Everything you need to know about heat pump installation

Switching to a low-carbon heat pump is a bit more complex than just upgrading your old boiler with a newer one. Heat pump installation usually takes about five days – and this article takes a closer look at what typically happens during the installation project.

How to install a heat pump

If you’re thinking about getting a heat pump installed in your home, there are three main steps.

Step 1: Book a free home survey

Heat pumps work differently to gas boilers, creating a steady supply of medium heat rather than quick bursts of high heat. That means not every home is suitable for a heat pump – and some homes need a bit of extra work to get a heat pump working as well as possible.

At British Gas, every heat pump installation project begins with a free home survey carried out by one of our experts. We’ll take a couple of hours to look at your home and your current heating system, then recommend the perfect heat pump set-up for you.

And if we don’t think a heat pump is the right heating solution – because your home isn’t well insulated enough, for example – we’ll talk you through the alternatives we can offer, like the latest energy-efficient boilers.

Step 2: Get your fixed-price quote

After the survey, we’ll give you a fixed-price quote that includes everything you need to get going with a heat pump.

We’re confident that you won’t find better value on your heat pump installation. If you do find a lower quote for the same work from another accredited installer, just share the paperwork with us and we’ll offer the same price. That’s our Price Match Guarantee.

If you qualify for the £7,500 government grant (available in England, Wales and Scotland) we’ll include this in your quote. We’ll also explain the different financing options available, which can help you spread the cost into manageable monthly payments.

Once you accept the quote, we can start planning the installation itself.

Step 3: Installing your heat pump

Every home is different – and so is each installation project. Most of our heat pump installations take five days, but this will depend on your property. Some customers just need a little bit of work to make the change from boiler to heat pump, but others need things like bigger radiators, new pipework, or better insulation.

In the next section, we’ll explain what’s involved in more detail.

What exactly happens during heat pump installation?

There are a few different elements to the installation of your air source heat pump. We’ve separated them out and explained what happens for each. But in reality, a few of them might be going on at the same time.

Installing and plumbing the heat pump unit

Before the installation, your surveyor will discuss the best place to put the heat pump unit, usually at the back or side of the house. The unit typically measures 2m by 1m (imagine two washing machines side by side) and needs enough space around it for the air to circulate freely.

The heat pump has rubber feet and sits secure on level ground. Sometimes it can be hung on a wall, but this is subject to survey. Once the heat pump is in place, we install the pipework that connects it to the hot water cylinder and radiators.

Upgrading your pipework

During the survey, you might be told you need changes to your home’s pipework. This will all be completed by your team during the five-day installation.

You’ll need upgrades to your pipework if your existing pipes are too narrow to handle the faster flow rates and higher water volume of a heat pump – especially if more hot water needs to be sent to that part of the property.

Replacing your radiators

Heat pumps provide steady quantities of heat between 35°C and 55°C, rather than the quick blasts of 70°C to 80°C heat supplied by gas boilers. This helps make them more energy efficient, but it also means that they work best with radiators with a larger surface area.

A common part of an installation project is replacing your existing radiators with larger ones. The size of the radiator depends on the heat requirement for that room – and the cost is included in your fixed-price quote, so there are no hidden extras to worry about.

What about underfloor heating?

If all or part of your home has underfloor heating, we’ll check a few details to make sure it’s fully compatible. But generally, connecting underfloor heating to a heat pump is a straightforward process – and it means a lower overall price for your installation too.

Installing your new water cylinder

Once your heat pump is in place, we’ll install your new water cylinder – unless your survey found that your current water cylinder would work well with a heat pump. The cylinder is about the same size as a large fridge freezer.

Removing your old boiler

We’ll responsibly dispose of any parts of your old heating system that you no longer need, as part of your fixed-price quote.

A lot of people no longer need a gas connection when they make the switch to a heat pump. If that’s the case for you, we’ll cap your old supply and make it safe.

