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How to choose a water heater?

1. According to the brand of the product. Different brands mean different quality and different indemnity of after service.

2. According to the element for heat collection. In accordance with the material, the heat collector of flat-plate type includes pan-aluminium, pan-copper, recombination of copper and aluminium, etc. According to the coating for collecting heat, there are anodize coating, black paint coating, etc. The degree of sealing decides the quality, and the panel sealed well has long lifetime and high efficiency. So does the vacuum tube, the quality brand ones have high vacuum degree, uniform plated layer, uniform thickness, high heating efficiency, small heat consumption, long lifetime, quality insurance, and it is good enough for design requirements.

3. According to the material and the crafts it uses. Different materials mean different quality and different lifetime. The stainless-steel is nobility, sumptuous and is better than others such us the aluminium, angle block, colored steel, etc., the thick ones are superior to the thin ones, the imported ones are more expensive than the ones home-grown; the heat insulation effect of poly ammonia adepts foaming wholly is superior to the foamed plastics panels; formation in whole is better than separated (rivet the foreskin outside with rivets); focusing reflection panel is better than the flat-plate type.

4. According to the function, lifetime and safety. Take the function of feeding water automatically for example, there are floating hall type and electric magnetic valve type; and the electric heater includes electrical control type (rather safe) and no electrical control type (not rather safe). Some functions cannot undergo the time check, which seem to be advanced, you must consult the lifetime and the guarantee time clearly lest being cheated.

5. According to the after service. The after service is very important because of the long lifetime. The quality brand products and the agents having actual strength have insurance credit, and they will not have risk the whole products??? after service because of the management risk of several agents. You can feel relieved and save worry when using it, and it has indemnity for after service.

how to choose a water heater

How many kinds of solar water heaters there are?

1. The first era is sealed and solarized heater. This is a whole heater combining gathering heat and accumulating heat into one, which is generally made up with two to there round tubes painted black. The blank coating absorbs heat to heat the water. The advantages: simple structure and lower cost of construction, and the disadvantages: too quick rejection of heat, you can not use it in winter or rainy day. This product is only used in outlying villages and now has been superseded by the large.

2. The second era is flat-plate solar water heater. It is made up with plat-plate heat collecting water tank, and generally runs in natural circulate style. The flat-plate heat collector consists of the body for absorption of heat, transparency coverer, insulating layer for back and side face, and framework. The body of flat-plate heat collector for absorption of heat, produced by nation factories, includes multiple-unit of copper and aluminium plate, copper all-over plate and flat case welded by stamping from stainless-steel, etc.

They all insure the cleanliness of water and their side toward the sun paint acrylic acid black lacquer or selective anode oxidated colored coating. Their insulating material for back and side face often use the board of foaming poly ammonia adeps, rock wool and poly styrene (it will shrink when heated, must be separated from the absorbing body by glass wool or reflective thin wool), the framework usually uses the aluminium shape specially projected (inlay the glass and sealing materials).

The transparent coverer uses the 5mm flat-plate glass. Its features: lower cost of construction, high rate of heat, it can produce hot water when sunny; but its rejection of heat is too quick and the heat consumption is too much, in cloudy day or winter the temperature of water will not be easy to be high for bathing.

3. The third era is vacuum tube water heater. It usually adopts natural convection for exchanging heat, which is made up of several glass vacuum tubes for heat collection insetting the water tank directly. There is silica gel band between each vacuum tube for collecting heat and the hole of water rank. The vacuum tube transfer heat through super conductor in the copper heat tube rather than water, so the rate of heating is high and the tube does not make water scale.

Many water heaters in our country adopts glass tube for heat collection, which is made out of the concentricity sleeve pipes of high borosilicate glass, whose diameter is 37mm, 47mm, or 58mm. The space between the two tubes is drawn to be vacuum of 5*10-3pa, and the outside of the inner tube deposits some gradating aluminium nitrogen/aluminium. The solar spectrum absorbs the coating selectively (the rate of absorption is a=0.90~0.92, the rate of emission is b=0.06~0.1), and the length of the tube has two kinds: 1.2m and 1.5m. The heat consumption rate of the vacuum tube is small (U=0.55~1.2W/m2.0C), so you can use the heater both in rainy and varied weather.

