Detail description about choose a solar water heater

Views: 2435     Author: Sunflower     Publish Time: 2011-11-04      Origin: Site


a. Is Solar Hot Water System a good investment for me?
The potential savings on water heating bills are affected the most by the type of fuel you are using to heat that water and the number of people in your home. If you are heating hot water for two or more people and you heat water with electricity or with natural gas, then you owe it to yourself to look at solar water system, it could be a great investment for you.
b. What about the pay-back period of the investment on Solar Water System? 
When you purchase a more efficient refrigerator, the decision to buy comes not from how long the savings generated will pay you back for your initial investment, but it comes from getting better service for a lower operating cost with a better rate of return. Solar water systems do just that. They provide quality hot water at a lower cost than heating with electricity or Natural gas.
It is important to remember that hot water is a constant daily expense; other large household appliances, like air conditioners and heaters, are seasonal expenses. Depending on you location (solar activity) and current hot water usage the annual electricity or gas saving will differ. However in a normal household that spends 20% to 30% of its electricity bill on hot water heating. Roughly speaking, a four person household needs 2 to 3 ㎡ solar collector to meet the hot water requirement, and 1 ㎡ aperture area of the solar collector will help save electricity 600 kWh and natural gas 80 m³ annually, with your electricity and natural gas cost per unit annual savings from solar water system can be worked out. In Beijing, the full cost of the purchase a Tsinghua Solar Water System may be recovered as quickly as 5 years. A Tsinghua solar collector should provide reliable operation for at least 15 years, and then you will definitely make considerable savings during the life of the solar hot water heater.
c. How do I choose a solar water heater?
Solar water heaters can be money savers and are environmentally friendly, but the initial purchase can be expensive. When purchasing a solar water heater, it is important to look at the different types of solar water heaters available to determine which type would work best in a specific home. A solar water heater can save a household anywhere from 50 – 80 percent of the current fuel cost of water heating, so choosing the very best option will help maximize that savings.
The first thing to look at is geographic location. Though solar systems are available for all climates, different regions will benefit from different types of heaters. A solar water heater is either pressurized or unpressurized. An unpressurized solar water heater is a thermosyphon system in which the storage tank is mounted above the collector and gravity pushes the heated water through the tank or you can use a circulation pump to push the hot water out , but these not appropriate for all homes.
A pressurized system does not need so many preparation, but normally the price is higher than previous one .Both types use collectors to take the energy from the sun to heat the water. An pressurized circulation systems uses a anti-freezing heat transfer fluid that circulates through the collectors. This fluid collects heat then transfers it to the water used in the home. Unpressurized systems circulate the water to be used through collectors.
So, when selecting a solar water heater, it should first be determined which type is appropriate for the climate in which it will be installed. Next, determine the amount of solar energy available. This will help determine the solar efficiency. The amount of hot water needed must also be noted. This determines the size and type of collector and storage tank. Finally, check prices and weigh all the other factors to determine the biggest savings and most efficient solar water heater for the location, size, and use of the home.
d. How to confirm the capacity of the solar water heater?
The ordinary water consumption of shower (45-50°C) is 30L for a man, and 40L for a woman. If the water consumption includes those in the kitchen, total water demand can be estimated according to 40-50L per person.
e. Is Tsinghua Solar Water System safe?
Yes. The majority of Tsinghua solar collector’s components are stainless steel, aluminum, polyurethane and free from electricity, so evacuated tube solar collectors are therefore eliminated fire risk and dangers related to electricity.
a. Can Tsinghua Solar Water System be installed anywhere?
Yes, JB and JR series can be installed on flat and sloped roof, SLL and SLU series (solar water system with remote storage tank) can be installed on flat and sloped roof, facade, and open ground.
There should be:
- No shading;
- South orientation of the collectors;
- Collector Tilt = Latitude of your location + 10°;
b. How to prevent thunder-strike effectively in installation?
