Functionality, reliability and simple execution for the revamping of the thermal power plant

The situation

Located in the centre of Selva di Val Gardena and surrounded by the majestic scenery of the Dolomites, the Residence Hotel Antares offers its guests a unique alpine experience where customers can discover relaxation and comfort.

In addition to the main hotel building – a 50-room hotel that accommodates 100 beds and exclusive services such as a swimming pool, sauna and wellness centre – the complex also includes two nearby serviced apartment blocks for tourists, which contain 60 rooms and space for up to 150 beds. Over the years, the hotel has been constantly modernised and recently, in order to save energy and improve energy efficiency, the owner – the Residencehotels SpA family group – decided to renovate the HVAC system that was previously managed by separate boilers.

“The need arose to unify the setup and update the HVAC system”, says Technical Director Diego Pozzatti, at Cos.mo. SpA, “the aim was to achieve an overall improvement in the system’s performance, and be able to control and manage the heating throughout the hotel”.

The solution

The heating system was renovated by opting for an internal district heating system and centralising the boiler system, which currently supplies heat to several exchangers with substations located within the three separate facilities (the hotel and the two adjacent serviced apartment blocks). Specifically, 35 Grundfos MAGNA3, MAGNA1 and ALPHA2 wet rotor circulator pumps were installed, which send the carrier fluid from the boiler room to the substations at the individual facilities to ensure a continuous high-efficiency service, as well as eight innovative MIXIT mixing loops. “The MAGNA3 D pumps installed in the HVAC system enable the hot water to circulate to the exchanger and feeds both the heating circuit and the domestic hot water circuit. Then there are other pumps installed directly on the heating circuit”, clarifies Diego Pozzatti. “The advantage they have is the fact that they are electronically controllable variable speed pumps, easy to monitor and able to ensure flow rates that can be adjusted in relation to demand and the number of people in the hotel. Meanwhile, the MIXIT mixing loop features a pump that already connects directly with the mixing valve within a unique circuit, which can measure a whole range of very important data in terms of hotel management in an integrated way, such as consumption parameters. You therefore benefit from a mixing valve and a pump installed within the same group, saving space and assembly time.” MIXIT is an all-in-one mixing loop, equipped with flexible features and functionality designed to meet the various needs of heating and cooling systems.

IThe result

For two years now, the installed pumps and MIXIT loops have been managing the heating and domestic water for 67 apartments and 43 hotel rooms – for over 100 lodgings in total – without any problems or service interruptions. Thanks to a dedicated Building Management System, which enables the system to be monitored remotely, the system’s various parameters can also be monitored remotely, allowing any prompt intervention as required. “On many occasions we happened to notice a problem, and within an hour we were able to fit everything back together”, confirms designer Ruggero Celva. “This is the great advantage of remote monitoring. Once trained, the internal maintenance technicians can also check on the system parameters two or three times a day through a web server or any application that has a web browser, without having to physically go and look at the HVAC system, all thanks to a summary screen where the boiler and domestic water temperatures and the status of the pumps can be observed, with any anomalies highlighted.” The Technical Director points out that Cos.mo SpA has supplied Grundfos devices for several years now, welcoming their efficiency and the huge reliability they guarantee. “We have already noticed big savings in terms of consumption”, Pozzatti continues, “although currently we still can’t quantify this precisely, mainly because of the various systems already present in the building, which are not comparable with the current ones. The savings are clear, thanks to the optimal operation of the boilers in a single integrated system and the lower electricity consumption of the current pumps, with variable frequency. We are storing all the useful data for any future comparisons”.

The testimony

"We’ve been working for Residencehotels for years and share a long-standing relationship of mutual trust. The owner’s requirement was to revamp the HVAC system of the Residence Hotel Antares, covering several buildings, along with the modification of the traditional domestic water storage systems. In fact, due to the issue related to Legionnaires' disease, for some years we proposed that Residencehotels replace the traditional storage tanks with drinking water storage devices combined with a heat exchanger. This means that cold water would come from the water mains at 10 °C, therefore free of contamination from legionella (a bacterium that proliferates between 25 and 45 °C), and that, through a system of exchangers, hot water would be produced at 60 °C in real time and according to requirements. Combining these needs, it was decided to revamp the building’s heat generation system, opting for a small internal district heating system and centralising the boiler system. We chose Grundfos devices because, based on the experience we’ve gained over the years across several professional facilities (hospitals, tourism, manufacturing, industry, etc.), this company has always guaranteed us the benefit of using reliable, high-performance products. These fundamental characteristics ensure the continuity of system operations, as well as an uninterrupted domestic hot water and heating service. We weren’t familiar with MIXIT. It was the first time we included this product in a project and tested it on the field, but we went ahead with it based on trust, thinking "if Grundfos has taken this path, this is definitely a product that guarantees a performance standard up to the level of reliability we’re looking for”.

“And we weren’t wrong. Taken on over several seasons during breaks when the facilities were closed, the project was very complicated to carry out and required a significant commitment in terms of time and investment. But Grundfos was always right on hand to provide information, including via a specialised channel dedicated to any technical aspects. The company has trained persons who are specialised in certain products: this is a rare thing and very much appreciated.”

The testimony

“I believe that this installation, also thanks to the choice of MIXIT mixing loops, was easier than those we usually handle, because there were fewer components to deal with and they were also already pre-assembled in the factory. Commissioning was really quick: it was easy and intuitive for technicians to understand the operations to be carried out. We opted for this solution to have on-board adjustment and the integrated energy meter, even if it doesn’t have MID certification. These devices ensure that operation is guaranteed and completely autonomous, which is a significant advantage. In our Group, work teams are always composed of two people and the assembly time obviously depends on the size of the systems. However, in this case I would say that it took us from two to three hours to install the larger devices, but in some cases it was difficult to maintain the minimum distance of half a metre between the pump and the MIXIT loop. So, while I would make the same choices again for new systems, especially large ones, I would also increase the maximum distance between the MIXIT loop and the circulator. Any suggestions? For systems like these, it would be better to have clean heating water. We always had to rinse the system, which in any case would have been necessary regardless of whether or not a MIXIT loop was used.”