The features of the heater is as follows: high heating rate, quick heat absorption, slow heat elimination, small heat consumption; as long as the radiant of the sun reaches the command, you can also use it in winter and rainy days; it also has sumptuous appearance long lasting even more than 15 years and small areas, and it suits the family use well.

Between the flat-plate water heater and the vacuum tube water heater, which is better?

1. The vacuum tube heater is better in the effect of absorption. With same area for heat collection, the vacuum tube heater can bring out more hot water, but the area of flat-plate heater usually is large, so the effect of it is also good.

2. In the heat consumption the vacuum tube heater is better. The plate type has gel band for sealing, but is not good contrasting to the vacuum tube with high vacuum, this is the reason that why the plate type does not use well in winter and rainy days. The vacuum tube type absorbs heat easily and has small heat consumption because of the vacuum layer spacing out the outside, so it can be used in both winter and rainy days.

3. From the economy, the plate type uses cheap materials and boards for heat absorption with lower costs of constructions. The holder of it usually uses angle block, and the outside coverer of water rank is made of colored steel. Its rude material is cheap, so it is suited for the families with lower incomes. The vacuum tube type has chichi appearance and is endurable, so it is suited for the families with high incomes.

4. With the view of their lifetimes, generally, the flat-plate type is 10~15 years and the vacuum tube type is 15~20 years.

5. From the materials, the flat-plate type usually uses aluminium, copper, angle block, flat glass, etc. and the vacuum tube type uses stainless-steel, high boron silica glass, etc. and the latter is sumptuous and endurable.

What are the merits of solar water heater?

1. Economic. The light of sun is free, you only need cost 2000~3000 £¤ on instruments for 15~20 years use, which saves much fees for coal gas and electric.

2. Convenient. Place it on the flat of your house, and you have hot water supply every moment without waiting. It is very convenient.

3. Safe. You do not need to be terrified of coal gas poisoning, current leakage and other thing except scalded by the too hot water.

4. Environment protection. It does not emit any exhaust air to pollute the environment, so it is a green environment protection and energy-saving product.

5. Popular. Solar water heater will replace the traditional coal gas heater or electric heater. You are a person noticing environment protection and knowing enjoying life and you are in the beginning of the tidal current if you use it now.

If the Modern solar water heater can be used in winter?

It can boil the water in summer and has no problem in spring and autumn using, it also can be used in winter..In winter, it only needs 2~3 hours sunshine whether in sunny days or varied rainy days, then the water is hot and can be used directly; in continuous rainy day in winter, the temperature of the water will rise for 20~30 degree. Because the beginning temperature is too low (sometimes is 5~6 degree), the water cannot be used directly, but you can use the coal gas or electric as assistant to make the temperature rise for several degrees, then the water are hot enough to bathe in.

Compare with raising the water temperature from tap water to bathing water, you save a large part of the coal gas or electric. According to the need of clients, Modern Co. may provide electric heating instruments or make the water of solar heater pour into coal gas heater to be reheated. You can save 80% electric or coal gas a year if you use the solar heater.

If living on the bottom of a high building, can I install the solar water heater?
Of course you can. The water from the bottom have force, so you use it more comfortable. Some people are worried about that water will get cold when flowing from so high place, but it is superfluous. In fact, water will not get cold so fast because we adopt the insulating aluminium plastic multiple-unit tube for our water pipe.

Solar Energy

Solar energy is the cleanest and most inexhaustible of all known energy sources. Solar radiation is the heat, light and other radiation that is emitted from the sun. Solar radiation contains huge amounts of energy and is responsible for almost all the natural processes on earth. The suns energy, although plentiful, has been hard to directly harness until recently.

