to claim 1, characterized in that, Fifteen minutes before the user's "high-frequency water usage period", the control system (9) starts the micro circulation pump (1) to pump the cold water in the pipeline to the preheating heat exchanger (3) and the flue gas deep waste heat recovery unit, heat it to 30-35°C and then return it to the pipeline until the pipeline temperature sensor (6) detects that the water temperature is stable at 32°C, and the micro circulation pump (1) automatically stops.

4. The intelligent preheating and waste heat recovery energy-saving water supply control device according to claim 1, characterized in that, If a user uses water temporarily outside of the predicted period, the pipe temperature sensor (6) will detect the cold water flow signal and immediately trigger the micro circulation pump (1) to start for 10-20 seconds to quickly push the preheated water to the point of use (8).

5. The intelligent preheating and waste heat recovery energy-saving water supply control device according to claim 1, characterized in that, When the valve of the water point (8) is opened, the flow sensor (7) sends a "water use signal". The control system (9) first determines whether the water temperature in the pipeline is ≥30℃: if it meets the standard, the main heating of the water heater is turned on directly; if it does not meet the standard, the micro circulation pump (1) is started immediately to push preheated water, and the main heating of the water heater is started 3 seconds in advance.

6. The intelligent preheating and waste heat recovery energy-saving water supply control device according to claim 1, characterized in that, When the water usage ends, the micro circulation pump (1) will run automatically for 5 seconds to return the residual hot water in the pipe to the water tank (4).

7. The intelligent preheating and waste heat recovery energy-saving water supply control device according to claim 1, characterized in that, When the ambient temperature sensor detects that the ambient temperature is below 5°C, the control system (9) starts the electric heating tape to heat the pipeline; when the ambient temperature rises to above 10°C, the electric heating tape stops working.

8. A smart preheating and waste heat recovery energy-saving water supply control method, employing the smart preheating and waste heat recovery energy-saving water supply control device and method as described in any one of claims 1-7, characterized in that, Includes the following steps: Habit learning stage: When the user uses the water heater normally, the flow sensor (7) records the time and duration of each water use, and the control system (9) generates "high-frequency water use periods" through the algorithm; Preheating circulation stage: 15 minutes before the high-frequency water use period, the control system (9) starts the micro circulation pump (1) to pump the cold water in the pipeline to the preheating heat exchanger (3) and the flue gas deep waste heat recovery device, heat it to 32°C, and after the pipeline temperature sensor (6) detects that the water temperature meets the standard, the micro circulation pump (1) stops. Temporary water use phase: If the user turns on the tap during an unpredictable period, the flow sensor (7) sends a signal, and the control system (9) immediately starts the micro circulation pump (1) to run for 15 seconds, pushing preheated water to the water point (8), and at the same time, the main heating of the water heater is started. Waste heat recovery stage: When the micro circulation pump (1) is running, the heat pipe transfers part of the heat of the preheated water to the cold water in the water tank (4); after the water is used, the micro circulation pump (1) runs in reverse for 5 seconds to return the residual hot water in the pipe to the water tank (4). Anti-freeze protection stage: When the ambient temperature sensor detects that the ambient temperature is below 5°C, the control system (9) starts the electric heating tape to heat the pipeline; when the ambient temperature rises to above 10°C, the electric heating tape stops working.

9. The intelligent preheating and waste heat recovery energy-saving water supply control method according to claim 8, characterized in that, During the habit learning phase, the system generates users' "high-frequency water usage periods" by learning from data over seven consecutive days.

10. The intelligent preheating and waste heat recovery energy-saving water supply control method according to claim 1, characterized in that, During the waste heat recovery stage, the inlet water temperature of the water tank (4) is increased by 5-8℃.

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