The Ultimate Guide to Heat Pumps


If you are a homeowner looking to upgrade your heating and cooling system or just looking for further knowledge, this guide is your go to resource for understanding, installing, and maintaining heat pumps.

Heat pumps have become significantly popular due to their energy-efficiency, their several environmental benefits, and their versatile heating and cooling capabilities. They are much more sustainable than the traditional HVAC systems as they harness renewable energy from the air, ground, and water.

In this guide we will investigate how they work, the different types, and how to maximise their efficiency. We will also help you to decide which heat pump is suitable for your specific needs, as well as how to size it properly and install it.

As efficiency is key, we will delve into performance metrics such as SEER, HSPF, and COP, to help you assess energy efficiency. We will also discuss cost savings, the reduction in your negative environmental impact, and potential financial incentives.

Browse the guide at your own pace or open the dropdown menu to click the links to jump to the sections you need the most.

Section 1 – What are Heat Pumps?

Heat pumps are a heating and cooling system that transfers heat from one location to another. They provide heating and cooling functions for residential applications. The pump works through a refrigeration cycle, that involves extracting heat energy from a low-temperature source (e.g., air, ground, or water), and transfers it to a higher temperature space (e.g., the inside of a building). The cycle can also be reversed to cool a space by removing heat from indoors to outdoors.

Heat pumps are energy efficient as they deliver more heat energy than the electrical energy they consume, allowing them to be a sustainable and eco-friendly solution for temperature control.

Comparison with traditional heating and cooling systems

Operation: Traditional heating systems, such as furnaces, boilers, and electric resistance heaters, generate heat through combustion or electricity resistance. Heat pumps, however, use heat from one location and transfer it to another using refrigeration technology.

Heating Efficiency: Many traditional systems are prone to energy loss during combustion or heat generation. Heat pumps transfer heat instead of generating it, resulting in higher efficiency and lower loss of energy.

Cooling Efficiency: Traditional systems used for cooling, include air conditioning units. Their energy efficiency is typically influenced by the technology used to create them or the age of the system. Heat pumps provide efficient cooling by reversing the cycle. Therefore, heating and cooling is carried out within a single system.

Energy Consumption: Traditional heating systems, mainly those that rely on combustion, tend to have higher energy consumption levels and operating costs due to energy loss during their process. By utilising an ambient heat source, heat pumps can reduce energy consumption, potentially achieving energy savings of 30% and reducing energy bills.

Environmental Impact: Traditional systems release greenhouse gas emissions through combustion, contributing to pollution and climate change. Heat pumps don’t rely on combustion and instead rely on a renewable heat source. Meaning they have a lower carbon footprint and significantly lower emissions.

Versatility: Traditional systems are either for heating or cooling, to have both, separate systems need to be installed. Heat pumps, however, offer both functions within one system, offering year-round temperature control, and providing convenience and flexibility.

Section 2 – Types of Heat Pumps

Air Source Heat Pumps (ASHP): This heating and cooling system harnesses the ambient heat from the air and transfers it to warm or cool a space. They provide cost-effective climate control, by moving heat between the outside air and inside. ASHPs can even extract heat in cold temperatures, so they are suitable within varying climates. They use electricity to move heat, not generate it, making them highly efficient. This also reduces costs and emissions.

Ground Source Heat Pumps (GSHP or Geothermal Heat Pumps): These pumps utilise the constant temperature of the earth to regulate an indoor temperature. GSHPs take heat from the ground in winter to transfer it indoors, and in summer the operation is reversed, as heat is taken from indoors and transferred to the earth. The system is facilitated by underground pipes (ground loops). Tapping into the earth’s renewable thermal energy makes GSHPs highly efficient, energy saving, and emission reducing. They can also create long-term cost benefits. They are versatile and can be installed in residential settings.

Water Source Heat Pumps (WSHP): These pumps use water as a heat exchange medium to regulate indoor temperatures. Heat energy is extracted from a water source (e.g., lakes, rivers, or wells) and transferred to an indoor space in winter months. In summer months the heat from inside is transferred to the water source. These pumps are more efficient as water has a higher heat capacity, and they also offer energy savings, reduced emissions, and are perfect for buildings near a water source.

