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How Does An Air Source Heat Pump Work

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  • 27-09-2021
How Does An Air Source Heat Pump Work

This article looks at: how does an air source heat pump work? We discuss the benefits of air source heat pumps and why you might choose air source heat pump for heating.

What Is An Air Source Heat Pump?

In most cases, homes in the UK today employ heating systems that require the burning of fuels, such as natural gas, or electricity which they convert into heat. However, air source heat pumps work differently in the fact that they don't generate any heat at all. Instead, these systems take heat energy that exists outside of your home and brings it in. 

Heat pumps are, therefore, a very efficient and energy-saving system for heating your home. Compared to the electrical or chemical energy other heating systems use to generate heat, these heat pumps provide more warmth than the electrical energy they use when in operation, meaning they are cheaper to run than conventional heating systems.

How Warm Can A Heat Pump Get Your House?

The Benefits Of Air Source Heat Pumps

Air source heat pumps cost far less to run than traditional central heating methods. By replacing your traditional fuel or electrical heating system with an ASHP, you will dramatically cut down on your monthly energy bills. Additionally, as if this wasn't enticing enough, the UK government introduced the Renewable Heat Incentive (RHI) in 2011. 

Through this scheme, people are paid for the renewable heat energy that their heating systems produce. You will be given a fixed amount of money in RHI payments for each kW hour of heat energy that you make. Most of this heat will be used in your home, but you may receive more money for any surplus heat you produce if connected to a wider network. 

Of course, there are various ecological benefits of air source heat pump installation. They will help lower your carbon emissions compared to the fuels you previously used, providing a green heat source for your home. They are also very low maintenance, often referred to as "fit and forget" technology. Compared to other green heating systems, such as ground source heat pumps, they are also incredibly easy to install.

How An Air Source Heat Pump Works

A simple way to think of an air source heat pump system is as a fridge running in reverse. The outside air of your home is blown over a series of tubes containing a refrigerant liquid. This air then warms up the refrigerant, turning it from a liquid state into a gas. The refrigerant gas is then forced into a compressor. 


The gas is warmed up in the compressor to create heat energy for your home through increased pressure. You can think of this step in the same way that the air hose you use to fill the tyres on your car warms up as you use it. 

The higher the pressure in the system, the warmer the gas is going to be. This warm, compressed gas is then sent into a heat exchanger.

The heat exchanger surrounds the hot gas will cold air or water. The heat energy then transfers from the warm refrigerant gas into the colder air or water surrounding it. This warm air or water is then sent through your home's central heating system, providing you with the heating and hot water you need. At the same time, the refrigerant is allowed to cool back into a liquid to start the process again.

Air Source Heat Pump For Heating

For your air source heat pump to operate at peak performance, it is best when your home's outside and inside temperatures are closer together. Similarly, it is easier for your fridge to keep things cooler when the weather is cold, meaning it has to work far harder to keep your food refrigerated during the summer. 

This makes ASHP systems perfect when used together with underfloor heating. The surface area of the floors in your home is far larger than traditional heating appliances, such as radiators. This increased area means that they do not need to get as hot to provide the same heat as these smaller systems. 

However, one drawback is that these ASHP systems have a lower output than traditional natural gas or oil-fired boilers. This lowered output means they will not be able to heat your home as quickly as these more traditional systems. Air source heat pump systems are best used to heat your home gradually over longer periods than suddenly raising the temperature.

Air Source Heat Pump For Radiators

The lowered output of this system is demonstrated when converting your traditional radiator heating system to a new ASHP one. 

Given that they cannot provide the same amount of heat in the same amount of time, if you are converting your radiator system, you will need to buy larger radiators to get the same amount of heat as before.


Air Source Heat Pump For Hot Water

Air source heat pumps are also an excellent and energy-efficient way of generating hot water for your home. However, they cannot produce water as hot as a boiler can. Therefore, if you are thinking of running yourself a bath, you will need to use a larger amount of hot water to get the same effect. Additionally, larger hot water tanks will typically be needed when installing an ASHP system.

Is An Air-to-Water Heat Pump Right For Me? 

Air-to-water heat pumps can be installed on almost any type of home in the UK. They are also becoming an increasingly popular choice, with tens of thousands of homeowners across the country opting for these new greener heating systems. But, before you go straight ahead and order one for yourself, there are a few things you need to consider first.

Do You Have Enough Space For It?

To ensure the system runs properly, it must have enough space outside your home to generate a good airflow. You will need a bit of room outside for the system to be installed, either being fitted to the wall of your home or somewhere on the ground nearby. 

There are two types of heat pumps: monobloc or split systems. The first is a single unit that houses all of the necessary components. Pipes will run from the unit carrying hot water into your central heating system, with hot water cylinders installed inside your property. Split system ASHPs, as the name might suggest, separate the various components of the system between outside and inside units. 


Your budget and the available space for the system will determine which one is best for you. Monobloc units are often cheaper than split ones. They are also far easier to install, given that the components are all in one unit. 

They also do not take up too much space once they are installed. However, monobloc systems tend to be slightly less efficient than their split unit counterparts. 

Split unit ASHPs are far more efficient given that the heat transfer from the gas refrigerant to the air or water inside your central heating takes place inside your home, where it is naturally warmer. Therefore, if you have enough space and a little extra money, it may be worth looking at a split unit air-to-water system.

Is A Heat Pump Loud?

The outside units for both monobloc and split ASHPs are practically identical. The only noise generated by the system is from the fans used to move air over the heat exchanger. Therefore, when your air-to-water system is operating normally, it should be no louder than a fridge would be. Of course, if you are demanding higher temperatures from your system, the fans will naturally be a little louder. 

You would be able to hold a conversation standing next to the outside unit without raising your voice. However, if the outside air drops to lower temperatures, the fans will have to work harder. You should still be able to hear each other talk, though you may have to speak up a little. The inside units only contain pumps and valves and make no noise at all.

Will It Heat All The Rooms In Your Home?

UK homes typically use what is known as a "wet system" to heat their rooms. These include central heating systems that use radiators or underfloor heating. Air-to-water heating requires a wet system to heat your home, meaning if you do not have such a system in place, you will need to decide whether to install one or not.

However, if you do not have a wet system in your home, all is not lost. Installing one at the same time as your air-to-water system means you can optimise your central heating to work with these new ASHPs. This optimisation will ensure lower running costs and greater efficiency when heating your home.

Do You Have A Hot Water Cylinder?

Basic ASHPS cannot generate hot water on demand like a traditional boiler can. Therefore, you will need to install a hot water tank or cylinder to store the hot water for when it is required. How big the hot water cylinder needs to be depends on how much hot water your household uses, but they can typically fit into most cupboards. 

However, if your home lacks space, there are still ways to get around this issue. You can install a hybrid system, where the ASHP provides general heating while a boiler gives you hot water when you need it. Heat batteries are also an option, which will take up far less room than a hot water cylinder.

Are you considering air source heat pump installation in Essex, Suffolk and the surrounding areas? We have years of experience in providing tailored energy-efficient and affordable home heating solutions. So if you need any further assistance  with air source heat pumps, follow the link below.