A comprehensive guide to air source heat pumps.

Air source heat pumps, they might not be as familiar to you as your trusty everyday boiler, but these wonderfully innovative bits of tech are fast becoming a cleaner, more efficient way to heat your home. So, let’s take a closer look:

What is an air source heat pump?

An air source heat pump system is an energy-efficient home heating technology that extracts heat from the outdoor air and transfers it inside to provide you with heating and hot water for your home. They’re versatile, they’re eco-friendly, and they’re the future of sustainable home heating. Find out more about how air source heat pumps compare to gas boilers.

How do heat pumps work?

An air source heat pump (also known as an air-to-water heat pump), uses a special kind of fluid (called a refrigerant) to absorb heat from the outside air. This fluid is then circulated through a heat exchanger, so that its temperature is increased by the heat pump. It’s this intensified heat, which is then transferred to water, which can then heat your home through your radiators or provide hot water for your taps, showers, and baths.

You could think of it like a fridge in reverse. 1. Heat Pump’s special liquid absorbs heat from outside air (this works even if the temperatures are as low as -25°C). 2. The heat pump then compresses the liquid to increase its temperature before transferring this heat to your heating system. 3. Your heat pump can now heat your water to 45-55°C, which is more than enough for your hot water and radiators.

Learn more on how heat pumps work.

How efficient are air source heat pumps?

Air source heat pumps can give you up to four times more heat for each unit of energy used to power it. Although your actual savings will depend on the fuel you currently use to heat your home and the efficiency rating of your boiler.1

What’s the most efficient way to run an air source heat pump?

There are many ways you can ensure you get the most from your heat pump:

1. Use weather compensation. Enable the weather compensation feature if it's available, this automatically adjusts the flow temperature based on outdoor conditions. It allows your heat pump to run at lower temperatures when possible, improving efficiency.²

2. Maintain a steady temperature. Rather than frequently adjusting the temperature, aim to keep a consistent, comfortable setting. This approach is more energy-efficient than turning the system on and off.³

3. Lower the flow temperature. Run the heat pump at the lowest possible flow temperature that still maintains comfort. Lower flow temperatures increase efficiency and reduce running costs.

4. Keep the heat pump on for extended periods. Instead of turning the system off completely, use a "set-back" approach where you lower the temperature by a few degrees when you're away or sleeping. This is more efficient than letting the home cool down significantly and then reheating.²

5. Upgrade radiators if necessary. Ensure your radiators are sized correctly for lower flow temperatures. Larger radiators or underfloor heating work best with heat pumps.²

6. Maintain the system. Regularly clean the dust filters on indoor units and keep the outdoor unit free from debris. It’s good to have the system professionally serviced annually.³

7. Optimise airflow. Ensure good air circulation by keeping doors and windows closed and directing airflow into open spaces. Keep the outdoor unit clear of obstacles.³

8. Use appropriate modes. Utilise the auto mode for general operation, but switch to specific modes (like heat or cool) when necessary, based on conditions.³

9. Consider combining with solar panels and batteries. This can further reduce electricity costs, especially when paired with a time-of-use tariff.² Why not visit our solar page to shed a little light on solar? By implementing these strategies, you can maximise the efficiency of your air source heat pump, reduce energy consumption, and lower your heating costs while maintaining a comfortable home environment.

At what temperature are air source heat pumps most efficient?

Ideally, a heat pump should send hot water to your radiators at between 35°C and 45°C to be most cost effective. This is in comparison to fossil fuel boilers, which are designed to send water to your radiators at up to 75°C. Not to worry though, you can still heat your home effectively even at these lower temperatures.

What are the different types of air source heat pump?

There are many types of air source heat pumps available in the market, each designed to suit different property sizes and heating requirements.

1. Air-to-water heat pumps. These are the most common type in the UK. They absorb heat from the outside air and transfer it to a wet central heating system, providing both space heating and hot water. Air-to-water heat pumps are most effective with larger radiators or underfloor heating due to the lower temperature heat they produce compared to conventional boilers.