The existing thunder arrester on the roof should be increased at least 50cm higher than the top of solar water heater before installing. Meanwhile the distance between the solar water heater and thunder arrester should be kept as 10cm at least. It is not allowed to connect the solar water heater with thunder arrester directly. The insulation protection should be added around the solar water heater when necessary.
c. What is the appropriate distance when placing the solar water heater in installation? 
After the installation, there will be a shadow at the back of the solar water heater, and the furthest distance of the shadow is called covering distance. The distance is usually 1.25 times of the height of solar water heater. The best distance between two solar water heaters in a line is 1.5 times of the solar water heater’s height.
d. Items to note for installation.
The installation person should try to make sure that the solar water heater face south without covering object in front of it.
Two wrenches should be used when connecting water nozzle with the pipes, one fixing the water nozzle and the other one fastening the connectors
The installation person should check if the silicon ring are fixed well in the tank before installing the vacuum tubes.
Lubricate the Dust-proof ring and the opening end of tubes with suds, and then put the dust-proof ring on the opening end of vacuum tubes. Insert the tubes into the tank along the direction of holes with slowly circumvolving. Then fix the vacuum tubes into the tail support carefully.
The nuts should not be fixed tightly when installing the tank, and they should be fixed when the vacuum tubes are installed.
The joint of the pipes should not bear pressure since it will cause the joint break easily.
The water nozzle and the air-vent should also have heat preservation, and the air-vent should be expedite, not blocked. The pipes should be covered with insulation, which is fastened by the adhesive tape.
The solar water heater should be fixed well, especially in the heavy wind area concrete and steel wire are suggested for installation.
a. Does Tsinghua Solar Water System generate hot water all seasons of the year?
It generates hot water on:
-Clear sunny day: Max.,
- Partially cloudy day: Moderate,
- Rainy or heavily overcast day :Nil;
Average 300 days in a year you will get hot water from you soar water system.
b. What about the rest bad solar radiation days?
For JB and JR series solar water heater, auxiliary electric heater is available;
For SLL and SLU series solar water heater, the back-up heating system is up to you, it can be electric heater or the boilers run on oil, gas, wood or even coal. No matter what is your choice, it must be well combined with the solar storage tank.
c.Can solar water heater be used in winter?
As we know, the sunshine hour is short, and the sun ray is weak in winter, the intraday water temperature is low. But after a continues 1-2days basking, the water temperature will be high enough for bathing (in sunny day).If it is cloudy day, electric heater will be needed to bath. Even though, there will be no problem for daily use such as cooking, washing the vegetables etc.
d. Can Tsinghua Solar Water System operates in frozen areas?
Yes. JB and SLL series solar water heater can be used in areas with temperature as low as -30°C; in continuous cloudy days, electric heater should be used to keep the water hot/warm. JR series with heat pipes and SLU series with U tubes operate normally in -40°C.
e. What can we do if the water in the tube freezes in winter?
There are two main reasons why the tubes will be frozen. One is because of the tubes. Inferior quality tubes may frozen (our products will not be frozen even at -30 °C ) The second reason is quality of the pipes. Bad selection and Insulation processing of the pipes caused them frozen. We utilize quality aluminum-plastic tubes which can withstand high and low temperature. Also can be installed to electric heating belt keep the solar water heater running even at about -10°C.Any way to solve this problem is to keep the water in the pipes running round the clock.
f. Will the solar collector be a fire hazard during hot, dry weather?
No. The THSolar collector’s components are all high temperature rated and non-flammable so even during strong MICOE with the circulation pump turned off (stagnation), the system will not catch alight or give off any sparks. The majority of the solar collector’s components are stainless steel or aluminium and glass. The manifold outlet should be fitted with a temperature safety valve, which will prevent the manifold temperature from exceeding 99°C / 212°F.
g. Does Tsinghua Solar Water System generate high temperature water?
