Air source heat pumps explained - which ones? (2023)

An air source pump is an alternative way to heat your home. It allows you to generate your own renewable heat and potentially save money on your energy bills in the long run.

They provide heat at lower temperatures than gas and oil boilers. So you have to run them much longer to heat your home to a comfortable temperature.

A well-insulated house is essential - otherwise the heat generated by the pump will escape more easily and you may find that the temperature does not reach normal levels.

With heat pumps, you also save on heating costs when you replace expensive systems such as electric storage heaters, oil, LPG (liquefied petroleum gas) or coal. You won't see as much of a cost saving if you replace a gas boiler - although you will still significantly reduce your CO2 emissions.

Other options for generating your own energy are:

  • geothermal heat pumps
  • Solar-PV-Module(for electricity)
  • Solar water heating
  • wood stoves.

Read on to learn more about the pros and cons of air source heat pumps so you can decide if purchasing one is the right decision for you.

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How does an air source heat pump work?

An air source heat pump extracts heat from the air and raises it to a higher temperature using a compressor. It then transfers the heat to your home's heating system.

They work a bit like inverted refrigerators.

Air source heat pumps explained - which ones? (1)
  1. The air source heat pump absorbs heat from the outside air into a liquid refrigerant at low temperature.
  2. Using electricity, the pump compresses the liquid to raise its temperature. It then condenses back into a liquid to give off its stored heat.
  3. Heat is directed to your radiators or underfloor heating. The rest can be stored in your hot water tank.
  4. You can use your stored hot water for showering, bathing and tapping.

The pump takes electricity to run, but it should use less electrical energy than the heat it generates. This makes them an energy efficient way to warm your home.

Air source heat pumps also work when the temperature is below zero.

Geothermal heat pumps also use natural heat and increase the temperature to warm your home. ExperienceHow geothermal heat pumps work.

What is an air source heat pump?

An air source heat pump is a low carbon way to heat your home. They absorb latent heat from the outside air and use it to increase the temperature in your home.

Air source heat pumps look similar to air conditioners. Their size depends on how much heat they need to generate for your home - the more heat, the larger the heat pump.

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There are two main types of air source heat pumps: air to water and air to air heat pumps. They work in different ways and are compatible with different types of heating systems.

Air to water heat pumps

Air/water heat pumps extract heat from the outside air and feed it into your wet central heating system.

They are best suited for larger radiators or radiatorsWater underfloor heatingbecause the heat they produce is cooler than that of a traditional gas or oil boiler. To be most effective, they need a large surface area to dissipate the heat.

It is easier to install larger radiators or underfloor heating for a heat pump when expanding or building a new home. It can also cost less than retrofitting underfloor heating later.

Air source heat pumps explained - which ones? (2)

Air to Air Heat Pumps

Air-to-air heat pumps extract heat from the outside air and direct it into your home via fans. You need a warm air circulation system to distribute heat throughout your home.

These systems cannot produce hot water, so you will need a separate immersion heater or other water heating system.

In summer, an air-to-air heat pump can work in reverse. In other words, you can use it like an air conditioner to bring cool air to your home.

If you are looking for an air conditioner, check out oursair conditioning reviews.

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Installation of an air source heat pump

Air source heat pumps explained - which ones? (3)

Air source heat pumps are typically installed outdoors at the side or rear of a property. They need plenty of space around them for air to circulate.

Inside you usually have a unit with pumps and hot water.

They are less disruptive to install than ground source heat pumps as they do not require digging in your garden.

You normally do not need planning permission for an air to water heat pump, but if you live in a listed building or in a conservation area you will usually need permission from your local authority. You must also verify that your installation complies with building codes in your area.

Also speak to your home insurance company to check if your policy will cover the changes to your heating system.

When purchasing an air source heat pump, it is important to ensure your home is well insulated so it can retain heat. In addition to heat pumps, underfloor heating or larger radiators are often installed to better distribute the heat.

Your installer should explain how to use the controls for your heat pump so that you can use it most effectively. You probably need to heat your home longer, but at a lower temperature.

When your system is complete, you should receive a commissioning certificate from the installer. They should also receive a Microgeneration Certification Scheme (MCS) installation certificate once the system has been registered (the installer must do this within 10 days). You need these to qualify for most grant programs.

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Advantages and disadvantages of an air source heat pump

Air source heat pumps explained - which ones? (4)

Air source heat pumps are low maintenance and can provide heating and hot water, but they are not error-free systems. Here are some of the main pros and cons:


  • Energy Efficient and Low Carbon - Air source heat pumps produce less CO2 than many traditional heating systems
  • Less annoying thanInstallation of a geothermal heat pump, especially if you are retrofitting
  • You can save money on heating compared to some older systems.


