Project Snapshot: Freetown Lakeville Intermediate School | Pool Unit

Project Name: Freetown-Lakeville Intermediate School
 Architect: Architectural Resources Cambridge, Inc.
Mechanical Engineer: SED Associates
Mechanical Contractor: Ambient Temperature, Inc..
Equipment: Pool Dehumidifier
Manufacturer: Seresco
Size: Seresco NP-18 Pool Dehumidification Unit.
DAC Sales Engineer: Craig Ashman

Project Overview:

In 1994, Rick McGinley from DAC Sales designed an air-to-air dehumidification unit for the George R. Austin Intermediate School (Freetown-Lakeville Intermediate School).  The unit was supplied by Des Champs and was state of the art, for the time.  It utilized two air-to-air plate exchangers, a modulating re-circulation, and outside air dampers to regulate the outside air volume to the precise amount required for humidity control. This unit conveniently provided minimum outside air flow at the time when heating costs would be highest. Code ventilation rates were still maintained with a minimum set point on the dampers.


In 2016 Craig Ashman, DAC Sales Engineer, was contacted by SED Associates of Boston to discuss the replacement of this original unit.  The replacement would have to be accomplished with minimal disruption to existing structure and operations.  If possible, existing duct work and roof curbs were considered to make the transition smoother.


It was determined that the most cost effective piece of equipment, both first cost and operating cost, was the Seresco 18 ton Protocol Series unit.  A custom roof curb adapter was also designed and furnished to accommodate unit mounting.

Roof Curb Adapter

Glycol Cooled A/C by a Fluid Cooler–  About 40% of the units Seresco provides use fluid coolers in lieu of Refrigerant Based ACCU’s.  This is a standard product offering in their Protocol Line of Pool Dehumidification Units.  In the Pool Dehumidification Unit, Seresco provides a heat exchanger and a pumping package. In the heat exchanger, the refrigerant loop dumps the rejected heat to a glycol loop. It is then pumped to the Fluid Cooler on the roof. Piping is PVC from the Pool Dehumidification Unit to the Fluid Cooler. The Fluid Cooler distance can be nearly anything (600 feet is not a problem).

WebSentry –  This application was also equipped with WebSentry, Seresco’s online monitoring, reporting and service optimization tool.  The 24-7 WebSentry monitoring then allows Seresco to remotely monitor over 100 performance parameters of the dehumidifier using sophisticated algorithms to analyze and identify potential issues and maintenance requirements long before they become potential problems.

Design Advantages: There are many reasons why this type of application makes a lot of sense.  The ultimate is stable indoor air conditions through fully modulating reheat.

    • Up to 85% less refrigerant charge – completely factory sealed
      – Compliant with ASHRAE Standards 15 and 34
      – Less refrigerant means LEEDS points
      – Less cost to install and maintain
    • Eliminates all seasonal refrigeration and oil migration issues to outdoor condenser
      – Decreased risk of compressor issues
      – Increased performance
      – Lower maintenance costs
    • Air cooled AC heat exchanger can be located far from unit
      – Heat exchanger uses PVC instead of copper
      – Simple installation with lower cost of materials and labour
    • 5% to 7% more energy efficient than DX systems
    • WebSentry® Internet monitoring and control
    • Touch screen CommandCenter® control systems
    • Premium corrosion resistance
    • Mechanical vestibule outside the air stream on all units
      – more efficient operation
      – easy to service
      – protects key components from moisture and chemicals in the air stream

    To check for updates on the GRAIS pool, visit the district website at

For More Information - askRick




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