Heat pumps vs gas boilers: what’s the difference?

We're moving into a world in which going green is becoming ever more important. The good news is it’s also becoming ever more possible. And nowhere is this more the case than when it comes to heating your home.

One of the biggest steps forward for domestic heating systems has been the rise of the air source heat pump.

Air source heat pumps are super energy-efficient and sustainable. And thanks to these planet-saving credentials, along with pocket-friendly government incentives to help with installation, heat pumps have become one of the leading alternatives to gas heating.

But here’s the thing: when exactly is it right to replace your gas boiler with a heat pump? Is it the right choice for your property? What are costs associated with installation? There’s a lot to consider.

In this guide, we'll aim to answer these questions—giving you all the information you need to decide on the right choice for you. Let's get started.

Air source heat pump vs gas boilers: overview

First up, let's take a quick look at what gas boilers can offer versus air source heat pumps.

Gas boilers

Gas boilers heat water by burning natural gas. They're used in over 20 million homes in the UK , and they're integral to central heating and hot water systems.

You'll probably be most familiar with the combi boiler, a system that combines water heating and central heating in one unit. Combi boilers provide hot water on demand without a storage tank, making them great for space-saving.

In terms of installation costs: depending on the type you're getting (and how complex the install is) you could be looking at around £4,000 for a new gas boiler.

Nowadays, gas boilers are very efficient, and certainly a far better solution than an old oil boiler. In fact, modern condensing gas boilers are at least 90% efficient. However, obviously gas boilers still rely on natural gas which contributes to CO₂ emissions.

Air source heat pumps

So, what about air source heat pumps? How do they work, and how do they compare with gas boilers in terms of costs, efficiency and eco-friendliness?

In terms of how they work, heat pumps run on electricity, and they work by extracting heat from outside air, using a refrigeration cycle. A fan in the heat pump pulls air in, then a refrigerant absorbs heat as it evaporates. The warm refrigerant vapor is compressed to raise its temperature and then heat is transferred to a water or air system.

Because heat pumps can extract heat so well, they are extremely efficient. In fact, they have typical efficiency rates of 300% to 400%!

That said, they do still require electricity to run. So while your heating will be super eco-friendly, there are still running costs involved. (That said, many electricity companies, including British Gas, are beginning to offer special lower tariffs for electricity used for air source heat pumps).

Want to see how gas boilers and heat pumps stack up side-by-side? Our handy heat pump vs boiler table below has all the key numbers in one place.

Heat pump vs gas boiler cost comparison

So, is a heat pump cheaper than gas? Well, there are two areas to consider here: installation and running costs. Let's look at each:

Installation

The fact is, there's going to be quite a big cost to fitting a new heating system, whether you choose a gas boiler or an air source heat pump.

For heat pump installation, it's worth remembering that the UK government's Boiler Upgrade Scheme can help with costs. We'll look at that in more detail further on, but with up to £7,500 in grants available, that heat pump installation might not end up being that much more expensive than a gas boiler.

You can find out more about heat pump installation in our dedicated guide here.

Running costs

So, what about operational costs for an air source heat pump vs gas boiler? Heat pumps run on electricity, which is currently around four times as expensive as gas. So, by that reckoning, the running costs for a gas boiler will be much cheaper.

But that's not the whole story. Heat pumps run more efficiently than gas boilers, meaning the cost difference isn't that substantial.

Experts agree that on average, a gas boiler typically costs £694 per year to run, and an air source heat pump costs £1,097 per year.

What’s more, that’s also before the special lower tariffs for electricity used for air source heat pumps that many electricity companies are offering, including British Gas.

It's also worth remembering that heat pump costs can vary dependent on property type. To get the most efficiency from a heat pump system, your home needs to be well insulated with larger radiators. If these things aren't in place, they'll need to be factored into your budget. Luckily, our friends at British Gas also offer a free home survey and tailored quote to help you get to grips with potential costs.

Want to learn more about heat pump costs? Look at our in-depth article here.

How do heat pumps perform in comparison to boilers?

Here in the UK, our climate is probably best described as changeable. So, we need heating systems that can react to a cold snap and keep us warm during long winters.

It's easy to imagine that, because of their eco-credentials, heat pumps might not be able to keep your home warm when the temperature dips. But that's not the case. In fact, Europe's coldest countries (Norway, Finland, and Sweden) have the most heat pumps per million households.

