Can commercial heat pumps be used for domestic hot water?

[David Busker]

Yes, commercial heat pumps can be used to heat domestic hot water, often requiring a large storage tank to compensate for the heat pump's inability to provide hot water on demand. These systems offer climate-friendly, energy-efficient, and cost-saving benefits, especially in larger homes or buildings with high hot water needs. However, a supplementary heating source might be necessary to reach the 60°C (140°F) temperature required to prevent Legionella bacteria growth.

How Commercial Heat Pumps Heat Water

• Heat Transfer:
  Like a regular boiler, a heat pump transfers heat from a source (air, ground, or water) to the water, which is then stored in a cylinder.
• Higher Capacity:
  Commercial units are designed for high demand, providing faster hot water recovery and serving large homes or multiple dwelling units.
• Integration:
  They can be integrated with building management systems for optimal performance and can work in combination with space heating.

Key Considerations

• Storage Tanks:
  Because heat pumps extract and deliver heat over time, a storage tank is essential for storing heated water to meet demand.
• Legionella Prevention:
  Some heat pumps may need a secondary heating system, such as immersion heaters or a backup boiler, to reach and maintain the 60°C (140°F) temperature needed to kill Legionella bacteria.
• Bivalent Systems:
  To ensure efficient operation, especially in colder climates, a bivalent (hybrid) system may be used where the heat pump handles most of the load and a secondary source provides the boost when needed.
• System Sizing:
  Commercial systems are defined by their size (e.g., input power of 6 kW or more, or water storage of 120 gallons or more), not just the load they serve.

Benefits

• Energy Efficiency:
  Heat pumps are an energy-efficient alternative to fossil fuel heating, significantly reducing energy consumption.
• Environmental Impact:
  They help in building electrification and offer a greener path to hot water by moving heat rather than burning fuel.
• Cost Savings:
  Improved technology and potential for integration with grid-responsive controls can lead to lower operational costs.