Heat pumps are becoming increasingly popular, but many homeowners face the same question: air source or ground source? Which is better, cheaper, or more economical? For Sussex homes, the answer ultimately lies in:
Air source heat pumps generally have a lower upfront cost and take up less space, however they can be less efficient and a little noisy. Ground source heat pumps have lower running costs, are more efficient, but will cost more upfront.
In this blog, we explore both so you can choose the optimal heat pump installation in Sussex from Sussex Aircon and Heat Pumps, the trusted and experienced name in air conditioning and heat pumps for the county.
An air source heat pump, or ASHP, pulls heat from the air outside and uses it to warm your home. A fan within the system draws this air in, with the heat absorbed by a refrigerant. The refrigerant then turns into a gas when it gets warm. To make it hotter and more useful for your heating system, this gas is compressed. Sitting outside your home, it may look similar to an air conditioning unit.
A ground source heat pump, or GSHP, is also outside your home, but rather than relying on air as its heat source, it takes its energy from the ground. They work by having pipes buried underground filled with water and antifreeze. This mix absorbs heat from the ground and carries it to the pump. Similar to the ASHP, the heat is passed to a refrigerant, which is then compressed to make it warmer, with the heat generated being used in the home.
Because the underground temperature stays fairly consistent all year round, a ground source system has a steady heat source to draw on, even when we get those unusually cold Sussex winters.
The main difference is how they collect their heat. An ASHP uses air, whereas a GSHP uses the ground. However, there are considerable differences in costs, installation, running costs and more. The table below shows you the comparison at a glance.
| Air source heat pump | Ground source heat pump | |
| Heat source | Air | Ground |
| Installation/upfront cost | £8,000 – £15,000 | £15,000 – £35,000 |
| Running costs | £650-£870 per year (much lower than an old boiler, oil or LPG) | Typically lower than an air source heat pump |
| Efficiency | 3-4 SCOP | Higher and steadier through the year |
| Planning permission required | Not usually needed (permitted development in most cases) | Usually a permitted development. Ground loops may need permission |
| Lifespan | 15-20 years | Up to 25 years |
| Ideal for | Homes with more limited space | Suited for homes with a larger outdoor space |
| Space required | 2m x 1m and a hot water cylinder | Garden space for trenches or boreholes, plus an indoor unit |
| Noise | Can have some moderate fan noise | Near silent, no external fan |
| Eligible for boiler upgrade scheme? | Yes (£7,500) | Yes (£7,500) |
*Please note, prices are only estimates and will vary depending on the property size, the scale of work, the pump itself and current energy prices. *
An air source heat pump could cost between £8,000 and £15,000 to install, whereas a ground source pump may start at £15,000 and rise as high as £35,000. Ground source pumps typically cost more due to the level of work involved. Digging trenches and drilling boreholes, for example, is much more labour and time intensive than simply affixing a unit and carrying out some minor installation work.
Both heat pump types are eligible for the current Boiler Upgrade Scheme. This offers eligible homes £7,500 towards the cost of an air source or ground source heat pump. Homes heated by LPG or oil can have this grant increased to £9,000. We’ve compiled a guide about the boiler upgrade scheme so you can see whether it’s something you can take advantage of.
The running costs are normally lower for a ground source heat pump, thanks to higher efficiency. However, air source pumps can cost around £650-£870 per year in a typical home, representing a good saving against standard energy bills. Compared to older gas, oil or LPG systems, either pump will cut running costs considerably.
Ground source heat pumps are generally more efficient than air source heat pumps. A good air source heat pump delivers around 3-4 units of heat for every unit of electricity it uses. This gives it a seasonal efficiency of roughly 3-4, making it far more efficient than a gas or oil boiler.
A ground source pump will deliver higher efficiency than this in most cases, and it can maintain it throughout the year due to stable underground temperatures. An air source heat pump will still work in winter, but its efficiency can drop when temperatures get a little frosty. For exposed properties on Sussex farmland, for example, this could be a factor worth considering.
An air source heat pump needs much less space than a ground source heat pump. An outdoor unit can need as little as 2m x 1m and sit against an outside wall. For terraced homes or properties with small gardens, it can be the preferred choice.
A ground source heat pump, on the other hand, requires space for its pipework to be buried. You’ll also need indoor space for the heat pump unit and a cylinder. For homes with generous garden space, this isn’t necessarily a problem, but in built-up areas, an air source may remain the best choice.
Ground source heat pumps are the quieter of the two. They have no external fan, meaning they run close to silent. To function, an air source heat pump needs its fan to draw in air. As a result, there is some noise. However, modern units are much quieter. The noise is perhaps comparable to the hum of a fridge. It may seem relatively minor at first, but if it were close to a neighbour’s window, it could prove distracting.
There is no single correct answer. Everything boils down to your property, your budget and your plans.
An air source heat pump is perhaps best if:
A ground source heat pump might be a worthwhile addition if:
Property type comes into it, too. Across Sussex, we have many period and listed homes, and while air source heat pumps are normally classed as a permitted development, listed buildings need Listed Building Consent for a heat pump to be installed.
Still unsure about which heat pump might be best? Speak to our team. At Sussex Air Conditioning and Heat Pumps, we design and fit heat pumps for homes throughout the county. With over 20 years of experience and MCS accreditation, we are a trusted name for safe, reliable and professional heat pump installation and maintenance. Each system we fit is eligible for the Boiler Upgrade Scheme, and our team can walk you through the process to help you secure the grant. We’ll assess your needs, align them with your budget and factor in the property size to give you exactly what you need. Get a free quote today or give us a call on 01273 434586 for any assistance.
Are ground source heat pumps worth it?
For homes with the land and a long-term outlook, yes. The higher efficiency and lower running costs pay back over time, and the buried pipework is long-lasting. For smaller properties, an air source heat pump is normally the better investment.
Do air source heat pumps work in winter?
Yes. Air source heat pumps extract air even in cold weather. Their efficiency may drop when temperatures plummet, but a well-sized system will keep your home warm all year.
How long do heat pumps last?
An air source heat pump typically lasts 15-20 years, and a ground source heat pump can last as long as 25 years. Regular servicing helps both systems reach their maximum lifespan and perform much better.
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