Air Source Heat Pumps – Pros and Cons

Last updated: June 8, 2021

If you are looking to reduce your energy bills, then there are ‘new heating technology’ alternatives to gas or oil boilers you could consider. And one of the most popular alternatives to traditional heating systems are air source heat pumps.

A renewal heating technology, air source heat pumps are considered a greener heating method as they do not produce carbon emissions when in operation and can also offer cheaper energy bills and a more efficiently heated home. But you do need to ensure your home is well-insulated to get the very best out of this alternative heating method. And you will still need an electrical supply.

Switching your heating source to new technology can be a big change, so we take look at the pros and cons to help you decide if the air source heat pump route is the one for you.

What Is an Air Source Heat Pump?

Also known as an ASHP, an air source heat pump extracts heat from the air outside of your home to create enough heat to supply your central heating and hot water system. They typically look like an air conditioning unit which is fitted outside your home and come in two types: air to water or air to heat.

You could think of an ASHP as a refrigerator in reverse. It takes heat from the outside air and compresses it, so it reaches a higher temperature, using a heat pump. Air to water heat pumps have evaporators to convert the air to a liquid, and then raises the temperature, so it can be fed into both your heating as well as hot water systems. Air to heat pumps feed the heat into your home via fans and cannot produce hot water.  Some air source heat pumps can also operate as a cooling system during the warmer months.

You do need sufficient space outside your home for an ASHP to be installed. The pump also needs an electricity supply to run, which means unless your electricity is supplied by solar or wind, your system will not be totally renewable.

An air source heat pump can be expensive to install – potentially as high as £10,000+ – but over time, if it is running efficiently, it should pay for itself, as they tend to last longer than a conventional boiler and you will see lower energy bills over the long-run. And ASHPs qualify for the government’s Renewable Heat Incentive, which could mean you get a grant towards the cost of installing renewable technology.

You can read more about air source, as well as ground and water source heat pumps in our blog, How Does a Heat Pump Work?

Pros and Cons

Before we look in depth at the benefits of an air source heat pump, as well as disadvantages, here’s our summary of the main pros and cons when it comes to fitting and using an ASHP in your home:

CONSPROS
Not suited to all properties – you need outdoor space as well as compatible radiators or underfloor heating to get the best out of an ASHP.Qualify for RHI – as a renewable technology, air source heat pumps can mean you could get a grant from the government.
You may need new radiators – the lower temperature of the water ASHPs supply, may mean you need larger radiators to create more heat surface area.Work in lower temperatures – ASHPs are good for more temperate climates as they can extract heat from air temperatures as low as -20°C.
Lose efficiency in low temperatures – while air source heat pumps can work in lower temperatures, they lose efficiency below 0°C and will need more electricity.Easy to install – when it comes to renewable technology, air source heat pumps are one of the easiest to install.
Can be loud – ASHP units are known to be noisy when running, although newer models are getting quieter.Energy efficient – an ASHP could see a reduction in your energy bills.
They take up space – you will need enough space in your garden to be able to accommodate the external condenser unit.Low carbon footprint – ASHPs will generate less CO2 than conventional boilers and heating systems.

Advantages of Air Source Heat Pumps

There is a lot to like about air source heat pump technology and in many cases, it makes a workable renewable alternative to the traditional ways of heating your home. With efficiency and carbon emissions in mind, we take a look at the reasons why ASHP can be a good choice for domestic heating:

  • Versatility

While there is the initial inconvenience of having a new pump installed, ASHPs are a versatile way to heat your home. Depending on the model you choose, they can be used for both heating and cooling, depending on the time of year and provide both space and water heating. Another plus point for the air source heat pump is that they work very well with underfloor heating, which requires a lower temperature than radiators to generate the required warmth.

  • Reduced carbon footprint

Switching from a heating system that uses fossil fuels to an air source heat pump means you can significantly reduce your home’s carbon emissions. And while ASHPs do need an electricity supply to run, if you opt for wind or solar power for your energy then you can keep your carbon footprint to a minimum.

  • Potential energy bill savings

A switch to ASHP for your home heating needs can also see a reduction in your energy bills, compared to a heating system run on gas or electricity alone. As long as they are installed correctly, and the energy levels generated are appropriate for your home, an air source heat pump is also cheaper than oil or LPG.

  • Eligible for RHI

Air to water heat pumps are eligible for the government’s current green energy grant scheme, the Renewable Heat Incentive – or RHI. With the scheme deadline extended to March 2022, a successful application could see you receiving a payment for heat generated over a period of seven years.

  • Can Work in Lower Temperatures

Air source heat pumps can work well in lower outdoor temperatures, so are a good choice for colder and more temperate countries. They can actually work in ambient air temperatures as low as -20°C. They are also efficient to run in both the winter and summer.

