Custom VRF Handling Unit Conversion

Jersey Shore School District modifies (2) large air handling units to utilize VRF heat pump technology as part of comprehensive design-build ESCO project

HRG served as the MEP engineer-of-record, energy consultant and provided system commissioning.

The site was using (2) 25,000 CFM hot water / chilled water air handling units to condition their gymnasium.  The existing unit was unable to properly maintain conditions for several reasons, primarily driven by poor performance of a water-to-water heat geothermal heat pump and malfunctioning heat recovery wheels.

The school wanted to modify the unit to increase the total capacity of the system to match the needs of the space and improve the indoor environment by providing better control of temperature, relative humidity and overall indoor air quality.

HRG was the engineer of record and partnered with the ESCO to provide energy consulting and design services as part of a Guaranteed Energy Savings Project. HRG’s design responsibilities included Mechanical, Electrical, Plumbing, Fire Alarm and Fire Protection engineering (“MEPS”).  

The Air Handling Units were equipped with (2) sets of hydronic coils.  The first set of coils was a hot water coil fed from the existing hot water plant onsite.  The second coil was a dual-temperature coil that received both hot and chilled water (provided from a W2W geothermal heat pump) based on the demands of the space.  The unit was modified to remove the dual temperature coil and replace it with a new, multi-section VRF heating coil.  The VRF coils were sized to provide 100% of the heating and cooling load.  The units were also modified to include GPS Ionization Filters that were used to remove contaminants from the air (pre-Covid19) to allow for further reduction of outside air.

HRG’s Design Responsibilities Included:

  • Preparation of MEPS demolition drawings for the removal of the existing system components;
  • Review of the existing MEPS infrastructure present at the facility as required to support the addition of a new VRF Heat Pump system;
  • Preparation of MEPS design drawings for the proposed system including:
  • Installation of new AHU coils in existing air handling units.
  • Installation of roof-mounted VRF condensing units and associated refrigerant piping.
  • Development of AHU controls package and sequence of operations that was integrated into the site’s Building Automation System.

HRG’s Construction/Engineering Oversight Responsibilities Included:

  • Review of Contractor Shop Drawings;
  • Assist in responding to questions posed by the Contractors during the bid process;
  • Provide necessary engineering support, as required, to resolve technical issues in the field, and to clarify the intent of the engineering design and technical specifications;
  • Review and approve the appropriate information contained within requests for change orders and/or applications for payment;
  • Attending site meetings as required by the Client;
  • Served as the commissioning authority / third-party oversight to verifying overall function and performance of the system.

This project was successfully completed and put into operation in 2021.


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