© Gernot Walter

Heating like the sun

It takes a lot of energy to heat large buildings, making it that much more important for heat to be where it’s needed and not get lost when gates are opened. To avoid such losses, radiant tube heaters are often used. They heat like the sun. But until recently, they also had room for improvement.

Gate up, heat out. If logistics centers, airplane hangars or factory buildings used conventional heating systems, they would lose heat every time the gates are opened or when large amounts of air are extracted for production purposes. That’s why they usually use radiant tube heaters that don’t heat the air but instead work like the sun.

Radiant tube heaters include gas-powered heating units that produce heat with infrared radiation. They are usually suspended under the ceiling at heights of four to twelve meters and heat objects, walls, floors and also people with infrared radiation. They work by heating a heat-resistant tube to a temperature of 580 degrees. A reflector above the tube deflects the infrared radiation toward the floor and the people below.

Constant air supply

Until recently, Schwank, the world market leader in gas-powered infrared heaters, used a burner to produce a flame inside a steel tube. To produce the right air-gas ratio for combustion, a blower supplied air to the flame. The output was regulated solely through the amount of gas supplied.

“I’ve worked a lot with ebm-papst. They were always a step ahead.”

Dr. Friedhelm Schlößer, Managing Director of Schwank GmbH

“If you modulate by keeping the amount of air constant and reduce only the amount of gas, at low output ranges that unavoidably leads to inefficient combustion and lower output,” explains Dr. Friedhelm Schlößer, Managing Director of Schwank GmbH. “That’s better than not modulating at all, but it’s not in compliance with the current EU product efficiency requirements.” That’s one of the reasons why the company decided a year and a half ago to develop a better solution with ebm-papst.

Radiant tube heaters work at heights of up to twelve meters using infrared radiation — just like the sun. (Photo: Schwank GmbH)

“I’ve worked a lot with ebm-papst,” says Schlößer. “They were always a step ahead. For our deltaSchwank radiant tube heater, we use ebm-papst’s NRV 118 gas/air composite system for lower outputs and the NRV 137 for higher outputs. Both include a gas valve, an EC gas condensing blower and a gas-air mixer, the so-called Venturi tube. That makes us the first manufacturer of radiant tube heaters worldwide to use EC gas condensing blowers.”

Efficiency of 95 percent

The solution has several advantages. Since the EC blower can be smoothly modulated between three and 30 kilowatts, the output of the heaters can be adjusted to the building’s actual heating needs without a loss of efficiency due to excess air. The heaters can reach efficiency levels of up to 95 percent.

The environment also benefits. “Modulating units do especially well in the transitional periods of spring and fall or in mild winters when 100 percent output isn’t needed. With the gas/air composite system, now we can achieve the best efficiency across all output ranges. That results in a further significant drop in gas consumption.”

“That makes us the first manufacturer of radiant tube heaters worldwide to use EC gas condensing blowers.”

Dr. Friedhelm Schlößer, Managing Director of Schwank GmbH

Cleaner combustion means the heaters emit 20 percent less CO2 and 55 percent less nitrogen oxides. Schwank thus exceeds strict EU guidelines such as the Ecodesign (ErP) Directive and can offer its customers a product that’s ready for the future. Thanks to EC motors, the heaters use up to 72 percent less electricity.

All from a single supplier

Schwank used to buy every component from a different manufacturer. Now it gets the entire gas/air composite system from ebm-papst. “That gives us more time to concentrate on the heating system,” says Schlößer. “And of course on developing more new products.”


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