5 guides to buy solar water heater
Solar water heating is a very mature technology in today’s society, and is used widely across the world. Whether you’re an individual consumer or an import agency, there’re at least 5 aspects you should consider before deciding whose solar water heaters you want to buy. Here is a quick glance.
System pressure. You need to decide whether you need an unpressurized system or pressurized system.
Vacuum tube or flat plate collector. You need decide your solar collector to be vacuum tube or flat plate collector.
Solar water heater tank inner material: SUS304-2B or enamel coating
Solar water heater tank outer material: painted steel or stainless steel or aluminium
Back-up electric heating element.
1. System pressure. There are pressurized system and unpressurized system for your option. The unpressurized system means that solar water heater tank pressure is very low. This system must be installed at a high altitude so that hot water can flow down by gravity, while pressurized system is not restricted by installation position. It can be installed on the first floor, even your bathroom is on the second floor. That’s because pressurized system is operating under pressure. Tapwater pressure pushes hot water out from the storage tank for usage. So normally pressurized system is a better choice than unpressurized system in terms of ensuring good bath experience. On the other hand, pressurized system requires much more technology than unpressurized, such as thicker inner tank, heat pipe other than vacuum tube, so its price is also higher.
2. Vacuum tube or flat plate collector. This all depends on you. They are both excellent in thermal efficiency. Vacuum tube is widely used in China and flat plate collector is mainly used in Europe. But if you’re from somewhere water quality is not good, we advice you to choose vacuum tube. As the copper pipe in flat plate collector is very thin, the impurities of water may block the pipes, which will reduce the efficiency of the whole system.
3. Solar water heater tank inner material. Normally you will have two choices: SUS304-2B and enamel coating(glass-lined coating). Enamel coating is a better choice than SUS304-2B theoretically. It is usually coupled with a magnesium rod, which is also called sacrificed anode. Magnesium rod is very important for an enameled tank. That’s because if enamel coating has any defect, it is the magnesium rod been corroded first, rather than the tank itself. Actually very few company is doing well in the control of enameling process in China. So if you’re using an enamel coated tank, you need to replace the magnesium rod regularly(every 6 months). Or it is very likely your tank will be corroded. SUS304-2B is still the most widely used material in the solar water heating industry now.
4. Solar water heater tank outer material. The most common material used in the industry is painted steel as it is affordable and easy to be processed. It is almost applicable for all conditions, except the seaside areas. The air of the seaside area is very salty. Painted steel is very easy to be corroded. So if you live near the sea, buy solar water heater with stainless steel or aluminium outer tank.
5. Back-up electric heating element. Back-up electric heating element is an optional accessory in case of bad weather conditions. Its materials include copper, stainless steel and incoloy 800, among which incoloy 800 is the best choice. Make sure if you need a back-up electric heating element before buying a solar water heater.
All in all, next time when you plan to buy solar water heaters, take the above 5 aspects into consideration, and enjoy your green life.