2. Air-to-air heat pumps. These systems take heat from the outside air and circulate warm air inside the home using fans. They can also operate in reverse during summer, providing cooling like an air conditioning unit. However, air-to-air heat pumps cannot produce hot water, so a separate system is needed for that purpose.

3. Variations and hybrid systems. These combine an air source heat pump with a traditional gas boiler. The heat pump handles most of the heating, with the boiler providing backup during very cold weather or for high hot water demand.

What is a ground source heat pump?

Ground source heat pumps are another energy-efficient alternative to conventional gas boilers. These systems harness geothermal energy from relatively shallow depths, typically extracting heat from groundwater using a network of boreholes, subterranean pipes, and pumps. In addition to providing warmth, ground source heat pumps can also cool homes by reversing the process, transferring indoor heat into the ground. There are two primary types of ground source heat pump systems:

1. Open loop systems. These directly extract groundwater, which carries thermal energy. The water is pumped to the surface, where its heat is harvested before being returned to the aquifer (the sediment or rock that holds groundwater).

2. Closed loop systems. These use a sealed circuit of pipes filled with a heat-transfer fluid (usually a water and antifreeze mixture). As this fluid circulates underground, it absorbs heat from the surrounding soil or rock. The warmed fluid then passes through a heat exchanger, where the thermal energy is transferred to the home's heating system.

Both types efficiently capture and utilise the Earth's stable underground temperatures to maintain comfortable conditions inside homes year-round, offering a more sustainable heating and cooling system compared to traditional methods.⁴ You can find out more about geothermal energy here.

The benefits of air source heat pumps.

Are heat pumps better for the environment?

Yes. Heat pumps are a more efficient use of electricity than boilers so they overall help to reduce CO2 emissions in the production of electricity. Compared to a gas boiler, an air source heat pump can reduce your annual carbon footprint by up to 44%.⁵ A heat pump’s lower-carbon credentials can amount to a saving of about 2,900 kg/year for a G-rated boiler. For an A-rated boiler, it’s a still-impressive 1,900kg/year.⁶

How much could I save with an air source heat pump?

Since heat pumps are more efficient than traditional gas or oil boilers, they use less energy to produce the same amount of heat. This can lead to cost and CO₂ savings. For example, replacing an older, inefficient gas boiler with a well-designed heat pump can save you around £340 a year on energy bills.⁷ Households with electric heating systems or those using LPG (liquid, petroleum, gas) or oil could see even greater savings. Exactly how much you save will depend on several factors though, including the type of heating system you are replacing, the efficiency of your heat pump, and the insulation of your home.

Learn more about the benefits of heat pumps vs boilers.

Heat pump installation.

How much does it cost to install an air source heat pump?

The cost of installing an air source heat pump depends on several factors, including the size of your property and how well it is insulated, however, as an example, a three bedroom detached house installation would typically cost between £10,000 and £20,000.⁸

How long does it take to install a heat pump?

The installation of a heat pump system usually takes around two to three days. This can vary depending on the amount of additional work that needs to be done for the new system, such as installing new radiators or a new hot water tank.

Once the system is up and running, it shouldn’t require much maintenance and should continue to provide heating and hot water for your home for up to 20 years. It is recommended though, that you service your heat pump annually through a qualified heat pump engineer to ensure it continues to work efficiently for as long as possible.

Is an air source heat pump right for you?

If you’re thinking about getting an air source heat pump, it’s important you consider how your home is set up so you can make the most of the heat your new pump generates. That way you can consume less energy, lower your energy bills, and reduce your carbon emissions. You should consider:

• Space: The unit itself is similar in size to a refrigerator and needs ample space outdoors for optimal airflow.

• Hot water: Standard models often require a hot water cylinder, but alternatives like hybrid systems or heat batteries are available for homes with limited space.⁹

• Extra infrastructure indoors: Because air source heat pumps circulate water at a lower temperature than a typical boiler, you may need larger radiators or underfloor heating to heat your home efficiently.