Hybrid Heat Pumps: These pumps combine the benefits of multiple technologies to increase energy efficiency and performance. They usually integrate an ASHP with a traditional fossil fuel-based heating system. The system can switch between the two heat sources depending on external conditions and energy costs. The fossil fuel system is typically activated during extreme temperatures. Hybrid heat pumps can offer versatility and reduce energy bills.

Section 3 – How Heat Pumps Work

The refrigeration cycle and heat transfer

The refrigeration cycle is the process that allows heat pumps to transfer heat effectively and efficiently. There are four main stages of the process:

  1. Compression: A compressor increases the pressure and temperature of a refrigerant gas, which then becomes hot. The hot refrigerant flows into the condenser.
  2. Condensation: In the condenser the refrigerant releases heat to its surroundings, usually through metal fins and a fan. Resulting in the refrigerant becoming a high-pressure liquid.
  3. Expansion: The liquid then passes through an expansion valve/device which drops the pressure. The refrigerant’s temperature begins to decrease, and becomes a low-pressure, low-temperature liquid-vapour mixture.
  4. Evaporation: The refrigerant then passes through the evaporator, where it absorbs heat from its surroundings. As it absorbs the heat, it evaporates into a low-pressure gas, completing the cycle.

Key components

Compressor: Increases the pressure and temperature of the refrigerant gas. Facilitates the movement of heat from one location to another.

Condenser: Heat exchanger, where high-pressure, high-temperature refrigerant condenses into a high-pressure liquid.

Expansion valve or device: Controls the flow of the refrigerant and drops its pressure and temperature.

Evaporator: Heat exchanger, where low-pressure liquid refrigerant absorbs heat and evaporates into a low-pressure gas.

Refrigerant: The working fluid within the heat pump system. As it absorbs and releases heat it changes state between liquid and gas, whilst transferring thermal energy.

Expansion Tank: Used to accommodate the volume changes in refrigerant during the different operating conditions, whilst helping to maintain pressure levels.

Air Handler or Water-to-Air Heat Exchanger: They distribute conditioned air or transfer heat to indoor spaces. Air handlers transfer conditioned air and Water-to-Air Heat Exchangers transfer heat through a coil.

Section 4 – Sizing and Selecting a Heat Pump

Factors to consider

Heating and Cooling Load: The heating and cooling load should be determined with the space available or the size of the home to accurately size the heat pump. Take into account insulation, square footage, orientation, and climate.

Climate conditions: Heat pumps have different performance levels at different temperatures. Ensure the heat pump selected is capable of heating and cooling adequately in extreme weather conditions.

Energy Efficiency: High ratings indicate greater efficiency and cost savings, look for a Seasonal Energy Efficiency Ratio (SEER) for cooling and a Heating Seasonal Performance Factor (HSPF) for heating.

Installation Space: Consider the size and dimensions of both the indoor and outdoor areas to ensure proper placement and ventilation requirements.

System Configuration: The appropriate system configuration needs to be determined, including whether it should be ducted or ductless. The number of indoor units needs to be decided if in multiple zones.

Cost and Budget: Consider the upfront cost of the system, including the equipment and installation expenses. To make an informed decision balance the upfront cost with the potential long-term savings.

Warranty and Maintenance: Review the warranty provided and consider the maintenance requirements. Regular maintenance ensures optimal performance and extends the system’s lifespan.

Heat pump capacity and energy requirements

When sizing and selecting a heat pump, consider its capacity and energy requirements. The capacity refers to the heating and cooling output, measured in British Thermal Units (BTUs) or kilowatts (KW).

The energy requirements refer to its energy efficiency and consumption. Energy efficiency ratings such as SEER and HSPF indicate the heat pump’s ability to deliver heating and cooling for a given amount of energy. Higher ratings mean higher efficiency and lower energy consumption.

It is important to balance the capacity with the energy requirements. Oversized heat pumps can lead to inefficiency and increased energy consumption. Undersized heat pumps will struggle to heat and cool the area. Consulting a professional can help you to adequately choose the best size for your homes required needs.

Calculating heating and cooling loads

Calculating heating and cooling loads is important as it involves determining the amount of heating or cooling capacity required to maintain a comfortable indoor environment.

To calculate the heating load, factors such as the home’s square footage, insulation levels, windows, doors, and climate need to be considered. The heat loss from the building due to the indoor and outdoor temperatures need to be estimated. Heat loss through walls, windows, roofs, and infiltration need to be taken into account.

