MODULE 3. System Design and Integration

The previous modules focused on the internal operation of heat pumps: their thermodynamic cycle and key components. In this module, the perspective changes. The heat pump is treated not as an isolated machine but as a piece of equipment that must be integrated into a building’s HVAC system. The goal is to understand how the unit behaves once it is connected to emitters, storage, controls, and other energy sources.

We begin by examining the performance of heat pumps under real operating conditions and the constraints that govern their behaviour (Lesson 14). This includes the impact of outdoor temperature, supply temperature, part-load operation, defrost cycles, and the operating envelope defined by the manufacturer. These aspects are linked to instantaneous and seasonal performance metrics, which are essential for correct sizing and for anticipating how the heat pump will perform throughout the heating and cooling seasons.

The module then turns to the systems the heat pump must serve: space conditioning (Lesson 15) and domestic hot water (Lesson 16). We analyse the typical emitters used with heat pumps (radiators, underfloor heating, fan coils and similar units) and how their temperature requirements are very important when using heat pumps. For domestic hot water, we review layouts, storage concepts, sizing rules, and operational constraints such as stratification and Legionella control.

Because hydronic heat pumps are the most common technology in boiler replacement projects, particular attention is given to water-based systems. In Lesson 17 we study the hydraulic components that must be added or adapted to ensure correct operation: buffer tanks, distribution pumps, bypass valves, hydraulic separators, diverter valves, antifreeze protection and other elements that stabilise flow, temperature, and system pressure. Building on this, Lesson 18 presents typical schemes that combine heat pumps, emitters, storage tanks, and auxiliary systems in practical residential and small commercial installations.

Once the basic schemes are understood, the focus shifts to design and control. Lesson 19 introduces heating and cooling load estimation, define peak and seasonal demand, and show how these link to heat pump sizing in different building conditions. Then, in Lesson 20 we review control strategies that connect heat pump output with building demand, including weather-compensated control, time schedules, smart thermostats, sensor placement and the main control sequences for temperature and flow regulation.

Finally, the module addresses integration with other renewable sources (Lesson 21). We examine how heat pumps interact with photovoltaic and solar thermal systems, how surplus PV electricity can be used to support operation, and how combined systems share the production of domestic hot water. The module concludes with an introduction to geothermal heat pump systems (Lesson 22), their main collector types, installation aspects, and the operational issues that affect long-term performance.

Together, these topics provide a complete view of how heat pumps are designed, integrated and operated within real building systems.