Proposal for Solar and Air Energy Hot Water System at Nanning Leyang City Maintenance Center in China 
1、 Project Overview 
The Nanning Leyang City Care Center in China is committed to providing high-quality and comfortable living environments for the elderly, and hot water supply is a crucial part of it. To meet the daily hot water demand of the maintenance center and achieve energy-saving, environmentally friendly, efficient and stable supply goals, a hot water supply solution combining solar energy and air energy is adopted. This plan uses 296 square meter Megaray brand solar collectors, paired with two 10 horsepower air source water heaters and two 7-ton insulated water tanks. 
2、 Design Basis 
1. The actual hot water usage demand of the maintenance center, including the estimated amount of hot water used for daily washing, cleaning, catering, and other aspects of the elderly and staff. 
2. Local climate conditions, such as sunshine duration, average temperature, humidity, etc., to facilitate the rational design of the ratio and operation mode of solar collectors and air source water heaters. 
3. Relevant national and industry standards, such as GB 50015-2019 "Design Standards for Building Water Supply and Drainage" and GB/T 20095-2017 "Energy Efficiency Limits and Grades for Household Solar Hot Water Systems". 

3、 Equipment selection 
1. Solar collector: Select Megaray brand flat panel solar collectors with a collection area of 296 square meters. This collector adopts advanced full plate welded heat absorbing core, matched with textured tempered glass and aluminum alloy frame, with high heat absorption and low heat loss characteristics. The film absorption rate is as high as 97%, which can effectively convert solar energy into heat energy and maintain good heat collection performance even in winter or weak light weather. 
2. Air source water heater: Two 10 horsepower air source water heaters are used, each with a heating capacity of 38kw. Air source water heaters use the reverse Carnot cycle principle to absorb heat from the air to heat water, which has the characteristics of high efficiency and energy saving. The heating performance coefficient is high, and it can operate stably at lower ambient temperatures. As a supplementary heating device for solar energy, it ensures that hot water demand can be met even when solar energy is insufficient. 
3. Insulated water tank: equipped with 2 7-ton insulated water tanks, with a total storage capacity of 14 tons. The water tank adopts high-quality insulation materials, which can effectively reduce heat loss, maintain the temperature of hot water, ensure the stability and continuity of hot water supply, and meet the hot water usage needs of the maintenance center at different times. 
4、 System working principle 
1. Solar priority mode: During the day when there is sufficient sunlight, the solar collector converts the absorbed solar energy into heat energy, heats the circulating water, and stores the hot water in the insulated water tank. When the water temperature in the water tank reaches the set upper limit, the solar circulation pump stops working. 
2. Air assisted heating mode: When there is insufficient solar energy, the water temperature in the water tank has not reached the set temperature, or the water consumption is large, causing the water temperature in the water tank to drop, the air source water heater starts up, absorbs heat from the air, and heats the water in the water tank until it reaches the set temperature. 
3. Constant temperature water supply mode: The hot water in the insulated water tank is transported to various water consumption points through the water supply pipeline. The water level and temperature of the water tank are monitored in real time by the control system, and the operation of the solar circulation pump and air source water heater is automatically adjusted to ensure 24-hour constant temperature and pressure water supply. 
5、 Installation and Debugging 
1. Installation: According to the layout of the maintenance center building, plan the installation position of the solar collector reasonably to ensure that it fully receives sunlight; Air source water heaters should be installed in areas with good ventilation and easy maintenance; The insulated water tank is installed on a stable foundation and measures such as insulation and leakage prevention are taken. The pipeline connection should comply with relevant specifications to ensure smooth circulation of hot water. 
2. Debugging: After the system installation is completed, conduct comprehensive debugging. Check the heat collection effect of the solar collector, the heating performance of the air source water heater, the insulation performance of the water tank, and the operational stability of the entire system. Optimize and adjust the operating parameters of each equipment to ensure the normal operation of the system. 
6、 Operation and maintenance 
1. Daily maintenance: Regularly check whether there is dust or debris blocking the surface of the solar collector, and keep the collection surface clean; Check whether the compressor, fan and other components of the air source water heater are operating normally, and whether there are any abnormal noises or vibrations; Check if there is any water leakage in the water tank and pipelines, and if all valve switches are flexible. 
2. Regular maintenance: Conduct a comprehensive inspection of the solar collector once a year, including the wear and tear of components such as vacuum tubes and seals; Perform in-depth maintenance on the air source water heater every six months, clean the condenser, evaporator and other components, and check if the refrigerant is sufficient; Regularly clean and disinfect the water tank to ensure water quality and hygiene. 

7、 Benefit analysis 
1. Energy saving benefits: Both solar energy and air energy are clean energy sources. Solar collectors use free solar energy, while air energy water heaters have high energy efficiency. Compared with traditional electric or gas heating methods, they can significantly reduce energy consumption and operating costs. 
2. Environmental benefits: Reducing the use of fossil fuels, lowering emissions of pollutants such as carbon dioxide and sulfur dioxide, which is beneficial for environmental protection and in line with the concept of sustainable development. 
3. Economic benefits: Although the initial equipment investment is relatively high, over long-term operation, the cost reduction brought by energy conservation is significant, and the equipment has a long service life and low maintenance costs, with good economic benefits.