Thermal performance, the higher the average efficiency ", the better, the average heat loss coefficient as low as possible.

    The two key components of domestic solar water heater is the all-glass vacuum tube solar collectors, referred to as the vacuum tube, vacuum quality directly affects the performance of domestic solar water heaters. Purchase should carefully observe the coating on the glass vacuum tube, the coating layer is called the solar powered water heater selective absorbing coating, the coating color will be different due to different production process of the manufacturers, but are generally black, dark blue or dark gray, good quality coating color uniformity, film no scratches, no peeling or shedding phenomenon, no stones or nodules on the phenomenon of glass, the glass support within the support placed upright, not loose.

    When you purchase should also be noted that the vacuum tube between the tube spacing, generally two center distance of about 70mm is appropriate.

    4 stent design of domestic solar water heaters should be reasonable and should have sufficient strength and rigidity to ensure adequate load bearing capacity. Daily wind regions, especially coastal areas, buy home solar water heater should also note that this product is designed for wind resistance.

    (5) currently on the market, variety of reflectors in the form of domestic solar water heater, flat reflectors, reflective surface plate, embossed aluminum reflector design of the product can take full advantage of the vacuum tube, look out the heat-absorbing surface, vacuum the greatest degree of light.
   
    Should also be considered in the purchase of the resident population in the home, to determine the size of the purchase of water capacity of domestic solar water heaters. General standard of 40 liters of water per person is appropriate. In addition, many products nominal capacity of water is calculated from the sum by calculating the capacity of each tube and the water tank capacity, but in fact the water below the water heater outlet and the vacuum tube can not be let out to use, the user can really water use only the amount of water between the inlet and overflow, so the purchase should ask the vendors, their nominal capacity of water is the water capacity of all of the water capacity is actually available, The difference between the two.

    . Enough to buy a home solar water heaters need to configure the electrical chinese solar water heater device should be selected with the design of electrical safety products.

    8. Purchase other accessories such as automatic water device, temperature and water level indicator, solenoid valve, the choice of these devices should be careful, some features may seem advanced, but too many component parts, high reliability, time long vulnerable, choose, be sure to ask when life and warranty period.

    . To buy a good home solar water heater during the installation process should be noted that the bracket is firmly installed on whether all screws and fittings tight, up and down the water pipe installation location is reasonable, the water heater itself is reinforced measures. In addition, in the Sheung Shui piping must want to install non-return device to prevent the backflow of hot water to flow backward into the cold water pipe.

    10 domestic solar water heaters after-sales service is also very important. The best choice for the well-known brand products and good after-sales service dealers. Because home solar water heaters, consumer durables, and is usually installed on the roof, once a fault, the user is difficult to solve their own, so after-sales service must be guaranteed. At present, the machine on the market free warranty period is generally 3 to 5 years.

    11 domestic solar water heater is installed outdoors, prolonged use of the vacuum tube will be dust or impurity contamination, resulting in heat absorption efficiency decreased. So the water heater vacuum tube should be cleaned regularly, especially in the winter snowy areas, snow need more timely liquidation. If the impact of housing design, and can not be cleaned should ask the dealer after-sales service contains regularly cleaning a.