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Drying expertise with Bitzer intelligence

With a population of 1,800, the city of Stiefenhofen is located in the centre of the Allgäu region, surrounded by lush green meadows and hills. So lush, in fact, that you may find it hard to believe that the one company in the city specialises in drying. Based here, Harter GmbH manufactures drying systems for industry, focusing on condensation drying based on heat pumps. An integral part of these heat pumps: Bitzer compressors and IQ modules.

People flock to the idyllic Allgäu region from near and far for a bit of relaxation. Stiefenhofen is also one of those resort towns that fill holidaymakers with a feeling of bliss. But those whose profession has led them here are also lucky: a variety of industries, including clocks, jewellery, automotive, pharmaceuticals, food and surface technology, all place their trust in the systems supplied by the family-run company Harter when it comes to drying their industrial goods, sludges and foods.

That’s no surprise to Reinhold Specht, managing director of Harter: 'We’re always doing new things, which makes us who we are. Satisfied customers and durable systems with lasting value have been our aim from the very beginning. We got started in 1991 and one of our systems from 1992 is still in operation today.'

Harter manufactures around 50 systems of all sizes and for a whole host of applications every year. With its method of drying, the manufacturer of specialist systems makes a key contribution to environmental protection and sustainability – one of the reasons Harter works with Bitzer components. The two companies pursue the same philosophy: high-quality, energy-efficient products. And reliability: 'Our systems are always running, day and night,' explains Mr Specht. 'So we can’t allow for any downtime. If I sell a machine to a renowned company today and, after two or three years, the compressor breaks down – that just won’t do. That only causes problems and, of course, rules out any future business, which is why we switched entirely to Bitzer in January 2018.' 

But the drying business isn’t that simple: 'Every customer requires something different,' Mr Specht continues. 'Every sector has its own peculiarities and each application is a new task. The aggressive air in electroplating, for instance, is a challenge. Other customers, on the other hand, including those in the sludge-drying industry, pay close attention to how much water is extracted.' 

Companies dry sludge in order to reduce its mass and thus disposal costs. Lots of water is extracted at the beginning of the drying process, and then less and less thereafter – a good example of just how important well-functioning capacity control is, as Mr Specht explains: 'If you maintain the same capacity for the entire process, you’re no longer working effectively. Frequency inverters don’t allow us to reduce capacity to the degree we would like. Bitzer Varistep mechanical capacity control provided us with virtually stepless capacity control for the first time. We can therefore adjust capacity in line with the drying goods. That’s the primary reason we opted for Bitzer IQ modules.'

Bitzer IQ modules are always used when system monitoring makes sense, there are cost and time pressures, or the Ecodesign Directive requirements need to be fulfilled. Much of that applies to Harter, which is why in many cases the family-run company now places its trust in Bitzer ’s modern operating concept for reducing system complexity and potential for errors. The IQ module allows Bitzer reciprocating compressors to be quickly, cost-effectively and easily integrated into any system. This way, even complicated errors can also be quickly and easily identified and rectified; at Harter since late 2016. 

'We tried out an IQ module with one of our Austrian customers in the surface technology sector for the first time and it’s going well. This customer is actually a prime example: we’d had to make frequent repairs to their system, so at some point we updated it with two Bitzer compressors. Everything has been fine ever since. The surface technology sector is basically our home, as that’s where we started out. But we’ve also used the modules, for instance, in the food industry, in the largest system we’ve ever built: mushroom drying in the Netherlands. The customer must have spent two years trying out different things before we realised that only the Harter drying system can preserve the pale colour of the mushrooms. No one wants brown dried mushrooms,' says Mr Specht laughing.

Harter has around 70 employees in Stiefenhofen, including ten refrigeration technicians such as master refrigeration technician Dennis Schiller, project manager and the driving force behind the use of the IQ module in Harter drying systems: 'It’s becoming more and more important for us to be able to control capacity. There are customers who say they want to be able to dry at 75 degrees and then lower it to 30. We need to be able to make that possible and that’s also our benefit with the IQ module. In the case of water extraction, for example, we realise that it’s no longer very effective for the compressor to operate in full-load. So we reduce it. If we can control the compressor, we can also reduce energy consumption and adapt it in line with the level of water extraction. If we were unable to control it, achieving good values would be difficult.'

Good values are everything at Harter – to a large degree, the company also survives from the energy efficiency of its systems. Harter plans just as effectively with all its resources: the company has a single programmer, who no longer has to write any programs for many systems because the IQ module is simple to operate. Employees in the field then work with the BEST Software and the BEST interface converter. 

'If there’s a fault of any kind, the customer can download Bitzer ’s BEST Software and connect it to the compressor, which allows us to locate the error. After all, our customers aren’t around the corner, but scattered all over the world. Before that, it was more difficult to determine and the conclusion was: the system doesn’t work. But now we can offer remote maintenance, which saves lots of time,' explains Mr Schiller.

Andreas Riesch, Bitzer Director of Sales for Germany and Switzerland, adds: 'IQ modules simplify system operation and maintenance. As well as system commissioning: we preconfigure and test the modules, including wiring and accessories, at our premises, reducing the work for our customers: comprehensive compressor control and monitoring are connected to the switch board via a single cable.'

It’s important to Harter to be able to offer its customers energy-efficient and eco-friendly solutions, as demonstrated, for instance, by its choice of refrigerant: R450A is standard at Harter. But: 'Because we also operate at extreme temperatures in some cases, we need to determine which refrigerant is suitable. A key benefit of Bitzer compressors is their large application range. That’s another reason we’ve now switched entirely. You never know what the future holds. But with Bitzer , we know that if there are another five new refrigerants in five years, we can use them in our Bitzer compressor. And it will run. That’s a huge benefit,' explains Mr Schiller.

'Customers also opt for us because we manufacture energy-efficient systems,' adds Mr Specht. For them, the company based in the Allgäu region reduces energy consumption by up to 75 per cent in the drying process – thanks also to Bitzer . Harter has already manufactured 20 to 25 systems with 30 to 40 compressors featuring IQ modules. Harter also uses the compressor specialist’s liquid receivers, not to mention the Rotalock valves of AWA, a Bitzer subsidiary. AWA itself uses a Harter drying system, whilst the Bitzer paint shop in Rottenburg-Ergenzingen houses three Harter drying systems. Life is simply about giving and taking – including at Harter in the breathtaking Allgäu region.


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