To calculate the cooling load, factors such as the home’s orientation, insulation levels, windows, ventilation, and climate need to be considered. The heat gain from the building due sunlight, appliances and occupants needs to be estimated. The calculation requires sensible heat (temperature control) and latent heat (humidity control) to be considered.

Software programs or load calculations provide methodologies for accurate calculations. They consider factors including construction materials, occupancy patterns, and anticipated weather conditions. Consult a professional or use reliable software when carrying out the calculations.

Section 5 – Installation Considerations

Location selection

It is important to select the right location for the heat pump to optimise efficiency and grant maintenance access. For outdoor units, these should be positioned in an area that has sufficient air flow away from obstructions, such as plants or walls. The location should also be in an area that minimises noise to reduce disruptions to yourself and your neighbours.

For indoor units, if it is ducted it should be installed in a central location to allow efficient air distribution. With a ductless system the unit needs to be placed where optimal airflow and coverage can take place.

Ductwork requirements

Existing Ductwork Evaluation: Assess the condition and design of the existing duct system before installing a heat pump. To prevent energy loss and ensure efficient airflow check it is the proper size, sealed, and insulated.

Ductwork Modifications: Modifications may be necessary, such as adding or resizing ducts, sealing leaks, and improving insulation.

Duct Design for new Installations: Proper design is essential; it involves calculating the appropriate duct size based on the heat pumps capacity and airflow requirements. Carefully plan the layout to ensure balanced airflow and even temperature distribution.

Duct Sealing: This is crucial to prevent air leakage, as without it, energy waste, air loss and reduced efficiency can occur. Appropriate material should be used to seal joints and connections, including mastic or specialised tape.

Duct Insulation: Insulation helps to prevent heat gain or loss during airflow, improving efficiency. Insulating unconditioned areas like lofts can lead to conditioned air reaching intended areas and prevents thermal loss.

Airflow Balancing: This ensures that heated or cooled air is evenly distributed. A balanced airflow can be achieved by adjusting dampers and registers.

Integration with existing heating or cooling systems

System Compatibility: The compatibility between the heat pump and existing heating and cooling system needs to be assessed. To make sure they can work together effectively. The fuel sources, ductwork, controls, and zoning need to be considered.

Control Integration: Make sure that when integrating a control system, it can co-ordinate with both the heat pump and existing system’s operations effectively.

Ductwork Evaluation: Evaluate the condition, design, and sizing of the existing ductwork before integrating a heat pump. Modifications and resizing of the ductwork may be necessary, to accommodate the heat pumps requirements.

Zoning Considerations: Determine how the heat pump can be integrated into the existing system’s zoning capabilities. Proper zoning ensures customised temperature control in different parts of the home.

Equipment Placement: Consider the available space, accessibility, and potential conflicts or obstructions when determining where to place a heat pump with an existing system.

Professional Evaluation: To assess the feasibility of the integration, seek the expertise of a professional. Who will be able to give guidance to help you make informed decisions. They can also help identify compatibility issues, as well as appropriate solutions.

Section 6 – Energy Efficiency and Performance


Coefficient of Performance (COP): This ratio represents the efficiency of a heat pump in heating and cooling mode. Divide the desired output (heating and cooling capacity) by the energy input (electricity or energy source). Higher COP equals higher efficiency, as more heat or cooling is produced per unit of electricity consumed. For heat pumps the COP values range from 2 to 5.

Energy Efficiency Ratio (EER): Measures the cooling efficiency of a heat pump or air conditioning system, by dividing the cooling capacity by the power input. A higher EER equals higher cooling efficiency, as more cooling capacity is produced per unit of energy consumed.

SEER (Seasonal Energy Efficiency Ratio): Measures the cooling efficiency of a heat pump or air conditioning system. It calculates the ratio of the cooling output (BTU – British Thermal Units) to electricity energy output (watt-hours) over the entire cooling season. A higher SEER rating equals higher efficiency, as a higher cooling output is produced per unit of energy. Typical ratings range from 13 to 26.

HSPF (Heating Seasonal Performance Factor): Measures the heating efficiency of a heat pump. It calculates the heating output (BTU – British Thermal Units) to electricity energy input (watt-hours) over the entire heating season. A higher HSPF rating equals higher efficiency, as a higher heating output is produced per unit of energy. Typical ratings range from 7 to 13.