Now, it's worth remembering that gas boilers operate by heating water to high temperatures quickly, which means they can rapidly warm a cold home. But in a well-insulated home, the slow and steady—but consistent—heat release of a heat pump system will keep your home cosy all year round.

What are the environmental impacts of heat pumps vs gas boilers?

It's not surprising to learn that gas boilers generally have a more negative environmental impact than heat pumps. That's because gas boilers burn natural gas, releasing significant CO₂ emissions directly into the atmosphere. A typical UK home with a gas boiler emits around 2.2 tons of CO₂ annually.

In contrast, heat pumps run on electricity, so produce no on-site emissions. Of course, their carbon footprint depends on the electricity source—but thanks to the efficient nature of heat pumps, that footprint won't be excessive. And if the heat pump is powered by renewable energy – through your energy provider or solar panels on your property – it can operate nearly carbon-free.

What government grants and incentives exist for heat pumps and boilers?

Replacing gas boilers with heat pumps is vital for the UK government’s net-zero targets. After all, heating accounts for around 20% of UK emissions.

So while the up-front installation cost fitting an air source heat pump can be a barrier, luckily there are grants and incentives available to people in the UK to help bring down that cost. Let's look at some of the most popular options:

Boiler Upgrade Scheme (BUS)

The UK government’s Boiler Upgrade Scheme provides homeowners in England and Wales with a £7,500 grant towards the cost of a heat pump.

Home Energy Scotland Grant

If you're a homeowner in Scotland, you can access the Home Energy Scotland Grant. Like the BUS, it contributes £7,500 towards the cost of a heat pump, plus a potential £1,500 extra if you live in a rural area.

Energy Company Obligation Scheme (ECO4)

The ECO4 initiative from the UK government requires large energy companies to support low-income households. If you qualify, the government could cover the entire cost of making energy-efficient upgrades to your home.

There are specific criteria that need to be met in order to access these grants and incentives. If you want to get the full lowdown, read our guide to heat pump grants here.

What about grants and incentives for gas boilers? The ECO4 scheme could help with the cost for a new boiler if you're from a low-income household. Likewise, the Affordable Warmth Scheme in Northern Ireland offers similar support for those potentially at risk of fuel poverty.

What is the typical longevity of heat pumps vs gas boilers?

Heat pumps typically have a longer lifespan than gas boilers. Thanks to their simpler design and relatively few components, heat pumps can last about twice as long—they'll generally last between 20-25 years, while gas boilers usually last 10-15 years.

It's important to remember that both heat pumps and gas boilers will have a longer lifespan if they're serviced annually by a professional.

Frequently asked questions

Should I replace my gas boiler with a heat pump?

We want to say yes, as air source heat pumps are a brilliantly sustainable and efficient way to heat your home! If you’re eligible for a grant, your old gas boiler is at the end of its life, and you’re in a well-insulated home, an air source heat pump could definitely be the answer.

That said, an air source heat pump is not a 100% no brainer for everyone quite yet: while it will reduce carbon emissions and energy bills in well-insulated homes, you'll need to consider the type of home you live in and be able to handle the slightly higher up-front costs. You'll also need outdoor space for the unit and space for a water tank.

What are some other heating alternatives to gas boilers?

Electric boilers are compact and common, but costly to run without renewable power. Solar thermal systems efficiently heat water, but they rely on sunlight, and you'll need backup. Biomass boilers use renewable fuel but need storage and maintenance. Heat pumps and gas boilers remain the most cost-effective options.

Is a heat pump cheaper to run than a gas boiler?

Heat pumps are the cheaper long-term option due to their high efficiency, longer life and lower maintenance. Running costs do depend on energy prices, and electricity is more expensive than gas. But while electricity costs more than gas, heat pumps will use less energy over time. So, for most homes, the heat pump option will work out cheaper in the long run.

Can any home accommodate a heat pump?

Not every home will be able to take a heat pump. You'll need some outdoor space to locate the unit and enough indoor space to fit a water tank. On top of this, your home will require good insulation and larger radiators to make sure your heat pump can work efficiently.

Are you thinking about a heat pump for your home? Great! Get in touch with us for a quote, and get your home set for a greener future with Hive.