SCHOTT solutions no. 1/2015 > Systems Engineering

Systems engineering
According to ATEC, the glass tube heat exchanger for retrofitting is the first of its kind that is ­suited for nearly all types of heating systems and has received approval for use. Photo: SCHOTT/S. Brüggemann

Recovering energy intelligently


According to ATEC, the glass tube heat exchanger for retrofitting is the first of its kind that is ­suited for nearly all types of heating systems and has received approval for use.


Thilo Horvatitsch

Reducing energy consumption is a key objective of modern building refurbishment. To Guido Jobst, this simply isn’t enough. ”This also includes factors such as efficiency, conserving resources, and the overall energy balance of a measure,” notes the Managing Director of the German company ATEC Abgas-Techno­logie who then offers a practical example of this. If a low-temperature boiler has already been operating in a single-family home for ten to fifteen years, the typical energy consultant would recommend replacing it with a condensing or combi-boiler, perhaps including solar support, to increase energy efficiency. ”What they don’t consider, however, is that boilers that are replaced are generally high-quality products that would do the job for up to another fifteen years,” Guido Jobst explains.

The head of ATEC, who has been active in the flue gas technology industry for 25 years, therefore decided to convert a method taken from large boiler technology and adapt it to private homes. In industrial plants, condensing gas boilers are suspended behind the large boilers within the flue gas outlet in order to use the high flue gas temperatures to generate energy. By doing so, condensing boiler technology is upgraded, and the existing boiler can still be used.
glass tube heat exchangers
Managing Director Guido Jobst (right) sees great potential for his glass tube heat exchangers. ATEC offers the system for retrofitting oil and gas boilers with overpressure burners or in combination with new appliances such as CHPs. Photo: SCHOTT/S. Brüggemann
Up until now, this technology was not available for small boilers. However, ATEC developed a solution. To achieve these results for small boilers, a heat exchanger ensures that the water vapor condenses around the special glass tubes that contain exhaust gases of up to 270 degrees Celsius and does not escape through the chimney. The heat that is obtained through condensation then heats up the heating water that flows through the tubes.

The DURAN® borosilicate glass tubes that are used here serve as key components of this system. They are extremely strong and corrosion-resistant to sulfuric acids and other combustion residues that result from this process. ”Neither metals nor plastics could be used in these components. And because we wanted to offer a high-quality product, we were looking for a premium supplier of glass solutions with experience in systems engineering,” Jobst explains. SCHOTT convinced him thanks to its decades of experience as a supplier to the heat exchanger industry, which includes large brewery plants. In addition, the technology company provides precise and solid finishing of the glass tubes’ ends and thereby made the system’s much needed tightness and performance possible – a must for flawless operation and the product guarantees that are given to customers,” adds Jobst.

According to ATEC, the glass tube heat exchanger for retrofitting is the first of its kind that is suited for nearly all types of heating systems and has received approval for use. A vacuum blower for active transport of flue gases to the outside makes this possible. This function allows for the heat exchanger to be connected to a boiler with a forced air burner for natural gas or fuel oil.
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Glass tube heat exchanger for retrofitting


The investments necessary in order to use this innovative product are less than half of the costs of exchanging a low-temperature boiler with a condensing model. The bottom line is that, based on calculations for homes, installation of a heat exchanger pays for itself within four to nine years. And money is saved during operation as well. For example, annual consumption of 2,000 liters of oil can be reduced by 150 to 300 liters.

Guido Jobst also emphasizes the positive effect on the environment. ”According to chimney sweepers’ statistics, there are approximately 1.75 million fan-driven heating systems that are capable of supplying 25 to 80 kW and are up to 15 years old in Germany. If we were to retrofit only 500,000 of them, the environment would be positively affected by an annual reduction of 600,000 tons of CO2 gases.”

To tap into this market even further, ATEC now offers new systems comprised of a combination of a heat exchanger and CHP (­co-generator). For the future, Guido Jobst plans to retrofit the heat exchanger so it can be used with pellet boilers. ”The potential is there,” he claims. <