Are Air Source Heat Pumps Worth It in the UK?
The answer to this question is more complicated than a simple ‘Yes’ or ‘No’ but, generally speaking, an air source heat pump is definitely worth it if your home is suitable.
What makes a home suitable for an air source heat pump?
Well, in this blog we’ll take a look at what an ASHP is, where they can be installed and whether or not they are worth the investment.
What Are Air Source Heat Pumps and How Do They Work?
An air source heat pump works in very much the same way an air conditioning unit does, but with the results reversed.
They way the work is as follows:
Air is drawn from outside:
The most visible part of an ASHP system is the fan that sits on the outside of the property. This fan draws air in and feeds it into the system.
‘But, where’s the heat in outside air during the British winter?’ I hear you ask.
Well, it’s there, believe it or not – a heat pump will heat your home even when the outside temperature drops to -15°C … sometimes below -22°C!
Air source heat pump evaporation
The air comes into an area called the ‘Heat Exchange’. This area is filled with refrigerant, the same stuff in the back of your fridge.
Refrigerant has a very low boiling point and the heat from the air makes it expand - becoming a low-pressure gas.
This process is called Evaporation.
The next stage is Compression:
The heated refrigerant gas is then compressed further to create friction and, as a result, heat.
Condensation transfers the heat
Inside the condenser are pipes filled with water that cool the refrigerant gas.
This moves the heat from the gas to to the water.
Expansion
The final stage is passing the refrigerant through an expansion valve, lowering the pressure and absorbing more heat energy.
It is then pumped back into the heat exchange to repeat the cycle.
The UK Climate: Is It Suitable for Heat Pumps?
It sure is!
In fact, air source heat pumps are incredibly popular in Scandinavian countries, which have much more extreme weather than us.
An air source heat pump will work between minus 20 degrees and plus 40 degrees - if we are reaching those kind of temperatures with any regularity we’ll have more to worry about than ASHPs!
Last time England recorded a temperature that low was 1982 – so you can be sure that your heat pump will be working fine all year round.
The relatively mild nature of the UK’s climate means it’s pretty much perfect for ASHPs.
Government Grants and Incentives in the UK
There are many local and national grant schemes for upgrading the tech in your home for something a little greener.
When it comes to air source heat pump grants the main one is the Boiler Upgrade Scheme or B.U.S.
B.U.S. has been created so homeowners in England or Wales can get up to £7,500 towards the installation of an air, or ground, source heat pump.
This grant is open top almost everyone and knocks a substantial chuck off the price of replacing your gas boiler.
You can only get the B.U.S. grant if you are upgrading a current, fossil fuel boiler.
The ECO4 Scheme is still available until 2026 and provides financial assistance to low-income households in England, Scotland, and Wales that need to improve the energy efficiency of your home.
Reduced VAT is kind of like a grant, yeah?
Well, the VAT on renewables has been dropped to 0% until 2027 to encourage up-take with the public.
This is only available on installation, rather than the products themselves.
Warmer Homes Scotland is an interest-free loan scheme available to homeowners in Scotland.
They an borrow up to £10,000 to install energy-efficient energy systems.
Also in Scotland is the Home Energy Scotland Scheme.
Again, it’s a loan: You can receive an interest-free loan of up to £15,000.
The Welsh can get in on the Nest Scheme, Wales.
This offers free, impartial advice to all households in Wales to help reduce energy bills, maximise efficiency, and lower carbon footprints.
If you are in a qualifying low income household, you can get the full cost of installing an air source heat pump covered.
Installation Requirements and Considerations
Now, an air source heat pump isn’t suitable for every home – but they are suitable for most homes.
Any reputable installer will ensure your home meets all the requirements needed to run an air source heat pump efficiently.
Your home must be:
- Well Insulated
- Have suitable radiators
- Have a suitable water heating system
- Space to mount/sit the fan unit
- Space for the indoor units
- Double glazing
If your home isn’t ready, it may be worth improving it anyway – a well-insulated home will always be cheaper to run.
Running Costs and Efficiency Compared to Gas Boilers
This is an area of debate filling up renewable message boards over the UK right now.
Air source heat pumps are much more efficient than gas boilers, producing 400% of the energy they consume.
