Is An Air Source Heat Pump the Right Choice For My Home?

With the cost of living crisis it’s easy to see why everyone is looking for ways to save energy by reducing their electricity bills. Saving energy is a good reason why air source heat pumps (also known as ground source heat pumps) are becoming more popular. Added to this air source heat pumps are also seen as a less “polluting”, cleaner form of heating which could help the UK to meet its climate targets.

What Is an Air Source Heat Pump and How Does It Work?

An air source pump extracts warmth from the outside air and transfers it via a compressor into your home to supply central heating and hot water. In essence an air source heat pump works like a refrigerator in reverse:

• Air from outside is pumped/moved across tubes filled with refrigerant.
• The air warms the refrigerant and turns it from a liquid into a gas.
• The gas then passes through a compressor which increases the pressure of the gas compressing it.
• The compressed gas which is hot passes into a heat exchanger which is surrounded by air or water.
• The refrigerant then transfers the heat generated to the air or water making it warm which is then used to provide heating or hot water.
• The refrigerant then condenses back into a liquid and the process starts over again.

Air source heat pumps will work even when temperatures are below zero. However, they work better when the difference in temperature outside is closer to the temperature inside. A smaller temperature differential makes it easier for air pumps to perform at their best. This is just like a refrigerator or air conditioning system which has to work harder in hot weather to keep the inside cool.

It's also important to note that air source heat pumps have a lower output than standard oil or gas fired boilers so they don’t deliver heat as quickly and radiators won’t get as hot (and the hot water supplied will be warm rather than hot). It’s therefore best to look at air source pumps as a way to heat your home and water slowly over a longer period of time.

Just How Efficient Are Air Source Heat Pumps?

Heat pumps are more efficient than other heating systems as they are able to provide more heat energy than the electrical energy that they use.

The efficiency of a heat pump and the amount of heat it produces is measured by its Coefficient of Performance (CoP). Air source heat pumps can have a CoP as high as four. This higher the CoP the more efficient the heat pump is. A heat pump with a CoP of four produces four times the number of units of heat for every unit of electricity it consumes. In comparison electric heaters work at around 100% efficiency meaning they use one unit of electricity to produce 1 unit of heat; a gas boiler works at 90% efficiency but is around two thirds cheaper than electricity. As a consequence, an air source heat pump must be at least 300% more efficient to be able to compete against electrical and gas heating systems.

The CoP gives you a starting point in determining an air source heat pumps efficiency but it’s also important to take into account the Seasonal Coefficient of Performance (SCoP) or Seasonal Performance Factor (SPF). The SPF looks at year-round conditions and the differences in temperature experienced throughout the year and will help in understanding what the ongoing, year-round cost of running a heat pump will be. Your heat pump installer should calculate the SPF based on the design of your system and share this with you before work begins. Based on the CoP and SPF you will then have a better indication of what your running costs will be.

How Much Will an Air Source Heat Pump Installation Cost?

An air source heat pump installation will cost more than a gas or oil-fired central heating system, in the short term. The cost depends on the brand of the heat pump used, the size of the home/installation, whether underfloor heating is being installed, if your current radiators are large enough or need to be replaced and if insulation is required. It’s therefore difficult to provide a cost estimate until your home has been surveyed and installation requirements are determined.

You can get a government grant towards the cost of your air source heat pump installation if you qualify. The Boiler Upgrade Scheme offers up to £5,000 towards air source heat pump installations. The scheme will run for three years but is currently limited to 90,000 homes.

What Does It Cost to Run an Air Source Heat Pump?

Energy prices continue to vary, especially given the current energy crisis and rises in the costs of electricity and gas. Homes differ in size and air source heat pump installation requirements will also differ from home to home therefore it’s difficult to give an exact figure regarding how much it will cost to run a heat pump.

The Energy Savings Trust provide information on the potential annual savings that you can expect from installing a standard air source heat pump in an average sized, four-bedroom detached home. These figures are based on fuel prices as of April 2022 and show the prices expected between old and new system heating system replacements. Savings will also depend on the size of your home, the fuel type that is being replaced and whether a heating system upgrade or insulation is required.

The EDF website outlines some figures on the costs of running an air source heat pump in comparison to gas, oil and LPG heating, based on the energy costs given on the Energy Savings Trust website.

They also outline at the example of what it would cost a modern four bedroomed house utilising 19,000kWh of heat per year, although they do make it clear that although this estimate is based on industry wide figures it is just an estimate as an exact figure is not possible given that they are having to make assumptions which limits the calculation involved. 

What Type of Air Source Heat Pumps are Available to Me?