  • You need enough space in your garden for the external condenser unit
  • Condensing units can be noisy and blow colder air into the immediate area around them
  • Electricity is needed to run the pump so it's not carbon free (unless the electricity comes from a renewable source like solar panels or a wind turbine).

Are air source heat pumps efficient?

An air source heat pump system can help reduce your carbon footprint because it uses a renewable, natural heat source - air. How much CO2 you save depends on which fuel you replace. For example, if you substitute coal or an oil boiler instead of natural gas, the number will be higher.

A heat pump requires an energy source, usually electricity, to power the heat pump, so there are still some CO2 emissions.

To get the most out of your heat pump, you need to know how to use it most effectively. You often have to turn on your heating longer than with a conventional system. Your installer should show you how to control your heat pump system.

You should also have your heat pump serviced every two to three years. Periodically inspect all grills to ensure they are free of leaves and debris, and follow any other maintenance checks recommended by your installer.

Energy labels for heat pumps

Heat pumps must have an energy label. It indicates how energy efficient the pump is on a scale from dark green (most efficient) to red (least efficient).

Since September 26, 2015, all new heat pumps must be sold with an EU product label. The installer should also create a packaging label that shows efficiency based on several different components in the heating system.

All MCS certified heat pumps must be sold with a product label and the installer must create a packaging label.

(Video) Introduction to Air Source Heat Pumps

Continue reading:Tips for saving electricity and money


What is the most reliable air source heat pump? ›

What are the best air source heat pump brands?
  • Best overall: Samsung EHS Monobloc.
  • Most efficient: Hitachi Yutaki.
  • Most powerful: Vaillant flexoTHERM 400V + aroCOLLECT.
  • Best for cold climates: Daikin Altherma.
  • Best for small homes: Nibe F2040.
  • Best for combining other sources: Calorex.
  • Best for scalability: Danfoss.
Jan 4, 2023

Do air source heat pumps provide enough heat? ›

An important disadvantage to be aware of is that air source heat pumps have a lower heat supply than other alternatives. This means to get the most out of your ASHP, you need to have a well-insulated home and, ideally, underfloor heating, too.

What temperature should I set my air source heat pump? ›

The heat pump should heat your hot water tank to around 35-40°C. However this is not hot enough to kill any bacteria within the tank. Therefore the tank should be timed to heat up to 60°C once a week - you will notice a corresponding spike in your electricity usage.

What are the pros and cons of an air source heat pump? ›

Overview: Pros and cons of air source heat pumps
Environmentally friendlyExpensive running costs
Low maintenanceExpensive upfront cost
Efficient modelsNot suitable for all properties
Eligible for various grantsRelies on electricity, which isn't always green
5 more rows
Oct 24, 2022

What is the best cold weather air source heat pump? ›

Based on our research, the best cold climate heat pump is Mitsubishi's Hyper-Heating, or H2i. Listed as Mitsubishi's M-Series or P-Series for home installation, these heat pumps maintain their full heating capacity down to 5F, and can produce useful heat down to -13F.

At what temperature do air source heat pumps stop working? ›

The Minimum Temperature Requirements for Heat Pumps

For the brands and models that are towards the higher end, you can expect the efficiency to stop at around -18 to -22 degrees Celsius. You may even be lucky enough to find models that will remain efficient up to -25 degrees Celsius.

Is it worth getting an air source heat pump? ›

Yes. An air source heat pump will typically save you £6,700 over its lifetime, compared to a gas boiler – which means you can actually cut your costs by going green.

Why is my electric bill so high with air source heat pump? ›

Improper maintenance of your heat pump could lead to a 25 per cent increase in your energy bills. Blocked and dirty filters reduce the amount of airflow that can pass through the system and may harm performance. It's also worth checking the fan regularly to ensure there isn't any debris, such as leaves, stuck in it.

Which heat pumps last the longest? ›

A dual-source pump usually lasts the longest out of all three kinds. Heat pumps are more efficient than air conditioners because they both heat and cool your home; there is no need to install a heating and a cooling system.

How long do air source heat pumps last? ›

Air source heat pumps can be installed in a matter of just a couple of days and can go on to last up to 20 years. They require minimum maintenance, needing cleaning every couple of months and a yearly service.

What size heat pump do I need for 2000 sq ft home? ›

If you Google “heat pump calculator,” you'll probably find a rule of thumb like this: “You need 30 BTUs of heat for every square foot of living space you want to heat or cool.” If you have a 2,000-square-foot home, this rule of thumb suggests you need a 60,000 BTU heat pump.

Is the major problem of air source heat pump system? ›

Answer: Common air source heating problems include loss of heat production, lack of performance in freezing temperatures, noise, ineffectual location, and poor installation. These problems can be avoided by using a reputable installer.


1. What Are the Running Costs Of AIR SOURCE HEAT PUMPS? | GreenMatch
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4. Pros and Cons of Air Source Heat Pumps (2022) | GreenMatch
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