The confusion comes from the fact that gas is way cheaper than electricity in Britain.
So, it’s hard to work out the actual running cost of an air source heat pump in comparison to a gas boiler – but we’d say they fall within similar over all running costs, but the ASHP is actually using less energy.
You can also search for a suitable SEG from your energy provider to save a little extra cash.
Environmental Impact and Carbon Savings
Not always the first thing people think about when installing any kind of renewable tech, believe it or not.
Most customers who fit ASHPs or Solar are looking to save money, first and foremost, so don’t feel guilty if that's is your motivation.
The side effect of this money saving is, of course, the reduction in carbon use all over the nation.
So, what are you saving?
Well, British Gas have done the work for us here. According to their research, an average UK Household will consume around 12,000 kWh of energy a year.
If that household has a gas boiler it will be pumping out over 2,500 kg of CO2 per year.
An air source heat pump produces just 850kg of CO2 per year - but the amount of CO2 you save will depend on you actual energy use AND how you are powering your home.
Common Misconceptions About Heat Pumps
Let’s take a quick look at some air source heat pump myths:
They don’t keep homes warm enough
A journalist from the Daily Telegraph when he said “you can’t find an engineer prepared to install one of the devices in your home because, in all honesty, they know it wouldn’t actually keep you warm.”
Well, we fit 100s a year, so we know the guy is speaking rubbish.
If your home is suitable for an ASHP, that ASHP will keep you toasty and warm.
Air source heat pumps are very noisy
To be fair, the fans in a heat pump can make a noise but it’s usually less than around 40 decibels – which is the same as your fridge.
As tech improves, they are getting quieter too.
They are hard to install.
They really aren’t, certainly not if a qualified installer is on the job.
They do take longer than a solar energy system or having and EV charger fitted, but there are many more components to think about with an air source heat pump.
The average install can take a couple of days, but the fitting team will ensure there is no interruption in your heating and hot water.
They are only good enough for a new house
While a new home is much more likely to be built in a way that makes them ideal for an air source heat pump, that doesn’t mean older homes aren’t also suitable.
If your home is well insulated, has double glazing, and doesn’t have its roof missing, it’ll be fine for an air source heat pump.
If you need proof ASHPs are fine in older buildings, check out the church in Lympne, Kent – it was built in the around the same time as the Battle of Hastings and it’s parishioners are currently staying toasty due to the heat pump they have.
They won’t work during a power cut
Nothing electrical works in a power cut – unless you have a gateway on your solar energy system.
If you do, then your ASHP will work in a power cut!
They’re more expensive to run than gas boilers
An ASHP is 4 times more efficient than a gas boiler.
That said, they are supposed to run at a constant temperature so they can be a little more expensive if you keep cranking the heat up.
But, much like a cruise control on a car, if you’re not messing with the ‘speed’ all the time, your car will burn less petrol.
ASHPs are way more economical than electric heating, especially if you have fitted solar as well.
You can’t have an air source heat pump in a flat.
You absolutely can.
In fact, if you see a box with a fan in it on the side of a building in the UK, it’s probably an ASHP – and you see plenty on flats and commercial businesses.
The mounting of the external box is probably the most difficult part of installing an ASHP in a flat that’s not on the ground floor.
You need a backup when it’s cold.
Not in the UK as, in this case, cold means ‘absolutely freezing!’.
In some of the more northern Nordic p[laces, ASHP may have a small electric heater in them to ensure the fan and other internal parts can still move.
The last time England recorded a temperature low enough to trouble an air source heat pump was a chilly -22 in 1982.
Air Source Heat Pumps are a nightmare to maintain and repair
Again, no.
ASHPs are basically a fan, some pipes of varying sizes and some refrigerant.
In comparison a gas boiler has all sorts of complicated bits n bobs to keep the gas in and not in your home exploding anything.
Your installer will tell you what needs replacing and when – so long as you keep up with the low amount of maintenance you need monthly, your ASHP will be good for years.
So, are Air Source Heat Pumps worth the money?
Well, we’d say so:
- Efficiency – Yes
- Low Carbon – Yes
- Reliable – Yes
- Toasty Warm – Yes
TBH, if your home is suitable for an air source heat pump, you’d be doing yourself a favour if you fit one next time your boiler needs upgrading.
