What is a heat pump and how do they work?

What is a heat pump?

A heat pump is a device that transfers heat from one place to another, and some heat pumps may even provide both heating and cooling for your home. It can efficiently regulate the temperature inside your home, making it a versatile and energy-efficient solution for managing your home's climate.

There are several different types of heat pumps, but the most common types used in the UK are air source, ground source, and water source heat pumps.

How does a heat pump work?

A heat pump works in a similar way to how an air conditioning system works, but instead of taking warm air from inside and venting it out, they take heat energy from the outside to heat your home.

The process of how a heat pump works can be broken down into five clear stages:

1. Heat extraction: Heat is captured from an external source (such as the air, ground, or water).
2. Heat transfer: The heat is then transferred to a refrigerant (a fluid that absorbs and carries heat). The refrigerant circulates through the system, moving the captured heat from the external source to a condenser.
3. Heat compression: Inside the heat pump, the refrigerant is compressed before it is passed through the condenser, which increases its temperature and pressure. This process concentrates the heat, making it hotter.
4. Heat distribution: The hot, pressurised refrigerant passes through the condenser which is basically a coil or heat exchanger inside the unit. At this point, the refrigerant releases its heat into the indoor air or water which heats your home.
5. Recycling: The refrigerant cycles back to the outdoor unit to start the process over again, continuously providing heating or cooling as needed. Where the ability to cool the house is possible, this process is reversed: The heat pump extracts heat from the indoor air and releases it outside, which cools your home.

What is a refrigerant?

A refrigerant is a fluid that absorbs and releases heat as it changes from liquid to gas, this enables heat transfer in systems like heat pumps and air conditioners.

What different types of heat pumps are there?

Although there are a few different types of heat pumps, the most common types of heat pumps in the UK are air source heat pumps, ground source heat pumps, and water source heat pumps.

Air source heat pumps

An air source heat pump is a type of heat pump that works by transferring heat from the air to a building. Air source heat pumps can be used to heat your home, but they can also be used to heat water that’s stored in a hot water cylinder, which provides hot water in your home.

Air source heat pumps are compatible with various property types and are the most common type of domestic heat pump used in the UK. Their relatively easy installation—requiring only an outdoor unit—and their ability to function year-round make them a popular, versatile choice for homeowners seeking low-carbon heating systems.

Ground source heat pumps

A ground source heat pump is a type of heat pump that extracts heat from the ground and transfers it to provide heating and hot water for a building.

Ground source heat pumps use a network of buried pipes filled with a heat transfer fluid that absorbs heat from the ground and transfers it to the heat pump. As the ground generally maintains a relatively constant temperature throughout the year, ground source heat pumps operate efficiently in all seasons.

Compared to air source heat pumps, ground source heat pumps require a larger area for installation. This is essentially because the pipes need to be laid horizontally in trenches or vertically in boreholes.

Water source heat pumps

A water source heat pump is a type of heat pump that extracts heat from a nearby water source, such as a lake, river, or well, to provide heating and hot water for a building. They can be used for both heating and cooling, depending on the configuration.

This system works by using submerged pipes to absorb heat from the water, which is then transferred to the heat pump. Water source heat pumps are particularly efficient because water bodies tend to have more stable temperatures compared to air, allowing for consistent heat extraction throughout the year.

Installation requires access to a suitable water source, and the pipes must be submerged or installed in a closed-loop system.

Should I get a heat pump?

Going from the traditional boiler heating system to a heat pump system is a big decision, so it’s important to be aware of the advantages and disadvantages that come with owning a heat pump before making the change.

What are the advantages of having a heat pump?

Some key advantages of a heat pump include:

• Energy efficient: Heat pumps can produce more heat or cooling energy than the electricity they consume, making them more energy-efficient in most cases.
• Long lifespan: They are designed to last many years, often outlasting traditional heating and cooling systems like boiler heating systems. Dual functionality: With heat pumps you can benefit from both heating and cooling, eliminating the need for separate systems.
• Low maintenance: Generally, heat pumps require minimal upkeep compared to other heating and cooling systems, with fewer components that need regular servicing.
• Safe operation: As heat pumps don’t involve combustion, this means there are no byproducts from the combustion process such as hot air and gases, which are normally removed by your boiler flue.

What are the disadvantages of a heat pump?

Some key disadvantages of a heat pump include:

• Initial cost: Heat pumps often have a higher upfront cost compared to traditional heating and cooling systems, though they may save money in the long run through lower energy bills.
• Installation challenges: The installation process can be complex and may require modifications to existing systems or infrastructure.
• Less efficient in cold temperatures: In extremely cold climates, heat pumps may struggle to maintain efficiency and may require an additional heating source to keep indoor spaces at a comfortable temperature.
• Requires space: Heat pumps need adequate space for both indoor and outdoor units.
• Electric Supply: Before any work is started check with your energy supplier to ensure that the electrical supply to your property is sufficient to operate the heat pump.

Common heat pump questions

If you still have some burning questions about heat pumps, we’ve compiled a list of some of the most common questions and answers below.

How does a heat pump work in winter?

Heat pumps work the same way in winter as they do throughout the other months of the year, by extracting and transferring heat from the outside to the inside of your home.

How much electricity does a heat pump use?

According to an EnergySage analysis of a Department of Energy database, a typical heat pump in a typical home will use around 5,475 kiloWatt hours (kWh) per year. In most cases, this is likely to be the highest energy user in the home.

However, it’s important to bear in mind that there are lots of different factors that will affect what this figure looks like. This means it’s more useful to look at this as a range of between 400 kWh and 22,500 kWh, according to analysis by EnergySage.

Can a heat pump cool a house?

It depends on the heat pump you use. Some heat pumps have the ability to heat but also cool your home by moving heat from inside the house to outside through the reversing valve. These heat pumps are sometimes referred to as split units.

Thinking about getting an air source heat pump?

Are you thinking about upgrading your current heating system with an air source heat pump? Make an informed decision by exploring our guide to air source heat pumps. Learn everything you need to know and see if it's the right fit for you!