Water-Source Heat Pump

What Is a Water-Source Heat Pump?

A water-source heat pump (WSHP) in HVAC uses the same technology as water-to-water heat pumps, but is smaller and meant for distributed systems. WSHPs are available in vertical, horizontal, console, and rooftop unit designs. They are engineered to deliver high energy efficiency, reducing energy consumption and lowering energy bills.

How Does a Water-Source Heat Pump Work?

A water-source heat pump operates by rejecting heat to a water loop during cooling mode or by absorbing heat from the same water loop during heating mode. Here's a look at the process in more detail:

1. Each zone has its own unit with a small, electric refrigeration system inside.
2. A building wide water loop circulates between all units.wide water loop circulates between all units.
3. In cooling mode, the unit transfers heat from the room into the water loop. In heating mode, it pulls heat from the water loop into the room.
4. Central equipment keeps the loop in a comfortable range (typically about 60–90°F):
   • If the loop gets too warm, a cooling tower or dry cooler dumps heat outdoors.
   • If the loop gets too cool, a boiler, heat exchanger, or heat recovery device adds heat. recovery device adds heat.
5. Because different spaces can be heating and cooling at the same time, heat is often “shared” across the loop, meaning waste heat from one area can warm another, reducing the need for the tower or boiler to run and improving energy efficiency.

Each WSHP unit is an independent, packaged system, which means all its components are in one convenient location. This design simplifies maintenance and allows for individual zone control, meaning different areas of a building can be heated or cooled simultaneously to meet specific needs.

Benefits of Water-Source Heat Pumps

There are several benefits to installing a WSHP system:

• Energy efficiency and lower operating cost: Heat pumps move heat instead of making it from scratch, so they use less energy than electric resistance or many gas systems, especially when zones exchange heat on the loop.
• Great for multizone buildings: Each tenant/room gets its own thermostat and unit. Heating and cooling can happen simultaneously in different areas without conflict.
• Scalable and flexible: Easy to add, relocate, or replace individual units as tenants change; useful for offices, schools, hotels, senior living, and mixeduse.
• Heat recovery: Internal heat from sunny façades, data closets, or kitchens can be repurposed to heat perimeter or morningstart spaces.
• Comfort and acoustics: Short duct runs and local control typically mean faster response and quiet operation.
• Redundancy and serviceability: If one unit is down, only that zone is affected. Most work happens inzone without shutting the whole building.
• Electrification pathway: Water-source heat pumps are electric. Pairing with heatrecovery chillers, geothermal fields, or lowcarbon power helps reduce onsite combustion and emissions.
• Space efficiency: Smaller rooftop impact than many packaged rooftop units; piping is often easier to route than large ducts

Resources for Water-Source Heat Pumps:

• Trane Water-source Heat Pumps
• Systems Using Thermafit™ (MWS) Water-Source Multi-Pipe Technology

To learn more about Trane's water-source heat pumps and determine which is right for your building, contact your local Trane representative.