Updating your electrics

Unlike gas boilers, heat pumps are powered by electricity. Heating your home with a heat pump will increase your “electrical load”, which is the amount of electricity that flows into your home. One of your installation team will be a qualified electrician who’ll take care of this important side of the work.

We’ll give you new cabling, a new fuse box (also called a consumer unit) and new controls as part of your fixed-price quote.

Testing and fine-tuning your heat pump

The final part of the installation project is sometimes called “commissioning”. This is when your engineers finish testing and setting up your heat pump, to make sure everything in the system is working perfectly.

Once it’s all up and running as it should be, you’ll be shown how to use everything. And we’ll make sure you know who to contact if you have any questions or problems further down the line.


Frequently asked questions

How long does heat pump installation take?

Most British Gas heat pump installation projects take five days to complete. We usually schedule these for Monday to Friday, to avoid disruption to your home over the weekend. Five days is just an average, however – more complex projects might take a little longer.

Who will be on the heat pump installation team?

We usually have four people on the installation team – three heating engineers and one electrician. One of the heating engineers will be the lead engineer. They’ll oversee all work, be your main point of contact, and answer any questions you have.

How much disruption will there be during the heat pump installation?

We often warn people to expect ‘medium level’ disruption for the week.

Installing a heat pump is a bigger and more complicated project than installing a gas boiler, which is usually wrapped up within a day. Having a four-person team working around your home for five days does mean normal life is going to be disturbed quite a bit.

But it’s not the same level of disruption as you’d expect from a building project like an extension. And your lead engineer will be able to explain what’s happening where and when, so you shouldn’t find things too difficult.

How long will I be without hot water?

The longest you can expect to be without hot water is one day – although we can often find a way to make sure there’s no interruption at all. For example, we might be able to use an immersion heater on your cylinder to keep things working while we get the heat pump set up properly.

Can you replace a gas boiler with a heat pump?

Yes, absolutely. Most of our installation jobs involve swapping a gas boiler with a low-carbon heat pump – and then making the necessary changes to the rest of the home’s heating system.

Can you install a heat pump yourself?

Installing a heat pump is a fairly complex job that requires a range of technical skills – including electrical and plumbing. Unless you are a certified heat pump engineer, you shouldn’t attempt installation yourself, or you risk damaging your property and even injuring yourself.

Can heat pumps be installed in flats?

It is technically possible to install heat pumps in flats, but it’s more complex than in houses – and we don’t currently offer this service. One extra complication is that leaseholders need permission from the freeholder to place a heat pump outside, which can be difficult to get. Also, the heat pump needs to be situated far enough away from neighbours’ windows to stay within planning permission rules, which can also be quite tricky to manage.

Can air source heat pumps be installed indoors?

Yes, heat pump units can sometimes be installed indoors, with a duct bringing in air from the outside.

Can air source heat pumps be wall mounted?

Yes, heat pumps can be wall mounted, but it is much simpler to have them on the ground. If you do get a heat pump unit wall mounted using brackets, it’s important that there’s enough space around the unit to have good airflow. A wall-mounted heat pump if often harder to reach as well, which is likely to make servicing more complex – and potentially more expensive.

Where is the best place to put an air source heat pump?

Most people have their heat pump unit installed at the back or on the side of the home. Installing a heat pump on the ground just outside the property means it uses less space, minimises the amount of pipework and avoids unnecessary heat loss.

Do you need new radiators to install an air source heat pump?

Not necessarily, but many homes do. Heat pumps create steady heat at a lower temperature than boilers. This makes them more energy efficient, but you might need radiators with a larger surface area to keep your home at a comfortable temperature. During your survey, we’ll recommend the right heating system to get the maximum comfort and efficiency from your heat pump – and your quote will include any extra work you need to your pipework and radiators.

Is planning permission needed to install an air source heat pump?

No. Unless you live in a listed building or in a conservation area, you won’t need planning permission for a heat pump. They’re classified as a permitted development.