Community centre minimizes energy consumption with Grundfos MAGNA and VFD Kensington Community Centre and Pool, located in Vancouver, B.C., recently upgraded their existing heating system to run in an energy-efficient manner. The retrofit project replaces their previous system which had a constantflow secondary loop. The flow rates were established based on peak design condition, which represented only a small fraction of total operating hours. This constant-flow rate was maintained throughout the hydronic loop whenever the system was operating irrespective of demand, thus leading to energy wastage and higher operating costs. The consulting engineer faced the challenge of converting Kensington’s old heating system to a variable flow system. They needed to find the right pump and variable frequency drive (VFD) combination that would provide smooth operation of the system and yet be economical. The consulting engineer’s design retrofit project converted the constant flow secondary loop to variable flow by utilizing two valves. The new Grundfos system they recommended uses VFDdriven pumps that modulate speed based on the heating demand. The system consists of five MAGNA 65-120F inline wet-rotor pumps with integrated VFD. In the autumn of 2008, three of the
pumps were installed in the East Wing hydronic loop, and two in the West Wing. The MAGNA VFD system was chosen for the following reasons: (1) The pumping system has all the features required for the application, such as the compact design of the MAGNA and VFD combination with sensor-less pressure control capability. It also has the reputation of being reliable and requiring minimal maintenance. (2) The MAGNA pumps located in the East Wing are using a proportional pressure control method, where the differential pressure across the pump is automatically adjusted to match the flow demand of the system. In a closed-loop application, the main source of head in the system is the friction loss, which is dependant on the flow rate. As the flow rate increases, friction loss in the loop also increases and vice versa. The MAGNA pumps are intelligent enough to alter the differential pressure set-points based on the flow demand of the system, leading to reduced load on motor along with reduced energy consumption. (3) Grundfos has a unique AUTOADAPT control method that the pumps in the West Wing are using. In the
AUTOADAPT mode, the MAGNA attempts to learn the characteristics of the system and adapt itself based on this knowledge. This mode allows the MAGNA pumps to obtain an operating profile that is the function of the specific system into which it is installed. Since most system capacities are based on peak demand, using the AUTOADAPT shifts the proportional pressure control line to match the actual demand of the system. This leads to lower pump speeds and results in even greater energy savings. (4) The application can be continuously monitored by a direct digital control (DDC) system. A major advantage here was that the MAGNA pumps provided the desired functionality without additional sensors or inputs from the DDC, therefore making the system very simple and economical, with the ability to offer the right level of comfort and energy optimization. Vancouver Parks Service Department was also provided with a universal remote control that enables them access to all MAGNA and Grundfos “Eâ€? products internal programs. To this day, Kensington’s MAGNA VFD system is fully functioning to the satisfaction of the Vancouver Parks Board and the consulting engineer. Since the installation, the reduction of energy consumption and savings in operating costs is making it much easier for Kensington to better service their community. Grundfos is the world’s largest manufacturer of pumps and pumping systems. Grundfos’s Canadian headquarters are located in Oakville, Ontario. For further information please call 1-800-644-9599 or visit www.grundfos.ca. íľş
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Ops Talk • Fall 2011
