The Next Generation of Chiller Replacements: Transitioning to Air-Source Heat Pumps

The shift toward energy-efficient and low-carbon HVAC solutions is accelerating as regulatory requirements tighten and building owners seek to reduce their carbon footprints. HTS is addressing this change in the industry by promoting the replacement of a typical air-source chiller and hot water boiler system with Air-Source Heat Pump machines. These machines offer the end user the flexibility to tailor the usage of their Air-Source Heat Pump system to meet the building's operational goals.

The Limitations of Air-Source Chillers

Air-source chiller and boiler systems have been common practice in the HVAC industry over recent decades, and as a result, many existing buildings have been designed with such equipment. However, these systems face limitations that hinder their ability to meet today's sustainability goals:

• Single-Function Operation: Air-source chillers are designed solely for cooling, requiring separate heating equipment such as boilers or electric resistance heaters for year-round comfort.
• Refrigerant Concerns: Many older chiller models rely on refrigerants with high global warming potential (GWP), which are being phased out under environmental regulations.

The Case for Air-Source Heat Pumps

Air-source heat pumps present a viable alternative by combining heating and cooling capabilities within a single machine. Unlike traditional chillers, which rely on separate equipment for heating, heat pumps can reverse the refrigeration cycle via a reversing valve and reject heat to the building or ambient air, depending on the seasonal demand.

Key Advantages of Air-Source Heat Pumps:

• Reduced Usage of Secondary Heating Equipment: Air-source heat pumps can meet building heating loads in the winter, significantly reducing the use of boilers to solely serve as a backup source of heat at design conditions or as a supplemental form of heat to help achieve high supply water temperatures.
• Lower Carbon Footprint: Considering the approaches above, building owners can reduce their carbon footprint by minimizing the run hours on their boiler, but they can also consider the carbon footprint produced by generating electricity to power the building's heat pump. The end user's flexibility to switch use between machines leads to even further carbon footprint reduction.
• Reduce Energy Cost: Similar to the above, the end user has the capability to tailor the equipment used in an air-source heat pump system to reduce energy costs.

Transitioning from Chillers to Heat Pumps

Upgrading from an air-source chiller to an air-source heat pump requires careful planning to ensure compatibility with existing infrastructure. Key considerations include:

• Capacity Matching: The heat pump must be appropriately sized to meet both cooling and heating demands without excessive cycling or inefficiencies.
• Distribution System Adaptation: If the building was originally designed for chiller-based cooling and boiler-based heating, modifications to distribution systems may be necessary. These could include additional piping, piping componentry, pumps, and means of freeze protection, among other considerations.
• Control System Integration: Advanced control strategies will allow different machines to communicate through a building management system to meet the building's demands in the most energy-efficient and cost-effective manner. Integrating controls allows the end user to customize their system operation depending on building goals and best achieve the benefits of an Air Source Heat Pump system.

Government policies and incentive programs are accelerating the adoption of air-source heat pumps. Many jurisdictions are implementing building performance standards that require reductions in carbon emissions—financial incentives, including utility rebates, further support the business case for heat pump retrofits.

Conclusion

Replacing air-source chillers with air-so heat pumps is a forward-thinking strategy for building owners seeking to improve energy efficiency, reduce emissions, and adhere to the HVAC industry's changing design requirements. With advancements in heat pump technology and supportive policy measures, this transition represents a significant step toward a more sustainable built environment. Implementing these upgrades will ensure that buildings can achieve both comfort and compliance while embracing the next generation of HVAC solutions.