Whisperpack® Water Source Heat Pumps – Overview

Whisperpack vertical stack fan coil heat pump mainIf you're looking for a unit that provides the reliable air conditioning of a water source heat pump with the near-silent heating of a fan coil, the Whisperpack® from Whalen delivers the best of both worlds.

Combining the best characteristics of our field-proven compressorized and fan coil products, we’ve developed a unit that delivers superior air conditioning performance along with the operational characteristics found in our powerfully productive fan coil units.

Whisperpack® units benefit owners during the heating season through the use of a hydronic heating coil in lieu of reversing the refrigerant cycle. This allows for energy savings by turning the compressor off and diverting the condenser water to a heating coil.


  • Benefits
  • How It Works
  • Technical Data
  • Literature

True to our commitment to offer equipment that’s flexible enough to meet the design of the building rather than forcing a building to conform to limitations of the equipment, our Whisperpack® Air Conditioners with Hydronic Heating can be applied to any type of building.

They’re particularly advantageous for new construction or renovation of apartments, condominiums, hotels, senior living facilities, dormitories and office buildings.  This philosophy behind Whisperpack® units isn’t limited to physical size or optional accessories, either.  They’re capable of performing at peak operating efficiency at entering water temperatures between 85°F and 120°F.

Easy to Install and Service

By utilize a single set of risers, Whisperpack® units are able to stack from floor to floor, thereby simplifying the installation.  For staged installation projects, cabinets can be shipped separately from the refrigerant chassis.

The chassis, which includes the complete refrigerant circuit, slides into the cabinet after the construction debris has been removed to ensure trouble-free operation at start-up. 

When a chassis requires service, it can be quickly replaced in a matter of minutes by sliding the existing chassis out and sliding a spare chassis into the cabinet.

Efficient and Environmentally Friendly

With efficiencies up to 15.7 EER, Whisperpack® units are both environmentally and economically friendly.  Operating well above the ASHRAE 90.1 minimum, these units exceed minimum thresholds for most utility rebate and incentive programs.  All units run on Ozone-friendly R-410A refrigerant.

Small in Size … Quiet in Operation

Since we offer one of the smallest footprints in the industry along with customization capabilities including cabinet height, riser locations, handing and discharge arrangements and sizes, your new Whisperpack® units will be installed and operating in significantly less time.

Dual-level vibration isolators are integrated into every unit to help minimize vibration and noise transmission.  An acoustically insulated compressor enclosure further reduces any sound transmission, making these units ideal for noise-sensitive applications.

Supply Opening

Left, Right, Front, Back and Top Combinations – all supply openings are painted black to block the view into the unit.  When one unit is used for two rooms, a sight baffle is placed between the two grilles.

Supply Grille

Aluminum construction minimizes future maintenance and eliminates oxidation that can be caused from condensation. 

Supply grilles are offered in single or double deflection, with or without an opposed blade damper.

Supply/Return Risers

These are provided to meet the requirements of the job site.  Custom lengths can be provided to meet the exact floor-to-floor dimension of the project.

Risers are factory-installed and piped to ball valves within the cabinet, or they can be shipped separately to the job site.

Riser Cover

A galvanized steel protective cover is standard to avoid riser damage during shipping, handling and installation.

Control Valves

A 3-way control valve is standard on every Whisperpack® unit.  For added flexibility, we offer an option for two 2-way valves for use with variable speed pump systems.

Ball Valves

Shutoff valves with hose bib (GHT) connection are standard on every unit.

Fan/Motor Assembly

Plug-in type fan/motor assemblies are easily removed through the return air opening.


All units are available with glass fiber high density insulation, with thermal and acoustical properties.  


Single-piece galvanized monocoque construction with a snap-lock front panel prevents air leakage through cabinet seams to increase efficiency.

Refrigeration Chassis

The removable chassis is a floating design with insulated compressor compartment and vibration isolation.

Hydronic Heating Coil

For heating, a 2-row or 3-row integral water heating coil utilizes the hot water supply piping in the building to eliminate the need to operate the compressor when heat is needed.

Water Hoses

Stainless steel braided hoses connect the chassis to the supply and return water piping, while isolating the compressor vibration from the building's piping system.

Inner Service Panel

Removable for access to unit control wiring and internal piping.


Filters are available in "throwaway" and permanent options.

Drain Pan

The drain pain covers the entire unit bottom.  


Several thermostat options are available in the following configurations:

  • Low voltage
  • Plug-in or remote mounted
  • Manual or automatic changeover
  • Electro-mechanical or electronic

Acoustical Panel

Standard and flush-mounted designs feature a hinged door to allow for filter removal – without the use of tools.

Return Air Grille

The aluminum grille comes with standard or removable core capabilities.

Unit Tagging

Each Whisperpack® unit from Whalen is individually boxed and tagged with factory and customer-supplied information.  Each unit can be tagged with specific room numbers, riser numbers or any other special requirements of the project.

AHRI Certified

AHRI Certified Water Source Heat Pump


Heating Mode

In the heating mode, warm condenser water is diverted through the hydronic coil via a 2-way control valve. The air coil supplies warm air to the conditioned space. The 2-way valve that allows water to flow to the refrigerant-to-water heat exchanger is in the closed position. (See Figure 1 below)

Whisperpack vertical stack fan coil 03 heating

Cooling Mode

In the cooling mode, cold refrigerant flows through the air coil. The heat pump supplies cool air to the conditioned space. The heat removed from the room air is transferred to the refrigerant flowing through the refrigerant coil. (See Figure 2 below.)

Whisperpack vertical stack fan coil 03 cooling

Whisperpack® Water Source Heat Pump

WhisperPack Water Source Heat Pump Technical Data