Yes, the system can be designed to give you an average output temperature as high as 60-85℃. If you consider that when having a shower the water temperature is usually around 32-43°C, and scalding can occur at 54°C, this temperature output is more than sufficient. In fact in some countries you may have to fit a thermostatic tempering valve to your house plumbing to conform to government health and safety regulations. This valve will temper water down to between 43 and 50°C.
h. Can Tsinghua Solar Water System be used for a large-scale hot water production?
Yes. Solar collectors can be connected in series or parallel to provide large scale hot water production for commercial settings such as a school, hotel, office building etc. There is really no limit to the size of the system! For large scale hot water production, SLL series is recommended for its cost-effectiveness.
i. What is the best time for solar water heater water filling?
The stagnation temperature of the vacuum tubes can reach 240°C. The vacuum tube will explode if you fill cold water at that time. In order to prolong the serviceable life of vacuum tubes, the best time for water filling is at night or the next morning.
What are the ordinary maintenance? How much money shall be spent on maintenance?
The vacuum tubes should be changed when there is something wrong with the tubes.
The tank should be changed when it leaks
The tank should be changed when it bursts or stucks.
When the accessories breaks, the faulty accessories should be changed.
Maintenance is minimal for the system. Only Periodic glass tubes cleaning and the check for leakages and valve functioning are necessary. If one of the tubes is broken, it is also fairly inexpensive and easy to be replaced. Turn to your local distributor he will stock spare tubes. JR series and SLU series solar water system can operate with several broken tubes, but the efficiency will be negatively affected, so it is recommended that broken tubes be replaced immediately.
a. Why tubes have different colors?
Coating is affected by the undulation of voltage and air pressure. The more coating layers the tube has, the greater possibility it is that the color of the coating is difficult to control. Generally, it is natural that the color is a little different while it is abnormal that the color is motley.
b. What is the function of the controller and the sensor?
The main function of the controller is displaying the water temperature and level, auto water filling, and controlling the electric heater.
c. Why the flux in the outlet is small?
The common solar water heater is non-pressurized that two reasons can cause the small flux.
One is the solar water heater is not assembled at a high position. The vertical gap between the heater and nozzle is not large enough (especial on the top ground).The way to solve this problem is to increase the height of the heater or enlarge the diameter of the pipes.
Another problem is the pipes are bending. The way to solve this problem is to re-settle the pipes.
The third problem is that the something blocks the outlet, inlet or the pipes. The method to solve this problem is to call us to examine it.
d. Are all-glass evacuated tubular collectors more efficient than flat plate collectors?
On average, yes. Evacuated tubular collectors are superior to flat plate collectors in a number of ways:
(a) Due to the cylindrical shape of the evacuated tube, the sun is perpendicular to the surface of the glass for most of the day. Flat plate collectors have the disadvantage that the sun is only perpendicular to the collector at noon and thus a proportion of the sunlight striking the surface of the collector is likely to be reflected.
(b)As the name suggests, air is evacuated from the evacuated tube to form a vacuum. This greatly reduces conductive and convective heat loss from the interior of the tube. As a result wind and cold temperatures have minimal effect on the efficiency of the evacuated tubular collector.
(c)Tsinghua all-glass evacuated tubular collectors can be used in subzero temperatures without the system sustaining damage. Flat plate systems often require expensive and complicated “antifreeze” systems to be installed.
(d)Evacuated Tubes are strong, long lasting, and should one be broken, inexpensive and easy to replace.
(e)Due to the high efficiency absorption of solar radiation even during overcast conditions, combined with excellent insulation properties of the tube, evacuated tube collectors will heat water all year round (back-up heating system required for particularly overcast or rainy weather).
(f)Due to the various advantages of evacuated tube collector over flat plate collectors, a smaller collector can be used to provide the same heating performance. For example, a standard household of 4-5 people would usually require a 200-250L water storage tank. Depending on your location, only 2-3 ㎡ of aperture area would be required to efficiently heat this volume of water.
(g)Flat plate solar collector can produce similar heat output to evacuated tubular collector, but generally only during warm, still, sunny conditions. When averaged over an entire year, evacuated tube collector heat output per net ㎡ of collector area, is superior to flat plate.

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