Installing any kind of central heating system can be messy. This is because pipework tends to be concealed in difficult to access places where it can’t be seen, such as under floorboards and even in the walls. But once your heating system is in, you shouldn’t ever need to access the pipes - and radiators can be changed and boilers replaced without requiring too much work. But can the same be said for heat pumps?

Heat pumps work in a very different way to a boiler but luckily, your home’s current pipework should be sufficient for the heating system to warm the water and pump it round your radiators. However, the heat pump itself needs to be installed and the way this is done depends on the type of heat pump system you choose.

Which is the easiest heat pump to retrofit?

There are two main types of heat pumps - air source and ground source. An air source heat pump takes in warm air from outside whereas a ground source heat pump takes warmth from the ground.

Out of these two systems, an air source heat pump is the easiest to install in an existing home. This is because you shouldn’t require any planning permission prior to installation and the system can be fitted within a couple of days. As previously mentioned, you shouldn’t need any additional pipework or radiators to be installed, unless the suitably qualified heating engineer finds an unforeseen problem with your home’s pipes that may need to be addressed.

The unit for the heat pump can be installed on the outside of your home. This may cause some mess but it should be minimal.

A ground source heat pump is more difficult to install because the pipework needs to be laid in the ground and you may need a certain amount of space to be able to do it. This is why you must have the ground around your home surveyed to ensure that the installation can go ahead. If there isn’t enough space, the pipes can be arranged vertically instead of horizontally, but in order for your heat pump to work efficiently, the pipework may need to go quite a long way down.

 Can a ground source heat pump be installed under a home?

So, if you don’t have enough space for a ground source heat pump, can the pipes be laid underneath the house? The simple answer to this is no! The pipes should be laid a certain distance from your house. As mentioned previously, if you don’t have enough land for the system to be laid horizontally, boreholes can be created to install the pipes vertically. This keeps the surface area of the pipe system large enough so that heat can be collected from the ground and brought into your home.

How deep is a ground source heat pump?

If the pipework for your heat pump is installed horizontally, it will be around one to two metres below the surface. However, for a horizontal system to be installed, you would need around 200 to 400 m2 of land. The average house in the UK has a garden of around 90 m2 meaning for most people, a horizontal system isn’t possible. 

A vertical system goes far deeper than this, up to 150 metres below the ground, making these systems ideal for people with smaller gardens. However, this makes ground source heat pumps quite difficult and messy to install.

When do you install boreholes for a ground source heat pump?

Before the boreholes can be installed, there are certain checks that must be made first. A geological survey will be carried out to check that the ground and surrounding areas are suitable and you should see whether planning permission is required.

Once you’ve confirmed everything you need to, the pipework can be installed. This is likely to be done before the heat pump unit itself is installed and set up in your home as the pipes need to be pressure tested.

Once the boreholes are in and the pipes installed, everything can be connected to the heat pump unit. 

 Can you install a heat pump near a boundary?

Before your air source heat pump is mounted, it may be a good idea to check with your local council that you don’t need planning permission and that the location is suitable. It’s also worth noting that the heat pump must be positioned in such a way that its appearance is minimal and out of view of a road, and it must be below the first storey of your home.

In England and Scotland, for a heat pump to be installed the unit must be at least one metre from the property’s boundary. This rule differs in Wales and is extended to three metres.

There is also an MCS calculation which determines the potential air source heat pump noise nuisance to neighbouring properties in close proximity. If the noise level is too high then this may be rejected from a planning perspective.

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