  • Easy Installation Process

Compared to ground source pumps, an ASHP is easy to install as there is no digging involved, all you need is sufficient space to have the external unit installed. On average it takes an engineer around two days to fully fit an ASHP and they are good to install as a retro fit as well as straight into a new build.

  • Low Maintenance and long lifespan

To keep your air source heat pump in optimum operational fitness, a full service should be carried out by a fully qualified engineer once a year so it can be checked and fully cleaned. But generally, ASHPs are low maintenance, compared to other types of heating systems. Not only that, but on average, they have a longer lifespan, compared to a conventional gas or electric boiler, and can last for around 20 years.

  • No Fuel Storage Needed

Unlike other outdoor and even indoor boilers and heating systems, such as oil or wood pellets, there is no need for fuel storage, so not only can you avoid a space-stealing outdoor storage unit, but you save money on fuel deliveries.

  • Can be Powered by Wind or Solar Energy

While your ASHP does need an electricity supply to drive the internal heat pump, you can boost its renewable credentials even further by opting for an alternative source of electricity. Most air source heat pumps can be used in conjunction with wind or solar power to keep your carbon emissions to a minimum.

Disadvantages of Air Source Heat Pumps

So, now we have been through all the plus points of installing an air source heat pump into your home, it’s important to also be aware of the potential shortfalls so you can be sure an ASHP is the right heating system fit your particular property.

  • Requires outside space

You need to have sufficient outdoor space to house the external unit as well as surrounding area so that it has an adequate and unimpeded air supply. It will also need to be linked to a large hot water cylinder within your home.

  • It is visible

Unlike a gas or electric boiler, you can stash in the loft or away inside a cupboard, an ASHP is a large, air-conditioner like unit that may not be as aesthetically pleasing as you would like.

  • They give a lower heat

Unlike traditional heating systems, such as gas, which can get your water temperature up to 75-80°C, ASHPs have a lower operating temperature, producing water around 45°C. This means an air source heat pump is not suitable for all properties.

  • Your home needs to be well-insulated

To get the very best out of an air source heat pump, your home needs to be well insulated, and draughts kept to a minimum. If your home ‘leaks’ heat through windows, doors and the roof, then the ASHP is going to use more energy to keep your house sufficiently warm and you are not going to get the energy saving benefits.

  • You still need electricity

If minimising your carbon footprint is a priority, you need to be aware that ASHPs still need electricity to run. And if you are using it all year round, this means you will not necessarily see the energy savings you were hoping for. To be classed as a full renewable energy source, your ASHP will need to be run in conjunction with wind or solar power, instead of conventional electricity.

  • They tend to be on the noisy side

If you like absolute peace at home, then you may want to reconsider getting an ASHP. While the newest models are getting quieter, most air source pumps will make some noise while they are running, similar to an air conditioning unit. But it should not be excessive, more of a hum, than a full-on noise. If you are concerned, ask the engineer to install the unit away from your living areas and bedrooms if they can.

  • They lose efficiency below 0°C

While they work in low temperatures, that doesn’t mean they are perfect. In fact, air source heat pumps will lose efficiency once the temperature drops below 0°C. And the colder the air gets, the harder the pump has to work, and so you could well see your energy bills go up.

  • Can cost more to run than A rated boilers

Before making the switch to an ASHP, double check your existing boiler to see if it can give the air source heat pump concept a run for its money.  If you have an A rated gas boiler, that is relatively new and regularly serviced, you may find there is little if any difference in your heating bills, as electricity is more expensive per unit than gas.

  • Radiators may need to be changed

Another consideration when it comes to installing an air source heat pump system is whether your existing radiators are sufficient to make the most of the reduced water temperature the ASHP will produce. If not, you may find you have additional expense in upgrading your radiators to larger ones or replacing them with convection heaters.

ASHPs tend to work more effectively and efficiently with underfloor heating systems and warm air radiators rather than hot water heaters.

  • They are not suited to all types of properties

Taking into consideration all the other listed disadvantages of an air source heat pump, it’s clear that ASHPS are best suited to certain homes and heating systems. They are also not well-suited to certain types of properties if you need to retro fit an ASHP. Flats, terraces and homes with little or no outdoor space or no internal room for the hot water cylinder you will also need are not the right properties for air source heat pump technology.

The Final Word on ASHP

So, there you have it, the lowdown on air source heat pumps and the pros as well as cons of installing this renewable form of heating into your home. And the simple take-away is that this green form of energy is not suitable for every home.

But if you have the outdoor space and are planning a new build or have the right central heating system already in place, then an air source heat pump could save you money and keep you warm while helping to reduce your home’s carbon footprint. And that certainly makes this renewable energy source worth considering.