© 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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