When the drive belts suddenly stopped working, Peter Halblaub knew he was in for a real chal­lenge. It was a warm day in October 2019, and he was standing in front of the venti­la­tion system that had provided the Neckar­sulm shop­ping center with fresh air for almost 30 years. At least, that was what it was supposed to do. But at this moment, every­thing had stopped working. “We had replaced the drive belts not long before, but now the system had stopped again,” recalls Peter. He is the facility manager at Sauter FM GmbH, and is respon­sible for the shop­ping center building and its tech­nical systems. “It was clear to us that the system would break at some point, but it surprised us that it went so quickly.”

He contacted building tech­nology specialist Wolf­gang Stickel, who confirmed his worst fears: “The axle bearing was completely faulty. As a result, the fan wheel had dropped and eaten into the housing.” He ruled out the possi­bility of reassem­bling the axle layer-by-layer due to the enor­mous mate­rial abra­sion. What was more, the entire system simply no longer met modern-day require­ments. “When our venti­la­tion was installed, energy effi­ciency wasn’t a major concern. That’s different now,” says Wolf­gang. That made it clear that a new system was needed.

The FanGrid ensures effi­cient air perfor­mance and is so quiet that the shop­ping expe­ri­ence remains undis­turbed. (Foto: Tobias Gerber, Fotogloria)

A race against time

“But it was also clear that we had to act quickly,” Peter recalls. “A shop­ping center without working venti­la­tion is unthink­able!” So he started looking for solu­tions and suppliers, checked whether they were able to deliver, and whether they met the criteria on which Sauter FM’s projects are based: the devices had to be modern and energy-effi­cient, cost-effi­cient to main­tain, and avail­able quickly. The price of the system also had to be right. “We can’t just install some­thing, hope for the best, then find out we’ve made a mistake and expect our customers to put up with it.” During his research, he came across ebm-papst and found that every­thing there was suit­able – the prod­ucts, the delivery time, the service, the price. Wolf­gang Stickel was awarded the contract and contacted the venti­la­tion specialist company from Hohen­lohe with an initial idea. “I knew exactly what I wanted,” he says.

“The noise level is very low, even though there’s so much power behind it. The RadiPac fans run very quietly and highly effi­ciently.”

Peter Halblaub, Facility Manager at Sauter FM GmbH

“I described the problem with our venti­la­tion system to Rudi Wein­mann from ebm-papst’s sales depart­ment, and told him what I needed from the new devices.” In an on-site appoint­ment with Wolf­gang, Rudi was able to get an overview of the situ­a­tion and discuss the best solu­tion. They quickly found one using the ebm-papst design program FanScout: a FanGrid, i.e. a fan wall consisting of several RadiPac centrifugal fans with EC tech­nology, was to be the solu­tion. “I checked the offer, checked the measure­ments again, and then we imple­mented it,” says Wolf­gang.

Plasma cutters tackle colossal steel machine

What was a straight­for­ward solu­tion, was in fact anything but straight­for­ward to imple­ment. When the old system was installed 30 years ago, the fan wheel, a steel colossus that weighed several metric tons, was installed via the roof using a crane, and then bricked in. With a diam­eter of 2.5 meters and a length of 2 meters, it did not fit through the existing door. So to get the huge steel struc­ture out of the room, a bigger piece of equip­ment was needed. A demo­li­tion company got to work with plasma cutters, and trans­ported the parts – once cut down to size – through the door to the outside indi­vid­u­ally. That was a really weighty chal­lenge.

Peter Halblaub and Wolf­gang Stickel are impressed by the power of the sixteen Radi­Pacs. (Foto: Tobias Gerber, Fotoloria)

Fan on fan

Another chal­lenge was posed by the instal­la­tion area that was avail­able for the design and construc­tion of the new system, as this was just 5 x 10 meters in area, and did not offer a lot of space. “Pipes and cables made it even trickier to get every­thing to fit,” says Wolf­gang Stickel. But the project team had decided on a modular design for the FanGrid. Instead of a huge fan, Wolf­gang and his team installed 16 Radi­Pacs, each one in size 400, into a large FanGrid. He simply carried the small fans through the door. “A solu­tion with nine fans would have been just about enough, but only just. We wanted to be on the safe side, so we decided on a higher number of fans,” says the certi­fied elec­tri­cian. “There were some skep­tics who doubted that we could actu­ally install 16 fans in the room, but I knew we would manage it.”