Energy-saving features and technologies

Variable-Speed Motors (inverter-driven or variable-speed compressors): They adjust their speed based on the heating or cooling demand. They modulate their output to match the required load. Reducing energy waste, as speeds are lowered when less heating and cooling is needed.

Smart Controls and Thermostats: By utilising programmable settings, occupancy sensors and a Wi-Fi connection, temperature controls and schedules can be set. They can learn your preferences and adapt to changes in the weather. Smart controls can be used remotely for both operation and monitoring.

High-Efficiency Compressors: Advanced compressors are designed to increase efficiency. They optimise the compression process, reducing energy waste and increasing performance.

Enhanced Coil Design: Specially designed coils increase the surface area to increase heat transfer. Reducing energy usage and increasing the heating and cooling efficiency.

Advanced Refrigerant Technology: Newer heat pumps utilise environmentally friendly refrigerants with higher energy efficiency ratings, whilst lowering emissions.

Dual-Fuel Capability: This allows the heat pump to switch between electric and alternative fuel sources based on energy costs, whilst ensuring optimal energy usage.

Energy Recovery Ventilation (ERV): ERV systems recover and transfer heat or coolness from outgoing stale air to incoming fresh air, reducing the energy needed for conditioning incoming air.

Demand-Response Capability: This enables heat pumps to adjust their operation based on pricing or utility signals. This allows the heat pump to optimise energy usage during peak demand periods, to lower energy costs.

Section 7 – Benefits and Advantages

Energy Efficiency: Heat pumps are highly energy efficient as they transfer heat instead of generating it, creating significant energy savings. By utilising the air, ground, or water as heat sources, heat pumps can provide heating and cooling with minimal energy consumption.

Heating and Cooling in One System: Heat pumps can efficiently extract heat from outside air in colder months to warm indoor spaces and reverse the process in warmer months to cool the same space. Eliminating the need for separate systems, saving space and money.

Versatility in Heat Sources: Various heat sources can be utilised depending on the model, sources include air, ground, and water. Due to their versatility, heat pumps can be used in different environments and climates, ensuring efficiency throughout the year.

Environmentally Friendly: Heat pumps, when compared to traditional combustion-based systems, produce significantly lower greenhouse gas emissions, due to the use of renewable heat sources.

Consistent Comfort: Consistent and even heating and cooling can be provided through a heat pump, eliminating fluctuations in temperature and cold spots. Maintaining a comfortable indoor environment that can be adjusted depending on desired temperature.

Quiet Operation: Due to fewer mechanical components that operate at lower noise levels.

Reduced Operating Costs: Due to their high energy efficiency, over time significant savings can be made to utility bills, creating long-term financial benefits.

Long Lifespan and Durability: They are designed for long-lasting performance, the average lifespan 15-20+ years. Due to their durability and longevity, there is no need to frequently replace parts, which reduces waste, saves money, and lowers negative environmental impacts.

Section 8 – Maintenance and Troubleshooting

Regular maintenance tasks

Air Filter Cleaning/Replacement: Regularly check, clean, or replace air filters. Dirty filters can restrict airflow and reduce efficiency. Air filters should be replaced every 1-3 months depending on usage. Clean filters help to maintain good indoor air quality and ensure efficient operation.

Outdoor Unit Cleaning: The unit needs to be clear of debris, such as leaves, dirt, and vegetation. Remove obstructions that could hinder airflow and heat transfer.

Refrigerant Levels: Regularly check the refrigerant levels, low levels can indicate there is a leak or other issues.

Coil and Fin Cleaning: Clean the evaporator and condenser coils regularly to remove dirt and debris. Dirty coils reduce efficiency and performance. Inspect the fins and straighten if bent to maintain proper airflow.

Condensate Drain Cleaning: Make sure the drain line is clear and free of blockages. A blocked drain can cause water leakages or system damage.

Lubrication: Lubricate the motor and other moving parts, to reduce friction and help maintain operation.

Inspect Electrical Components: Inspect and tighten electrical connections, terminals, and wiring regularly to ensure safe and reliable operation. Check for signs of wear, corrosion, loose connections, or damage to wiring. Any issues should be dealt with as soon as possible.

Thermostat Calibration: Regularly check and calibrate the thermostat to ensure accurate temperature control and increase efficiency.

System Performance Check: Regularly monitor the system’s performance. Check for unusual noises, vibrations, changes in efficiency, and leaks. If issues arise contact a professional technician.

