News & Knowledge

With the OEG 4flex® heat pipe, high-quality low-iron soda lime glass is exclusively used. These tubes have been manufactured in Europe with a 30-year experience. That is the reason why we are able to give you a 20-year warranty on the vacuum of the tubes.

With other solar tubes in the market, borosilicate glass is used. This might draw helium in case of high temperatures and thus impair the vacuum. Very often, you will also find visible lines from glass processing with air pockets which might lead to a higher fragility.

With the OEG 4flex® heat pipe, the unique temperature limitation in the capacitor switches off at 90°C automatically. Only when the temperature decreases, the generation of energy will be resumed. Thus, all components and the solar fluid is protected.

No other solar tube in the market provides this advantage. They only have empty capacitor heads and no temperature limitation which leads to excessive thermal load in the system and solar fluid.

With the OEG 4flex® heat pipe, the capacitor head is conneced with the tube via a high-quality corrugated stainless steel pipe connection. It intercepts tensions which are created by different temperatures.

Other tubes in the market have rigid connections, which are not able to compensate tensions between glass and capacitor.

With the OEG 4flex® heat pipe, the tube is completely welded and 100% controlled. Thus, we can achieve a long-lasting vacuum in the heatpipe tube.

Other tubes used in the market have seals with plugs.

If you would like to pay by direct debit, you will find the current forms for the SEPA direct debit in the Service section under Payment & Shipping. There please click on the download.

A solar system mainly consists of the following components: collectors, pump group and storage tank. The pump group transports the solar liquid heated by collectors into the storage tank where its water is thus heated up. When the water in the tank has reached its maximum temperature, the pump group switches off and no more heat is taken away from the solar collectors. This is why they usually get so hot. So hot that the solar liquid vapourises in conventional collectors. As a consequence the solar liquid ages rapidly or even gets harmed. Additionally, all the components are afflicted by the high temperatures. In order to protect the solar liquid as well as the components, the 4flex+ tubes provide a patented overheat protection in the capacitor. As soon as the temperature in the capacitor rises up to 90° C, bimetal discs lying on top of each other close a valve that prevents more working fluid from rising from the heat pipe into the capacitor. It also prevents from giving off heat to the solar liquid. Thus it is effectively avoided that the solar liquid vapourises (see right part of the picture). When the storage tank can take up heat again, when the pump group works again, when the solar liquid is recirculated and the temperature in the capacitor drops below 90° C, the bimetal discs open the valve and the system returns to its normal operating state.

The OEG heat pipe vacuum tube collector 4flex is one of the most modern solar tubes and satisfies highest demands on efficiency, safety and flexibility.

In the 4flex solar tubes there is a copper absorber in a vacuum glass tube. Due to the vacuum, heat losses are minimized, like in a thermos flask.

At the rear side of the absorber there is copper pipe also placed in a vacuum: the heat pipe. It is filled with a little amount of working fluid. The vacuum inside the heat pipe causes the fluid to vapourise starting from a temperature of 28° C.

With solar radiation, the absorber takes up the energy and warms up. This is when the working fluid in the heat pipe starts to boil and changes from a liquid to a gaseous state. The resulting vapour rises to the top end of the heat pipe into the capacitor. Via the capacitor the heat pipe conveys the heat to the solar liquid and the working fluid condenses again and flows back down through the copper tube. If there is sufficient sun radiation, this cycle is repeated continuously..

The dry connection of the heatpipe tubes in the 4flex headers, the small amount of working fluid and this patented overheat protection ensure a particularly high operating safety of the 4flex. Due to the dry connection, individual tubes can be exchanged if necessary without having to drain the solar liquid from the solar unit. Modern click-fit technology allows fast, easy and flexible one-man assembly. Individual tubes can be plugged together in order to generate solar collectors of a perfectly aligned size.

With one of the latest state-of-the-art productions, OEG has built an extensive, technically high-quality storage tank portfolio during recent years. You will not only find the storage take you are looking for, but also in the exact size. You can also choose between different colours, like silver, white, blue or red.

And of course: Made in Germany ! With a 10-year warranty !*

*if installation and annual maintenance are carried out by specialized craft businesses. With enamelled storage tanks, the use of a Correx inductive anode is a necessary requirement.

Fresh and hot water is an essential component of life. Whether used for drinking, cooking, showering or washing your Hands, having unlimited amounts of drinking water at any temperature is one of the main achievements of modern society. It is very often taken for granted that the water quality is hygienically perfect. Conventional drinking water tanks, which store a large quantity of heated water for a long period of time, cannot always fulfill these requirements without exception. Largely dimensioned drinking water tanks with low storage temperatures and a temperature layering are energetically common (e.g. a heating system with heat pump and solar thermal support). These factors, however, add to the formation of a sediment layer at the bottom of the tank, which also presents an ideal breeding ground for bacteria (e.g. legionella).

That is the reason why the freshwater technology applied in hygienic tanks has so many advantages for the hygiene of water.

These hygienic storage tanks meet the latest thermotechnical and water-hygienic requirements. Their construction is fundamentally different from those common, large-volume drinking water storage tanks. With hygienic storage tanks, a built-in corrugated stainless steel pipe separates drinking water from heating water and serves as a powerful heat exchanger at the same time. Thus, all the advantages of a buffer storage tank are combined with those of an instantaneous water heater.

The heating water actually serves as a heat storage tank while the drinking water runs through the corrugated stainless steel pipe only when required and gets heated as a result. In this way, the consumer gets hygienically perfect fresh water at the desired temperature at any time.