Vibra­tions don’t stand a chance

Bit by bit, Wolf­gang and his co-workers installed the Radi­Pacs and connected them. They paid partic­ular atten­tion to the rigidity and stability of the mechan­ical connec­tions. “When this many indi­vidual fans are assem­bled into a large fan wall, reso­nance vibra­tions can occur. If the wall develops reso­nance vibra­tions, then in the worst-case scenario, it can collapse.” In addi­tion, each fan was cali­brated indi­vid­u­ally, and overall reso­nance measure­ments were conducted. To keep the vibra­tions low, the RadiPac centrifugal fans are equipped with reso­nance detec­tion. Vibra­tion sensors detect the reso­nances and make them inef­fec­tive. During the test start-up, the vibra­tion level is analyzed over the entire speed curve.

If exces­sive vibra­tion veloc­i­ties occur, the control soft­ware auto­mat­i­cally skips the crit­ical speed ranges during oper­a­tion. At the end, every­thing was a perfect fit. The fans were sealed on the side facing the existing wall. A tiny door allows access to the rear. “It’s very impres­sive how all the elec­trical connec­tions and cables inside are so precisely laid out,” says Peter Halblaub in awe. “We have been waiting for the first big test run for a long time.”

Clean solu­tion: even after ten months, the oper­a­tors could not find any signif­i­cant dirt parti­cles in the system during the check. (Foto: Tobias Gerber, Fotogloria)

Test run at full power

The big day finally arrived at the begin­ning of January. The system was ready to run at full power. Along­side Wolf­gang Stickel and Peter Halblaub, the ebm-papst engi­neers were also present. “It made a real whirring noise when all sixteen devices were running at full speed,” recalls Peter Halblaub. His enthu­siasm is evident as he continues: “The noise level is very low, even though there’s so much power behind it. Even when idle, the old machine was noisier. The Radi­Pacs run very quietly and highly effi­ciently.” And what about the wall? It was perfect: no reso­nance vibra­tions. In the venti­la­tion room, the project team was very satis­fied.

Another advan­tage of the FanGrid is the oper­a­tional reli­a­bility that comes with it. With the 16 fans, the system oper­ates with redun­dancy. As the system is slightly larger than neces­sary, even if one fan fails, the nominal oper­a­tion can be fully main­tained by adjusting the remaining 15 fans. This is of great signif­i­cance to the oper­ator, as in the event of a failure of the venti­la­tion system, there would be a risk of complaints, possibly even going as far as loss of rent.

“With the new solu­tion, we can choose speeds from zero to one hundred, moving along the char­ac­ter­istic curve as required.”

Wolf­gang Stickel, Building tech­ni­cian at Sauter FM GmbH

Ten months on from the big day, everyone is still satis­fied. “The system is still working perfectly. We have not had a single failure yet,” confirms Peter Halblaub. Control­ling the system using FanCon­trol has also proven a success. “The differ­ence is like night and day,” says Wolf­gang Stickel. “The old system only had two settings. With the new solu­tion, we can choose speeds from zero to one hundred, moving along the char­ac­ter­istic curve as required. The FanGrid achieves an air flow rate of just over 120,000 m³/h at a static pres­sure of 1,000 pascals. The system is oper­ated with pres­sure regu­la­tion, which is a highly state-of-the-art func­tion.”

Huge energy savings

The cutting-edge tech­nology of the system is also notice­able when it comes to energy effi­ciency. “We’re still making adjust­ments,” explains Peter Halblaub. “But we already know that we consume signif­i­cantly less elec­tricity. The savings come to almost 50 percent. We also check the system constantly for dirt parti­cles, but so far we haven’t found anything of note.” He is now certain that his deci­sion to install the FanGrid was the right one. So sure, in fact, that he is consid­ering a retrofit for another venti­la­tion system in Neckar­sulm. Investing in this kind of fan config­u­ra­tion in the shop­ping center has paid off.