Everyone seems to be talking about heat pumps these days!
This isn't surprising, as more consumers are looking for ways to reduce energy bills and lower their carbon footprint.
Sadly, however, not everyone is convinced that heat pumps are worth investing in, mostly due to misunderstanding and misinformation.
Well, the Heat Pump Gang team is on a mission to change all this. Our blog series, all about heat pumps, aims to lay out the facts and destroy the myths. Armed with helpful information, you'll be able to decide for yourself whether it's a wise investment.
In today's blog, we're looking into a little-known benefit of air source heat pumps: their ability to act as air conditioners!
So, is this a thing? And if so, how does it work?
That's what we're here to find out!
First things first: Let's examine the inner workings of the air source heat pump to understand how it functions before we investigate its potential as an air conditioner.
Air source heat pumps work in a similar way to the fridge in your kitchen but in reverse.
Instead of pulling warm air out and replacing it with cold air, heat energy from the outside air is drawn into the outdoor unit using a fan. A liquid refrigerant inside an evaporator coil absorbs the heat from the air and turns to gas, even in very low air temperatures!
A compressor squeezes the gas, raising its heat even further. The gas is pumped through to a condenser, where the heat exchanger releases the heat into the system. The gas then condenses back into a liquid and is pumped out to the expansion valve and back to the evaporator coil, where the process is repeated.
Before we move on, it's vitally important to know that there are two different types of air source heat pumps...
With this model, the heat is transferred to water, which is then pumped around your home to warm your radiators or underfloor heating – keeping you toasty in winter.
These work in a similar way, but instead of heating water, they directly heat the air inside your home. They use the same principle of extracting heat from outside air with the refrigerant, but this time the hot refrigerant is used to warm up air that's blown through the unit, circulating warm air throughout your house.
Why is this so important?
Because, technically, only one of them can take the place of air conditioning!
When the summer temperature gets a little uncomfortable, some air source heat pumps can be switched to cooling mode, effectively switching the system into reverse gear, just like a car.
This is how it works...
In heating mode, the air-to-air heat pump acts like a heat extractor, pulling warmth from the cooler air outside to provide heating for your home. In cooling mode, the tables are turned using the unit's reversing valve. The system now targets the warm air inside your home. Imagine a sponge – in heating mode, it absorbs cold water (outside air) to make your bath warm. In cooling mode, it soaks up the warm water (indoor air) to cool you down.
The key player in this process is the refrigerant, a special liquid that can easily change state between a liquid and a gas. As the cool refrigerant circulates through the evaporator coil located inside your home, it acts like a magnet for heat. The warm indoor air passing over the coil transfers its thermal energy to the refrigerant, causing the refrigerant to absorb the heat and cool down in the process. This is what makes the air feel less stuffy and cooler as it passes over the coil.
Once the refrigerant has absorbed heat indoors and become cool, it travels to the compressor. This clever component acts like a pump, squeezing the refrigerant under high pressure. Just like when you pump up a bicycle tyre, this compression process has a surprising effect – it actually makes the refrigerant much hotter!
The now-hot refrigerant makes its way to the outdoor coil, which essentially functions like a radiator in reverse. A fan blows outside air over the hot coil, and just like heat from a car engine is released into the surrounding air, the heat absorbed from your home by the refrigerant is transferred to the outside environment. This hot refrigerant acts like a shuttle, carrying unwanted heat from inside your home and dumping it outdoors.
Finally, the cooled-down refrigerant returns to the evaporator coil inside. A fan within the unit then blows cold air from the evaporator coil back into your home, creating a refreshing breeze that helps to lower the overall temperature. It's like having a personal air conditioner constantly circulating cooler air throughout your living space.
Here's the important bit again: this only really works with air-to-air heat pumps!
While air-to-water heat pumps are great at providing heating and hot water, they can't directly function as air conditioners (at least, not easily) for a few key reasons:
Air-to-water heat pumps are specifically designed to extract heat from outside and transfer it to water. Their internal components are optimised for this heating function. They lack the additional components needed to distribute cooled air throughout a living space.