• Home Adjustments: Heat pumps might necessitate larger radiators or underfloor heating to compensate for their lower water temperature. If you're planning renovations, it might be the perfect time to make these adjustments.

• Noise: Most heat pumps operate at a noise level similar to a refrigerator, but some can be louder. If noise is a concern, check for quieter models certified by organisations like Quiet Mark.¹⁰

• Cost: While government grants can offset the initial investment, heat pumps are generally more expensive than traditional boilers to purchase. Plus, the potential for lower running costs isn't guaranteed, and depends on various factors like your home's insulation and energy usage.

Is my home ready for an air source heat pump?

For heat pumps to work efficiently and to their full capabilities, it’s important your home meets certain criteria:

• Energy Performance Certificate (EPC) rating. Does your home have a valid EPC rating? For heat pumps to be installed at a property a current EPC rating of D or higher is required. You can find out more on the government website.

• Do you have insulation? Homes need an adequate cavity wall, and/or loft insulation to feel the benefits of a heat pump. If you have an EPC rating, it'll tell you if loft or cavity insulation is recommended in your home.

Will a heat pump work with my current heating set up?

In some cases, yes. Air source heat pumps could be integrated into your existing heating system, working with your radiators to distribute warmth throughout your home. Some adjustments may be necessary however, to achieve optimal performance. And it's recommended you have a professional assess your current setup to determine compatibility and suggest any modifications that might be needed (for example, adjusting your flow temperature or adding insulation).

Can I get a heat pump in my flat?

Your home should meet a few criteria if you’re going to install an air source heat pump. Starting with good insulation, to make the most of the heat your new pump generates. That way you’ll consume less energy, which can lower your energy bills as well as reduce your carbon emissions. You can learn more on home insulation with our handy guide here.

In addition to the outdoor space needed, the indoor part of the unit also requires sufficient space to operate and provide a consistent temperature. You may also need a compatible hot water tank, and to consider installing underfloor heating.

Since an air source heat pump operates at a lower temperature than conventional radiators, the large surface area of underfloor heating is needed to distribute the heat more evenly. Alternatively, upgrading your existing radiators to the modern, low-temperature variety with thermostatic valves can also improve performance. Remember, to do this, permission would need to be sought from the freeholder of the building that the flat/apartment is in.

Can I get grants to pay for a heat pump?

There are usually grants available for heat pumps. It does, however, depend on which country or region you live in.

• If you live in England and Wales, you can get £7,500 towards an air source heat pump with the Boiler Upgrade Scheme.

• If you live in Scotland, you might be able to get an interest-free loan or a grant to make your home more energy efficient.

• If you live in Northern Ireland, there isn’t a specific grant currently available but you can still ‘get heat pump ready’ and apply for funding for insulation via NI Energy Advice.

I rent my property, can I ask my landlord to install a heat pump, are there grants for that?

Yes, you can ask your landlord to install a heat pump. There are grants available to help cover the costs. The Boiler Upgrade Scheme is also available to private landlords in England and Wales and aims to encourage the adoption of low-carbon heating systems. Landlords can receive up to £5,000 off the cost of an air source heat pump or £6,000 for a ground source heat pump. Additionally, landlords can apply for other grants for energy efficiency upgrades, such as insulation, which can further reduce costs.

Upgrade to a heat pump.

Want to know more about heat pumps or perhaps get a heat pump quote? We can arrange a visit from our trained air source heat pump surveyors, who will assess what needs to be installed at your property, and the most efficient positioning of your heat pump. After that, we’ll make a date for the installation itself, which will be carried out by professionals at no extra cost. Rest assured, they’ll also give you plenty of help and instruction with how it works, so you feel fully in control of your new heating system.

Air source heat pumps: A cost effective, energy-efficient tech for well-insulated homes.

In summary, while the initial investment in an air source heat pump can be high, government grants and the potential for significant energy savings make it a cost-effective and environmentally friendly option in the long run, especially for homes with good insulation and those replacing older, less efficient heating systems.

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