Annual Professional Maintenance: Schedule maintenance with a qualified HVAC technician. They can inspect, and clean the system, test the electrical components, and address any issues.

Section 9 – Compatibility with Other Systems

Combination with solar panels or other renewable energy sources

Renewable Energy Utilisation: By connecting a renewable energy source (solar panel, wind turbine, etc.) to a heat pump, the clean and sustainable energy can be utilised for heating and cooling purposes. Reducing the reliance on fossil fuels and lowering greenhouse gas emissions.

Energy Independence: Combining renewable energy sources and heat pumps promotes energy independence for homeowners. Reducing your dependence on the electrical grid, leading to lower energy costs, and a more resilient system.

Increased Energy Efficiency: Combining heat pumps with a renewable energy source enhances energy efficiency. The energy input reduces carbon emissions that are usually associated with traditional electricity generation.

Net Zero Energy Homes: This can occur when the energy produced by the renewable energy source matches or exceeds the energy consumed by the heat pump and other household needs.

Environmental Sustainability: Using a renewable energy source, significantly reduces or eliminates all carbon emissions linked to traditional heating and cooling methods. This helps to mitigate climate change, improve air quality, and conserve natural resources.

Government Incentive: Many governments offer incentives to promote the adoption of renewable energy and energy efficient technologies. Combining heat pumps with a renewable energy source can help homeowners qualify for these incentives, making installation more financially attractive.

Smart home connectivity and automation

Smart Thermostats: This enables homeowners to control their heat pump and temperature via smartphone apps or voice commands from their homes or anywhere else. They also offer scheduling controls, as well as the ability to learn algorithms that adapt to user preferences and optimise energy usage.

Energy Management: Energy management platforms can be integrated with smart home systems. By analysing energy consumption patterns and real-time data, owners can understand their energy usage. Helping to identify energy saving opportunities, set usage targets, optimise heat pump operation for maximum efficiency.

Integration with Home Automation: Heat pumps can be integrated with other smart home devices and systems for co-ordinated actions.

Demand Response Integration: During periods of high electricity demand, the heat pump can be remotely adjusted to reduce the load on the electrical grid. Homeowners can opt into these programmes and receive incentives to allow brief adjustments, contributing to grid stability and reducing the strain on energy infrastructure.

Energy Monitoring and Reporting: Monitoring and reporting on energy usage can help homeowners to make informed decisions and adopt energy efficient practices.

Integration with Voice Assistants: Systems can be voice controlled, allowing users to adjust settings and request information easily.

Section 10 – Cost Considerations

Long-term energy savings and payback period

Energy Efficiency: Heat pumps are highly efficient, providing 300-400% efficiency compared to electric resistant heating. For every unit of electricity consumed, 3-4 units of heat energy is generated.

Lower Operating Costs: Compared to conventional systems, heat pumps reduce both heating and cooling costs. Due to the use of a renewable energy source, there is a lower energy consumption and utility bills are reduced over time.

Potential for Renewable Incentives: Government incentives, grants, and programmes help to promote the adoption of heat pumps. These incentives can provide financial support and help to offset the initial installation costs.

Payback Period: Installation costs, energy prices, and energy consumption patterns can all affect the payback period. The payback period usually ranges from 5-15 years, although this depends on circumstance or location.

Financing options and available incentives

Government and Utility Rebates: Many governments and utility companies will offer rebates and incentives to encourage the adoption of energy efficient technologies, such as heat pumps. They can help to offset installation costs, making heat pumps more affordable to consumers. Rebates may include cash incentives, tax credits, or subsidised financing options.

Energy Efficiency Programs: These programs may provide financial incentives based on the savings in energy achieved by using a heat pump. They also promote heat pump adoption into homes, as well as reducing energy demands on the electrical grid.

Tax Credits: Homeowners may be eligible for tax credits when they install a heat pump. These tax credits can lower tax owed and provide additional financial relief.

Renewable Energy Incentives: Additional incentives are available for the use of heat pumps that are powered by a renewable energy source. These incentives promote renewable energy adoption and reduce reliance on fossil fuels. Previous incentives included the Domestic Renewable Heat Incentive (RHI).

Financing Options: Financing options may be offered by financial institutions to allow energy-efficient home upgrades, such as the installation of a heat pump. Options may include low-interest loans, flexible payment plans, or rebates.

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