The heat extracted from the outdoor air is used to provide hot water, not to heat air directly. This hot water is then circulated through radiators or underfloor heating systems to warm your home in winter. There's no built-in mechanism to cool the air itself.
Discover: Do Air Source Heat Pumps Work In Winter?
Unlike air-to-air heat pumps, which have indoor units with fans, air-to-water heat pumps don't have these components and, therefore, wouldn't be able to effectively circulate cold air even if they could produce it.
However, there is a way to get around this situation...
Although air-to-water heat pumps cannot directly cool your home, there's a way to achieve a cooling effect with additional components.
Adding a chilled water system with fan coil units in each room can make use of the air-to-water heat pump's reversed operation. The heat pump would then produce chilled water that would circulate through the fan coil units, which act like mini air conditioners. These units would extract heat from the room air and transfer it to the chilled water loop, providing a cooling effect.
Even so, this system is complex and expensive to set up - probably more so than a standard air conditioning unit.
If you want a highly efficient heating system, you can't really go wrong with air source heat pumps.
However, if you'd like year-round comfort, with an energy-efficient cooling system and space heating, then air-to-air heat pumps are your best bet.
Still need convincing? Then there are some plus points to persuade you!
Compared to traditional air conditioners, ASHPs excel in energy efficiency, using less electricity to cool your home than a conventional AC unit. This means lower energy bills, especially during peak summer months.
Explore: Air Source Heat Pump Cost
Since ASHPs rely on transferring existing heat rather than generating it through electricity, they have a smaller carbon footprint compared to traditional air conditioning. This makes them a more eco-friendly choice for cooling your home.
The beauty of an ASHP system (air-to-air) is its versatility. With a single unit, you can enjoy both efficient heating in winter and air conditioning in summer. This eliminates the need for separate heating and cooling systems, saving space and simplifying your home's climate control.
Most ASHPs come with user-friendly controls, allowing you to easily adjust the temperature and set comfortable cooling schedules. Additionally, some models offer features like multi-zone control for customized cooling in different areas of your home.
In the interests of full disclosure and fairness, we should also mention the following considerations:
Overall, installing an air-to-air ASHP for air conditioning offers a compelling solution for homeowners seeking energy-efficient, eco-friendly comfort throughout the year.
As we know, ASHPs are amazingly energy efficient. With a COP of 3 or even 4, they can deliver significantly more heat output for every unit of electrical energy used compared to traditional boilers.
But what does this mean in terms of your energy consumption? In short, how much will you save, and how soon?
Since ASHPs rely on electricity, the current electricity prices in your region play a crucial role. Currently (as of May 2024), the average electricity price in the UK is around 24.5 pence per kWh (p/kWh). Gas prices, on the other hand, are typically higher, averaging around 10.3 p/kWh (although it's important to keep in mind that these prices can fluctuate!).
However, efficiency translates to cost savings only when considering actual energy consumption. How often and for how long you use your heating or cooling system significantly impacts your running costs.
It's worth shopping around, as some energy providers offer time-of-use tariffs with lower electricity prices during off-peak hours. Scheduling your ASHP usage for these periods can further optimise running costs.
Replacing your oil or gas boiler with an air source heat pump is a fantastic way to reduce your environmental impact and lower your energy bills.
While it requires a significant investment, the Boiler Upgrade Scheme (BUS) provides £7,500 towards heat pump installation costs, making this a practical option for many thousands of UK homes.
The BUS grant is only available in England and Wales, although those north of the border can take advantage of a similar scheme run by Warmer Homes Scotland. Incidentally, this grant can be used for ground source heat pumps, too, but not hybrid heat pumps - it's strictly limited to renewable energy systems that replace fossil fuel burners, like oil and gas boilers.
In closing, let's summarise the main points...
Air source heat pumps are clever, doubling as efficient heaters and coolers!
While ASHP efficiency might dip slightly during scorching weather, they excel in both heating and cooling, offering a sustainable and cost-saving solution for year-round comfort.
When you want to take advantage of this amazing technology and enjoy the many benefits it offers, Heat Pump Gang will find the perfect heat pump for your home.
Check out: Advantages And Disadvantages Of Air Source Heat Pumps
