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Quebec Natatorium Uses Geothermal, Reduced Refrigerant HVAC, Heat Recovery

May 9, 2013 By Linda Hardesty

Tpoolhe new $18 million, 45,000-sq-foot Aquatic and Community Centre in Côte Saint-Luc, Quebec, employs a 500-ft-deep geothermal field, exhaust air heat recovery for preheating outside air, dehumidifier compressor heat recovery for free pool water heating, and a reduced refrigerant HVAC dehumidifier strategy.

The city will achieve a four-year payback, save millions of dollars in energy costs over the lifespan of the facility and minimize the local environment’s exposure to refrigerants.

The HVAC technology making the project’s most environmental impact is the energy recovery dehumidifiers from the new Protocol NP-Series by Seresco, which use up to 80-percent less refrigerant than comparably-sized conventional mechanical natatorium dehumidifiers, while delivering an annualized operating cost reduction of five to seven-percent. Instead of an all-refrigerant design, the dehumidifiers use heat exchangers and glycol for heat rejection to the water-source loop.

Pool water heating is supplied by a coaxial-type heat exchanger using recovered waste heat from the two Seresco dehumidifiers’ refrigeration circuits, which are required for dehumidifying the space to a 55-percent relative humidity.

If pool water heating is satisfied, the remaining heat is rejected to the geothermal water source loop or into supply air for reheat. On subzero days when pool water heating isn’t 100-percent satisfied by heat recovery, the 96-percent efficient back-up condensing boilers by Camus Hydronics Unlimited are activated.

Throughout the summer months, heat rejected to the water source loop is stored in the six-well, 500-ft-deep geothermal field for use later in the heating season. The water source loop, which averages temperatures over 80°F in the summer and provides almost all the heating for domestic hot water and locker room showers, also uses two rooftop evaporative cooling towers by Baltimore Aircoil to reject any excess heat not required within the complex.

The geothermal loop’s operational and redundant 20-hp pumps by Taco use Danfoss variable frequency drives (VFDs) to operate at only the needed flows. For example, when heat pumps or the dehumidifiers are not requiring cooling or heating, the VFD’s ramp down the pumps’ water flow for further energy savings.

All systems are monitored and controlled by a BACnet-based building automation system by Automated Logic.



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