Tri-County Electric, a rural Minnesota electric cooperative investigated the 144,000 square foot Caledonia High School, in Caledonia, Minnesota, for energy saving opportunities in response to the District’s concerns regarding energy costs and a pending rate increase. The facility was approximately 4 years old and includes a ground source heat pump system. Tri-County identified potential savings with the water circulating system and referred the District to Michaels for further assistance.
Michaels conducted a walk-through investigation to identify potential opportunities and gather information for proposing the next steps. The pumping system indeed provided opportunity, but so did makeup air units, and ventilation controls. Michaels conducted the feasibility study and developed three primary energy saving measures:
Convert the primary/secondary pumping system, a parallel pumping system, to series only. This included removing one 100 hp circulating pump that operated at 60Hz altogether, installing isolation valves on heat pumps and interlocking them with the heat pump compressors, and controlling the remaining pump with circulating loop static pressure.