Solar Energy can be classified into two categories, Thermal and Light. Photo-voltaic cells (PV) use semiconductor-based technology to convert light energy directly into an electric current that can either be used immediately, or stored in a battery, for later use. PV panels are now becoming widely used as they are very versatile, and can be easily mounted on buildings and other structures. They can provide a clean, renewable energy source which can supplement and thus minimize the use of mains electricity supply. In regions without main electricity supply such as remote communities, emergency phones etc, PV energy can provide a reliable supply of electricity. The disadvantage of PV panels is their high cost and relatively low energy conversion rate (only 13-15%). Thermal solar on the other hand has average efficiency levels 4-5 times that of PV, and is therefore much cheaper per unit of energy produced.

Thermal energy can be used to passively heat buildings through the use of certain building materials and architectural design, or used directly to heat water for household use. In many regions, solar water heaters are now a viable supplement or alternative to electric or gas hot water production.

Thermal energy obtained from the sun can be used for a number of applications including producing hot water, space heating and even cooling via use of absorption chilling technology.

Using solar and other forms of renewable energy reduces reliance on fossil fuels for energy production, thus directly reducing CO2 emissions. CO2 emissions contribute to global warming, an environmental issue which is now of great concern. The average household can reduce CO2 emissions by as much as 20% by installing a solar collector.

Flat plate thermal solar collectors have been in use for several decades, but only in relatively small numbers, particularly in Western countries. Evacuated tubes have also been in use for more than 20 years, but have been much more expensive than flat plate, and therefore only chosen for high temperature applications or by those with money.

In recent years the production volume of evacuated tubes has exploded, resulting in greatly lower manufacturing and material costs. The result is that evacuated tubes are now similar in price to flat plate, but with the insulating benefits of the evacuated tube, they are set to become the default choice for thermal solar applications worldwide.

The days of a 15 year payback time for a solar collector are over – we can now achieve payback times of less then half that!

There has been a great deal of information in the media over the past few years about global warming and the role of CO2 emissions. 2003 saw extreme weather conditions and a heat-wave throughout Europe, clear evidence of the realism of this problem, commonly referred to as the “green house effect.”

Burning fossil fuels such as coal for electricity production, and gas for water heating both release large amounts of CO2 into the atmosphere, thus contributing to this environmentally harmful phenomenon. By using renewable energy sources such a Solar Thermal, Solar PV, Wind, Hydro and Geothermal, reliance on fossil fuels can be minimised, thus directly reducing CO2 emissions.

On average for every 1kWh of energy produced by a coal power station, 1kg (2.2pound) of CO2 is produced. Burning natural gas for electricity production or water heating produces about 450grams of CO2 for every kWh of energy produced.

In the average household, water heating accounts for around 30% of CO2 emissions. By installing a solar water heater, which can provide between 50-70% of your hot water heating energy needs, you can reduce your total CO2 emissions by more than 20%.

Solar collectors are reducing CO2 emissions by more than 5000 tonnes per year, with collectors installed in the UK, USA, New Zealand, Germany, France, Sweden, Italy, Hungary, Portugal, Jordan, Lebanon, Australia, Canada, Mexico and many other locations. (One metric tonne = 2200 pounds)

What is solar insolation?
Amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Basically how much sunlight is shining down on us.

Why is knowing the insolation level useful?
By knowing the insolation levels of a particular region we can determine the size of solar collector that is required. An area with poor insolation levels will need a larger collector than an area with high insolation levels. Once you know your region’s insolation level you can more accurately calculate collector size and energy output.

What units are used to express Insolation levels?
The values are generally expressed in kWh/m2/day. This is the amount of solar energy that strikes a square metre of the earth’s surface in a single day. Of course this value is averaged to account for differences in the days’ length. There are several units that are used throughout the world.

The conversions based on surface area as follows:
1 kWh/m2/day = 317.1 btu/ft2/day = 3.6MJ/m2/day

The raw energy conversions are:
1kWh = 3412 Btu = 3.6MJ = 859.8kcal

Is my region’s insolation level low, moderate or high?
The following scale is a basic guide for insolation levels. Although a value of 5 is not considered very high during the summer months, as an average annual value this is very high. You will see that in central Australia, which is a hot, sunny place, the annual average insolation is 5.89.

You may compare you location to the following two extreme locations.
Average annual insolation levels:
Central Australia = 5.89 kWh/m2/day – Very High
Helsinki, Finland = 2.41 kWh/m2/day – Very Low