Page written & correct as of: 01/11/2023.
Introduction to Air Source Heat Pumps
So, you’ve decided an air source heat pump is a good fit for your home. It’s a great idea, we love them. They don’t burn fossil fuels, creating carbon-based emissions during use and could be used alongside photovoltaic (PV) panels to provide you with completely free (after installation) heating and hot water.
Plus, great news, there’s a government grant available of £7,500 to help you pay for it. If you would like to get a quote for an air source heat pump, please contact us on 029 2009 9898 and we’ll be happy to have a chat.
We are a Viessmann premium supplier. We work with Viessmann because of their quality manufacturing processes and industry-topping long warranties on products.
Let’s begin…beware, there is a lot of misinformation out in the world.
Air source heat pumps work best, and very well, in specific conditions at well insulated homes. They need to be set up correctly to ensure their high efficiency. If they’re not set up right they can cost you a lot of money by working harder than they should and this could also shorten lifespan.
We’ve tried to create a detailed and honest guide to answer all your questions surrounding what is and isn’t possible with air source heat pump installations. We’ll need to go through the heat pump units, the pipework, the radiators, insulation and more.
Please bear in mind that all homes are different and will have slightly different set ups and requirements.
Each of the below steps is something you will need to consider when thinking about highly energy efficient air source heat pump installations.
MCS (Microgeneration Certification Service)
MCS is a standards organisation that maintains and improves quality by certifying low-carbon energy technologies and contractors. They have strict rules to ensure that the heat pumps work to their specifications and are as energy efficient as possible.
Without MCS sign-off you will not be able to get the £7,500 grant after installation. They look after the following:
The grant amount should be subtracted from your initial quote, and it’s normally the installer’s responsibility to extend the discount from the BUS grant to you as the property owner.
Air source heat pumps run at lower temperatures than traditional gas, LPG or oil boilers. This keeps them highly efficient. But it means you may not be used to the slightly different way the system works day-to-day.
Heat Loss Survey
The heat loss survey aims to gather all necessary information to design an efficient and cost-effective heat pump system tailored to your property. During a heat pump survey, the surveyor will focus on several key areas:
An Energy Performance Certificate (EPC) provides details on a property’s energy consumption and offers suggestions for reducing energy use and costs giving a ‘potential’ score. It is mandatory whenever a property is bought, sold, or rented.
Before approving any grant applications, the property’s EPC is verified to ensure it was issued within the last decade and contains no recommendations for loft or cavity wall insulation. EPC reports are not checked for eligible self-builds.
If there are any recommendations for loft or cavity wall insulation an air source heat pump won’t be eligible for the grant until this is sorted. Once sorted, you can get another EPC survey completed and submitted. This new EPC report must not then have insulation recommendations.
Check your EPC here > https://www.gov.uk/find-energy-certificate
In order to get the heat from the heat pump into and around your home the system needs to pump a high flow of water at approximately 40 degrees centigrade. This is otherwise known as Delta 40.
To allow this high flow around the system you will need to have at least 15mm into and between all the radiators and 22mm pipe from the heat pump itself. This means that if you have 10mm pipes feeding any of your radiators you will need to upgrade those pipe runs for as long as they’re 10mm.
The cost of a whole-house repipe depends on a lot of factors like the size of your house and where the pipes run. It could range from approximately £4,000 to £12,000. Of course you may not need a whole-house repipe.
Alongside the pipes needing to be thicker, you may need chunkier radiators in order to allow heat into the room.
A lot of people will have seen, or know about the double panel double fin radiators, also known as Type 22. In older, less insulated properties you may also need to replace these with larger, triple panel triple fin radiators that will work with the lower temperature water.
As already discussed, you will also need a hot water cylinder for your hot water taps and shower(s). If you already have one, the survey will note if it’s compatible. If it’s not then you will need a new one. If you don’t have one, maybe because you currently have a combi boiler, space will need to be made available. Ideally as close to the air source heat pump as possible.
If the external heat pump unit is not being wall-mounted it will require a solid base to sit on. This may require a concrete pad or something sturdy to hold it down to stop them becoming damaged.
You shouldn’t need planning for an air source heat pump. There is a section of the planning regulations or permitted development rights (PDRs) called ‘Class G’. According to Class G, you don’t need planning permission to install an air source heat pump on a house, bungalow, or block of flats. However, there are specific conditions and restrictions:
Distribution network operator (DNO)
DNOs are the companies who look after the physical network that transfers power and gas around the country. There are a few of them, but they are not the company that you buy the power from. There are also a number of Independent DNOs who can work on the network too.
Why are we talking about DNOs? Because full air source heat pumps need authorisation from your region’s DNO in order to be installed, wired in, and turned on.
But, why? It’s to do with the Amp capacity of the network in your area. Some local networks could be chained (where power may come to your property but then go straight to your neighbour). Another issue is that the heat pump’s compressor can create ‘noise’ in the infrastructure, like an electrical vibration, which could affect people within the local network.