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Customer application 11 May 2022
RETROFITTING COMPLEX HVAC SOLUTIONS WITH WAGO

How do you install a new absorptions chiller, including peripherals, in a shipping container for use in an existing building? With the right partner for systems and building technology and the right automation solution. CHRISTOFFERS from Delmenhorst (Lower Saxony) and WAGO from Minden (North Rhine-Westphalia) show how. From the frequency converters, to the heat exchanger, to the connection to the building control system – all the chiller automation runs via a PFC200. In this project, the WAGO I/O System 750 once again demonstrates its suitability for both series production and custom solutions.

Some things just take a lot of time – municipal bureaucracies, for example, as many a building owner in Germany can testify. In a construction project for a northern German university site, the red tape was slowing things down too much. To retrofit an existing building with a chiller, an annex was required to accommodate the new technology. Because there was no chance that the construction permit application would be processed and approved in the foreseeable future, the project required ingenuity – as well as an innovative partner with extensive expertise.

An Overview of the Project:

  • The challenge: to automate the control of the chiller and the peripherals of the container and connect them to the higher-level building control system

  • Openness plus a modular design: The WAGO I/O System 750 was the only automation system considered

  • Everything under control – with the PFC200 as the central control unit

  • All the applications were conveniently implemented in using function blocks based on CODESYS V3.

A Creative Custom Solution from Established Experts

Instead of building a brick-and-mortar equipment room, the university’s facility managers soon decided to use a shipping container. A “mobile” solution like this is still subject to numerous regulations, but the approval process is much simpler than for a permanent structure. “In contrast to a freely designed annex, the dimensions of a standard container are fixed,” says David Gellermann. The head of the electrical engineering department at CHRISTOFFERS Anlagentechnik und Gebäudetechnik, a building services engineering firm, was in charge of accommodating the customer’s complex 318 kW absorption chiller within the steel walls of the 8 by 40 foot container.

This HVAC specialist from Delmenhorst is very familiar with this type of custom project. CHRISTOFFERS has around 130 employees who are always available when complicated problems require specialized solutions, as was the case here. The actual setup of the chiller system only took about three to four weeks, once the system layout had been worked and the automation control cabinet designed. “Because the container is transportable, we were able to finish the majority of the work on the hydraulics, the pipes and conduits and the electrical engineering at our headquarters. That meant that all we had to do on site was install the heat exchanger and complete the connection work,” says the electrical engineer, ticking off yet another benefit.

Multiple Subsystems, One Automation System

A total of four pumps are required to cool the existing building via the container. The first conveys the hot water, which is necessary for absorption, from the CHP at the nearby heating plant to the chiller. A second pumps cold water from the chiller to the heat exchanger, located on the container roof. The third pump connects the chiller to the university’s air-conditioning network. And finally, the fourth functions as a so-called free cooling pump, used whenever very low outdoor temperatures allow ambient air to be used for cooling via the heat exchanger and an additional unit. This achieves additional cost reductions, since the chiller can be temporarily powered down.

“Of courses, these four subsystems and their individual components were not provided by the same manufacturer,” explains Gellermann, pointing to one challenge in the system. “Our task was to link the chiller’s proprietary controller and all the container’s peripheral to the automation technology, as well as to connect that to the higher-level building control technology.” This required an automation system that is both open and modular – like the WAGO I/O System 750, which CHRISTOFFERS has routinely employed in its projects for years.

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A total of four pumps are required to cool the building via the container.

Uniform Communication between the Chiller and the Building Control Technology

A PFC200 forms the central control unit in the chiller container. A total of 15 I/O modules are connected in series to the controller, in order to link in the various digital and analog signals. On the input side, these include operating and fault notifications, supply and return temperatures and position feedback signals. The output side is primarily for control of the frequency converter, valves and shutoff flaps. The chiller and heat exchanger communicate with an additional serial interface module from the WAGO I/O System via Modbus RTU. The PFC200 (750-8212) has a factory-installed RS-232-/RS-484 interface and two ETHERNET connections on board. In this application, these are used to establish the Modbus TCP communication with the building control system and the connection to the WAGO Touch Panel 600.

Easy Automation Configuration with Ready-Made Libraries

The technical implementation of the WAGO automation solution uses . “Instead of using several individual programs for the design process, we can work much more efficiently using WAGO’s engineering software, because the entire portfolio is included in one state-of-the-art program in a very clearly organized way,” says David Gellermann. All the applications for the university were conveniently implemented in e!COCKPIT using function blocks based on CODESYS V3. This convenience stems primarily from the fact that WAGO provides ready-made HVAC libraries, which can be used to represent almost all typical tasks for heating, ventilation and air-conditioning in the building technology. “This made it easy for us to automate the chiller without problems in one go,” recalls Gellermann, who has worked at CHRISTOFFERS in Delmenhorst for more than seven years.

Customized Standard Solutions

The university’s chiller is a special solution, which has no counterpart in Germany – at least not yet. However, CHRISTOFFERS has already received initial inquiries about similar container solutions. David Gellermann and his team are well prepared, in part due to the flexible automation technology from Minden. “All the possibilities are open to us, both in the building and in the system design, because we can communicate using almost any fieldbus and transmit almost any signal. With the WAGO I/O System 750, we are able to accommodate any individual request in a standardized way.”

Contacts at WAGO

Andreas Henoch

Contact: info.projektplanung.de@wago.com

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