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Air Source Heat Pumps Explained

Ever wondered how air source heat pumps work? Are they a fit for every home? What's their role in UK's net zero mission? Keep reading for air source heat pumps explained.

What is an air source heat pump?

Air source heat pumps (ASHPs) offer an incredible new form of low-carbon heating. They harness warmth from the outside air and use it to provide heating and hot water for your home, even in temperatures as low as -15°C.

When installed in a well-insulated home, heat pumps offer the same level of comfort, cost-effectiveness, and convenience as gas boilers. The key difference is that heat pumps operate on electricity rather than gas, making them a far greener option.

This is excellent news for both your personal carbon footprint and for the UK's strides toward achieving Net Zero.

An air source heat pump installed at a residence
REM install air source heat pumps

How do air source heat pumps work?

Air source heat pumps operate on a similar principle to how refrigerators and freezers maintain their cool temperatures, but in reverse.

Here's how it works: The pump draws in outside air and uses it to warm a special refrigerant liquid. As the liquid heats up, it transforms into a gas.

This warmth is then compressed, boosting its temperature and generating a generous amount of heat for your home.

After the gas has released its heat, it cools down, returns to its liquid state, and starts the cycle anew.

What's remarkable is that this entire process relies solely on electricity, boasting an energy efficiency of over 350%. In comparison, a gas boiler operates at roughly 90% efficiency.

Although the science behind heat pumps may sound groundbreaking, it's not a new concept. Scientist Lord Kelvin first described it in 1852.

The pros and cons of air source heat pumps


1. Cost-Effective Heating: Provides more cost-efficient heating compared to a hot water boiler system.

2. Environmental Benefits: Significantly reduces your home’s CO2 emissions and contributes to better local air quality.

3. Government Incentives: Homeowners in England, Wales, and Scotland can benefit from government grants and schemes.

4. Affordable Options with British Gas: Offers flexible payment plans, including 0% interest over 2 years.

5. Integration with Solar Panels: Some models can be combined with solar panels for a more self-sufficient energy system.


1. Initial Cost: Heat pumps may have a higher upfront cost compared to gas boilers, although government support is available.

2. Property Suitability: Not all properties may have the appropriate space, access, or surroundings for heat pump installation. A free British Gas home survey can assess suitability and recommend any necessary home adjustments.

3. Insulation Requirements: To achieve optimal efficiency, your home should have effective insulation to retain heat.

4. Installation Challenges: Installing a heat pump might involve additional expenses and potential disruptions, such as upgrading central heating pipes and radiators.

Curious if a heat pump is the right fit for your home? Contact us today.

An external air source heat pump
We can install an air source heat pump for you

What are the different types of heat pump?

There are two primary types of heat pumps, each extracting heat from different sources. It's advisable to conduct some research before making a decision, but here are the key distinctions to consider:

Air Source Heat Pumps

  • Extract heat from the outdoor air using an external heat pump unit, which is then transferred into your home for heating.

  • Cheaper and simpler to install compared to ground source heat pumps.

  • Have higher running costs than ground source heat pumps.

  • The external heat pump unit is relatively compact, about the size of two washing machines.

  • Effective in temperatures as low as -15°C.

  • Typically do not require planning permission.

  • Have a lifespan of approximately 20 years.

Ground Source Heat Pumps

  • Extract heat from the ground using water circulating in underground pipes, providing heating for your home.

  • More costly and complex to install compared to air source heat pumps.

  • Have lower running costs than air source heat pumps.

  • Require excavation of a larger outdoor area (e.g., garden) for laying pipework.

  • More efficient in lower temperatures.

  • Have a lifespan of around 20 years.

There's also another type known as hybrid heat pumps. These can be either air source or ground source heat pumps, with an additional backup gas boiler that activates when extra heat is needed.

Regardless of the type you choose, you'll be heating your home in a more environmentally sustainable way compared to a traditional gas boiler. In fact, if your electricity comes from a zero-carbon source, you'll be heating your home without generating any CO2 emissions at all.

What government grants are available?

Replacing the nation’s gas boilers with greener, cleaner alternatives is a big part of the UK’s plans to reach Net Zero by 2050.

That’s why the UK authorities are offering financial incentives for people who make the switch to sustainable heating now.

England and Wales

The Boiler Upgrade Scheme was introduced in April 2022 (replacing previous schemes called the Renewable Heating Incentive and the Clean Heat Grant).

The scheme gives homeowners in England and Wales £7,500 to help with the initial cost of upgrading from a fossil fuel boiler to a low-carbon alternative, like an air source heat pump.


Homeowners in Scotland can apply for a £7,500 grant from Home Energy Scotland – with an extra £1,500 available for people living in rural areas.

Is an air source heat pump right for you?

Before committing to the installation of an ASHP, consider these essential points:

1. Assess Your Current Heating System: Is your existing system showing signs of aging, becoming unreliable, or requiring frequent repairs? If so, it might be an opportune moment to replace it, potentially with a heat pump.

2. Evaluate Exterior Space: Do you have sufficient outdoor space adjacent to your home that can accommodate a heat pump unit?

3. Check Insulation Levels: Is your home adequately insulated to maximize the benefits of a heat pump? If not, would you be open to investing in improved insulation?

If you've answered 'yes' to these questions, an air source heat pump could be a fantastic, environmentally-friendly heating option for your home.

Would you like to connect with one of our experts to discuss the possibility of installing a heat pump? Contact us today.

Air Source Heat Pumps Explained

Air source heat pumps are an energy-efficient heating solution, particularly in moderate climates like the UK, where outdoor air temperatures seldom reach extreme lows. They can extract heat from the air even when temperatures are below freezing, though their efficiency decreases as temperatures drop.

ASHPs are an attractive option for UK homeowners looking to install a new heating system as they offer reduced energy consumption, lower carbon emissions, and potential cost savings compared to traditional heating systems like gas boilers or electric heaters.

Hopefully what you need to know about air source heat pumps has been explained in enough detail for you to make a decision or an enquiry.


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