Heat Pump

What Is a Heat Pump?

A commercial heat pump is a mechanical system that transfers heat from one place to another using a refrigeration cycle. In winter, it moves heat from outdoor ambient air, indoor air, thermal energy storage, or the ground (as in geothermal storage) into the building. In summer, it reverses to move indoor heat outside (cooling). They are used in split systems, packaged rooftop units (RTUs), chillers, and variable‑refrigerant flow (VRF) systems in commercial buildings.

How Does a Heat Pump Work?

A heat pump uses a refrigerant that circulates between an evaporator and a condenser, creating a continuous cycle of evaporation and condensation to transfer heat. When it has a reversing valve within the unit, the evaporator and condenser can change roles, switching between heating and cooling.

Types of Heat Pumps

Several types of commercial heat pumps are available.

• Air-to-water heat pumps: Also known as heat pump chillers and reversible heat pumps, these use a reversing valve. As a two-pipe unit, they can heat and cool, but not simultaneously.
• Water-to-water heat pumps: Also known as heat recovery units and non-reversible heat pumps, with this proven technology, heating is a byproduct of cooling load.
• Water-source heat pumps (WSHP): These use the same technology as water-to-water heat pumps, but are smaller equipment for distributed systems. They can also be used in geothermal systems.  
• Multi-pipe units: These can include four or six pipes and can heat or cool, or simultaneously heat and cool. Four-pipe units are air-to-water, and six-pipe units are water-to-water.
• Geothermal heat pumps: These are six-pipe units that use a body of water or the ground as their heat source. 
• Hydronic heat pumps: Any water-to-water heat pump that's part of a hydronic system. 
• Rooftop heat pumps: Packaged rooftop units that use electricity.
• Dual-fuel heat pumps: Rooftop units that use electricity and gas. 
• Variable refrigerant flow (VRF) heat pumps: VRF units send refrigerant from an outdoor unit to multiple indoor units. They can heat or cool, but not both at the same time.
• Hybrid VRF (HVRF): These are like VRF systems, but part of the system is hydronic, and the other part uses refrigerant. HVRF is good for sensitive applications where it would be challenging to evacuate in case of a refrigerant leak.
• Domestic hot water heat pumps: These are available in air-sourced and water-sourced versions and provide hot water for laundry, hand-washing, etc. 

Resources for Heat Pumps:

• All-electric or hybrid heat pumps for higher-efficiency heating and cooling
• The Future of Heating Equipment is Electric: Heat Pump Technology Deep Dive
• Myth versus Fact: Understanding the Value of Heat Pumps
• Scope 1 Emissions Reduction: Why All Eyes Are On Heat Pump Technology
• Case study: Heat Recovery System Makes Impact
• Case study: Heat Recovery at Science Museum of Minnesota: Reducing Costs and Carbon Footprint
• Case study: Retrofit Creates Sustainable Building Model

Switching to a heat pump system from a fossil-fuel-based system can be a significant step toward decarbonization and achieving sustainability goals. Talk to your local Trane representative to determine the best path forward for your organization.