Solar Geyser: FES Friendly Energy Solutions

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The FESolutions water heater is designed and manufactured in South Africa, to the highest quality standards with our local conditions in mind. These systems are all SABS approved and have been recognized as having one of the highest efficiency ratios (Q Factor) on the market. The most important part of any hot water geyser is the internal boiler tank. To combat corrosion, most local manufacturers utilize a mild steel tank with a internal vitreous enamel coating, which can be venerable to cracking, and therefore exposing the tank to rust.

By comparison, all our boilers are manufactured from 444 Stainless steel, and are robotically welded to ensure consistency and reliability for many years.

444 Stainless steel is vastly superior to mild steel, and allows the inner tank to be virtually immune to the aggressive waters that can be found in our Country. It is highly chemically resistant, and is not affected by high chorine content found in our water. The only exception to this is Sulphur Reducing Bacteria can contribute to corrosion of metals. For added protection, our geysers incorporate a sacrificial anode to safeguard the tank even further.

The end result is a 10 year warranty on the boiler (subject to our T&C’s).

All our installations are carried out by our team that are in house trained, PIRB and Eskom approved plumbers, as well as ECB registered electrical contractors.

Our water heaters are truly excellent products, and compare favourably with any other solar system in the market. Our commitment to quality is non-negotiable, and your peace of mind comes as part of the deal.

Due to the recent loss of Eskom rebates, our company has implemented a RENT to OWN option to assist our clients, and to improve our penetration in the market. The figures are very much dependant on the systems you install and can range from as low as R700pm with a R2500.00 deposit. After a proper assesment, your consultant will be able to work out a package to suit your pocket.

How the evacuated tubes work

solar geyser tubes

How do Vacuum Tube Solar Collectors Work?

The vacuum tube is a key component of the solar collector. Each vacuum tube consists of two borosilicate glass tubes that have high chemical and shock resistance characteristics. During the manufacturing process the outer side of the inner tube is coated with a heat absorbent material. The outer tube and the inner tube are then sealed together. During the sealing process all gas is evacuated between the outer tube and inner tube. This vacuum is maintained by a barium gas getter which absorbs any residual gas. The vacuum virtually eliminated any heat loss from the inner tube by either conduction or convection.

For improved performance the outer surface of the inner tube is coated with three different materials consisting of a copper based reflecting layer followed by an absorbance layer that absorbs heat followed by a remittance reducing layer that helps retain the absorbed heat. The combination of these three layers help to solve the typical problem associated with heat remittance performance; the higher the temperature the higher the remittance factor. The heat absorbance efficiency of the tube has been increased by 14% while the remittance has been reduced by 30% – 40%. These gains in efficiency translate into a higher stagnation temperature of 270°C.

solar geyser tubes 2

This heat, which builds up on the surfaces of the inner glass tube, gets transferred to the heat pipe by a series of aluminum heat absorption fins. As indicated in the cross section below these aluminum heat fins are in contact with the inner surface of the inner tube and as the fin heats up the heat gets transferred to the heat pipe.

The reason for creating the vacuum is to alter the state of the liquid in the hollow space. At sea level water boils at 100°C, but if you climb to the top of a mountain the boiling temperature will be less that 100°C. The decrease in boiling temperature is as a result of the decrease in air pressure as one move to a higher altitude. This principle forms the basis of the heat pipe. By creating a vacuum in the interior of the heat pipe the air pressure in the inside of the heat pipe is minimized. This low pressure environment lowers the boiling point of the water in the heat tube to + 25°C so that when the the heat pipe is heated above 25°C the water vaporizes.

This vapor rapidly rises to the top of the heat pipe transferring heat to the condenser bulb at the top end of the heat pipe. The condenser bulb has a much larger diameter than the heat pipe shaft; this is to provide a larger surface area over which the heat transfer can occur. The condenser bulb fits into the manifold’s heat conductor bushing. As the condenser bulb heats up it transfers heat, via the bushing, to the water flowing through the manifold. This transfer of heat causes the vapor to condense into a liquid state (water) and the water returns to the bottom of the heat pipe where it heats up again and the process is continually repeated.

Prior to being approved for use each heat pipe is tested for heat transfer performance and exposed to temperatures of 250°C. It is for this reason that the copper heat pipes are relatively soft.

Even though the boiling point of the water has been reduced to + 25°C the freezing point still remains at 0°C. Because the heat pipe is located within the evacuated glass tube, overnight temperatures as low as – 20°C will not cause the heat pipe to freeze.


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