There are two types of air source heat pumps which work on the same principle of heat transfer. These are air to air and air to water. The majority of air source heat pump installations are air to water in the UK, with a minority of installs suitable for air-to-air heat pumps.

Air-to-Water Air Source Heat Pumps

Air to water heat source pumps transfer the outside heat to a traditional wet/water heating system. The air to water air source heat pump is ideal for new builds or for homes where boilers can be replaced with a high temperature heat pump. They can also be connected to solar energy, underfloor heating, radiators to provide central heating and a heat pump convector. It can also be used to heat water to be stored in a tank or hot water cylinder to be used for baths, washing etc.

Air-to-Air Air Source Heat Pumps

The alternative to the air to water heat pump is the air-to-air system. These systems transfer the heat from outside into the air inside. Air to air systems are more commonly known as air conditioning systems and provide cooling and heating but don’t provide hot water.

There is also the option of a hybrid air source heat pump which can be used in conjunction with an existing boiler and central heating system. The hybrid system is ideal for renovations or old gas boiler replacements. It can also be used to connect to an existing gas boiler as add-on solution. In a hybrid system the heat pump usually supplies a “base” load for day-to-day heating and hot water where the boiler is used to top up the hot water requirements when needed or to provide a boost on colder days.

What Are the Advantages and Disadvantages of An Air Source Heat Pump?

In order to decide if an air source heat pump is right for you it’s worth considering the following advantages and disadvantages:

Advantages

• Air source heat pumps have a high CoP making them very energy efficient.
• As a result of their high CoP, they are usually more cost effective than other home heating systems.
• Air source heat pumps have a good lifespan and require low maintenance.
• They are easier to install than ground source pumps.
• Their low or zero carbon footprint (if used with a renewable energy tariff) is good for the environment.
• Installation costs can be offset by the UK government’s boiler upgrade scheme.

Disadvantages

•  Some homes especially flats are not suitable for air source heat pumps given the space needed for the installation.
• They will only work at temperatures of minus 15°C and lower however energy efficiency decreases the colder it is outside and in colder temperatures more electricity will be required.
• Radiators will feel warm, not hot, as air source heat pumps supply lower heat than boilers, so homes will take longer to warm.
• Your home needs to be well insulated to keep the heat in.
• Air source heat pumps can be noisy so its best to site your pump at a distance from your home.

What To Do Next Having Decided an Air Source Heat Pump Is Right for You?

Once you’ve decided that an air source heat pump is right for your home what’s the next step and how do you ensure that you get the most out of your new heating system?

Finding the Right Installer

When it comes to the installation you’ll want to ensure that you find the right air source heat pump installer.

It’s important that your installer understands the technology and how to ensure your installation gives you the best return for your investment in terms of installation and running costs. In order to do that the installer needs to have a clear understanding of how low temperature heating systems work, the requirement and workings of the required control system as well as which brand would work best for your home and what design will give the best results.

It's also a good idea to get a quote which covers the following: what will be covered as part of the install e.g. will the price cover radiator upgrades if required, is integration with your existing system included if required, will removal and safe disposal be included if any system components need to be replaced; will the cost cover the commission of the system, will the installer carry out the whole job or do they sub contract or will other trades be required to complete the work, will the installer provide the efficiency values of the system and what payment plans are available to you and are they covered by insurance? 

Understanding Your Air Source Heat Pump System

Once your system is installed it’s important to understand how it works, to ensure you are getting the best out of the system. Take the time to understand your heating controls and how to use them effectively. Refer to your system’s user manual and ensure your system is setup to give you the level of heating and hot water that best suits your needs in line with your daily routine. 

The harder an air source heat pump has to work the more electricity it will use. Air source heat pumps also need longer to heat your home so set your pump to supply heat at a lower temperature over a longer period of time so that your home is warm when you need it to be while energy consumption is kept as low as possible.

When you have your heat pump system on close your windows and doors to ensure the heat generated does not escape through an open window. It’s also important to ensure you have good insulation so that heat is not lost.

Check that your external unit is not blocked by debris e.g., leaves and remove any items that may obstruct the unit including plants or snow and ice during the winter months.

Maintaining Your Air Source Heat Pump

Just as with any mechanical and electrical system its vital to maintain the system and service it on a regular basis so that any issues or faults are found and corrected as quickly as possible and the system continues to work effectively and efficiently.

Synecore

Synecore is a residential air source heat pump installer in Kent, London, Surrey, Sussex, Essex. We can advise on the right system for you, then design and install your home air source heat pump system. We provide installation of high-quality products from leading manufacturers.

Synecore’s air source heat pump experts will complete a survey of your home to determine your specific needs. To book a free survey, please contact Synecore on 01795 509 509. Our team will book an appointment for one of our engineers to visit your home and discuss your options.