Heat pumps can be a wonderful alternative to a boiler, particularly as they allow you to create heat from the environment around you and could help you to reduce your carbon emissions.

The efficiency of a heat pump is calculated as a CoP unit, which stands for Coefficient of Performance. CoP calculates how efficient a heat pump is by measuring the amount of input compared to the amount of output. For example, if a heat pump uses one kW of electricity and four kW of heat is produced, the CoP is four. The higher the CoP, the more efficient the heat pump is.

How efficient is a ground source heat pump?

Ground source heat pumps use the ground as their main source of energy, and they do this via geothermal probes/collectors that are buried in your garden. They take heat energy from the ground and pass it through a heat exchanger into the heat pump. In doing this, they’re harnessing natural, renewable resources instead of burning fuel, such as gas. But how energy efficient actually is a ground source heat pump?

The ground temperature stays fairly consistent all year round, remaining at around 11 to 12 °C in the UK. This ground temperature will usually allow your heat pump to run at four CoP or higher.

According to the Centre for Sustainable Energy, you could reduce your CO2 emissions by around three tonnes a year by using a ground source heat pump in a four bedroom house. This is the equivalent of a flight from London to Hong Kong and back again. The average heat pump lasts around 25 years, which could mean a total saving of 70 tonnes.

As the government is trying to encourage people to use more renewable energy sources, you could receive a small income from the Renewable Heat Incentive for making use of a pump to heat your home.

How efficient is an air source heat pump?

An air source heat pump isn’t as efficient as a ground source heat pump, however, even with an outside temperature of -3°C to 10°C, many air source heat pumps will reach an efficiency level of around three CoP. This could increase with a higher outdoor temperature.

They may be better suited to warmer climates, as both ground and air source heat pumps can cool a room as well as heat it up. This may be especially useful for an environment like the UK, where temperatures are quite mild but can reach the mid-20s or higher during a heatwave.

Just like a boiler, you can use smart technology to control the pump using your smartphone, helping you to ensure your system works as efficiently as possible.

Do heat pumps remove humidity?

Some heat pumps can also act as dehumidifiers to help remove some of the moisture from your home.

The higher the temperature of a room, the more moisture the air can contain. This is why some hot countries, particularly in Asia, have a much higher humidity. This humidity can cause problems if you’re trying to cool your home down, so it needs to be reduced first.

A humidity of around 30 to 40 per cent is a good amount for us to stay cool and comfortable. Certain types of heat pump will be able to help maintain this level and keep rooms at a steady temperature.

The dehumidifier in a heat pump has two modes: the cooling mode and the drying mode. When the heat pump is in cooling mode, it is able to absorb heat and moisture in the air, which is then expelled outdoors. A fan within the outdoor unit allows the heat to be released. When the heat pump is in dry mode, it alternates between heating and cooling, therefore maintaining a room’s temperature whilst also removing the excess moisture.

In both modes, as the pump takes the moisture out of the air, you’ll begin to see a noticeable drop in temperature.

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Do heat pumps need servicing?

Just like your boiler, a heat pump needs servicing regularly, particularly if you want it to reach a life span of 20-30 years.

Most ground source heat pumps will require an annual check to ensure they’re still operating efficiently. A heat pump that isn’t running as well as it should be could lose up to 25 per cent efficiency, so it’s important to make sure it’s serviced. You may save money this way.

You should check your manufacturer’s information booklet, as they will specify how often your pump should be serviced.

The service for your ground source heat pump should include a check of the following:

  • Electronics and control equipment
  • Compressor
  • Antifreeze in the ground
  • Water pump
  • Pipes and connectors


These checks should only be done by a suitably qualified engineer. The heat pumps can contain F-Gas refrigerants, so an ‘F’ Gas certified engineer will be required to check these parts.

An air source heat pump requires a few more checks. These include:

  • Cleaning of filters
  • Removing debris or dust that could block the air flow
  • Cleaning of fan blades
  • Checking of refrigerant levels
  • Checking for leaks

Your heat pump shouldn’t need any parts replacing unless they’re damaged. Most pumps will come with a five to 10 year guarantee, however it should last much longer than this if it’s serviced annually.

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