When the time came to select the pumps for the Mall of Scandinavia, high operational reliability and superior efficiency were two of the key parameters. Around 200 Xylem in-line pumps are now helping to handle the supply of heating, cooling and domestic hot water to all areas of the giant installation.
Located in Stockholm, Solna, the Mall of Scandinavia is the biggest shopping centre in the Nordic region. It covers an area of 101,048 m2 and comprises of 224 shops and restaurants. Officially opened in November 2015, Mall of Scandinavia is the first shopping centre in Sweden to have been certified according to the BREEAM (Building Research Establishment Environmental Assessment Method, the world’s most used certification system for buildings) environmental certification system with a rating of “Excellent” during the design phase.
Approximately 200 pumps
The Mall of Scandinavia is heated and cooled using district heating and cooling from Norrenergi. The air in the ventilation system is either heated or cooled, depending on the outdoor temperature. The building is so large and complex that two plant rooms are needed to take water in and the heating or cooling is exchanged to the building system and circulated into the primary loop by pumps. The customer chose Xylem’s pumps for the entire indoor climate system of Mall of Scandinavia.
“In total, we supplied around 200 pumps to the site. These include both the main pumps for heating, cooling and domestic hot water, and the smaller circulation pumps in all mixing modules throughout the building,” explains Stefan Bergendahl, Sales Manager at Xylem, Stockholm.
Superior efficiency and greater operational reliability
Dry running rather than wet rotor circulation pumps were selected due to their superior efficiency and greater operational reliability. Pumps with dry motors can be incrementally more expensive to purchase, but their superior efficiency and – in particular – greater operational reliability in extensive systems make them more profitable in the long term.
“The main pump groups on both hot and cold sides consist of three pumps: two larger models that run alternately, and one smaller pump to cover low load periods. The largest and most important pumps on the cooling side are 37 kW Xylem in-line models,” says Ralf Lundqvist from the installer Sandbäckens Rör AB. He continues:
“The primary loops feature mixing modules that supply the ventilation batteries with water at the ideal temperature – thus ensuring that the air pumped into the building is also at the optimum temperature for the mall environment. Each ventilation battery covers a particular area of the facility. There are around 150 mixing modules in the entire building, and each module is fitted with a Xylem in-line pump.”
A mixing module is the link between a primary and secondary loop in a hydronic heating and cooling system. In the Mall of Scandinavia, they constitute the link between district heating/cooling and the hydronic ventilation system. The secondary loop often operates with other temperatures and flows than the primary loop. The mixing module is fitted between the two loops, mixing the media in a controlled manner to ensure that the correct temperature is achieved in the secondary loop. The circulation pumps ensure and maintain the correct flow in the secondary loop.
All pumps are controlled via the building’s control and monitoring system and the main pumps are revolution-managed to ensure the most economical operation.
“The working relationship between Xylem, the consultants and the installer has been excellent throughout the project. The installation and commissioning work ran smoothly as well, and we encountered surprisingly few challenges for an installation of this size,” concludes Bergendahl.