Heat Pumps vs Traditional Boilers: Which is Right for You?

If you're a UK homeowner or tenant considering an upgrade to your heating system, you may be wondering whether to stick with a traditional gas boiler or switch to a modern air source heat pump. It's an important decision – around 85% of homes in England, Scotland, and Wales currently use gas boilers for heating. However, the push toward net-zero emissions by 2050 means low-carbon alternatives like heat pumps are gaining attention.

In fact, the UK government has signaled plans to ban new gas boiler installations by 2035 as part of its climate strategy. In this article, we'll compare air source heat pumps vs. traditional gas boilers in terms of how they work, efficiency, costs, and environmental impact. We'll also cover UK-specific factors – including energy prices and government incentive schemes (like ECO4 and the Great British Insulation Scheme) – to help you decide which heating solution is right for your home.

How Do Heat Pumps and Boilers Work?

Air Source Heat Pumps (ASHPs)

Air Source Heat Pumps gather heat from the outside air and use a refrigerant cycle (much like a refrigerator in reverse) to boost that heat to a higher temperature. Even in chilly UK winters, an ASHP can extract ambient heat from the air and transfer it into your home's heating system. The heat pump runs on electricity and typically distributes warmth via radiators or underfloor heating. Because it moves heat rather than generates it by burning fuel, a heat pump can produce several kilowatts of heat for each kW of electricity it uses – making it highly efficient.

Traditional Gas Boilers

Traditional Gas Boilers, on the other hand, burn natural gas to directly generate heat. A boiler heats water that then circulates through radiators or underfloor pipes to warm the house. Modern condensing gas boilers are quite efficient at extracting heat from combustion (often 90%+ efficient), but they still rely on fossil fuels and emit carbon dioxide via the flue. Gas boilers are usually compact units installed indoors (like in a kitchen cupboard or utility room), and many UK homes already have the necessary gas connections and radiator systems in place.

Efficiency and Performance

When it comes to energy efficiency, heat pumps have a clear advantage over gas boilers. A modern A-rated gas boiler typically operates at about 88–94% efficiency (meaning a small portion of heat is lost in exhaust). Older boilers fare worse – a dated boiler with a D–G efficiency rating might only be ~70% efficient.

By comparison, an air source heat pump can achieve 300% (or higher) efficiency, because it outputs 3–4 kWh of heat for every 1 kWh of electricity it consumes. In practical terms, this means a well-installed heat pump delivers more heat per unit of energy, significantly outperforming even the best gas boiler on efficiency.

That said, getting the most out of a heat pump requires a well-insulated home. Heat pumps deliver water at a lower temperature than boilers, so your house should retain heat well (through good loft and wall insulation) to maintain comfort. If your home is poorly insulated or has undersized radiators, you may need to address those issues (or use larger radiators) when switching to a heat pump.

Boilers are a bit more forgiving on this front, since they blast high-temperature water that can quickly heat up even a draughty room – but you'll end up burning a lot of gas to keep it warm. In summary, for efficiency and steady performance, heat pumps win as long as your home is adequately insulated, whereas boilers are less efficient but can spike high heat output when needed.

Heating Costs: Upfront and Running Expenses

One of the biggest considerations is cost. Let's break it down into installation costs and running costs for boilers vs heat pumps:

Upfront Installation Costs

If you're on a tight budget initially, a gas boiler has a clear edge. A typical new gas boiler installation in the UK costs roughly £1,000–£4,000 including the unit and labor. In contrast, installing an air source heat pump system is a much larger investment – usually in the range of £7,000–£13,000 for an ASHP (and even more for ground source heat pumps). In real-world terms, many homeowners pay around £10,000 for a heat pump install versus ~£3,000 for a boiler.

The heat pump often also involves additional work like installing a hot water cylinder (if you currently have a combi boiler) or upgrading insulation. The good news is there are generous government grants available (which we'll cover below) that can knock as much as £5,000–£7,500 off the heat pump cost for eligible homes, helping bridge the upfront cost gap.

Running Costs

Historically, gas has been cheaper per kWh than electricity in the UK, which made boilers seem cheaper to run. However, the equation is changing. Heat pumps are so efficient that their monthly energy bills can rival or even beat gas boiler bills, especially with recent energy price shifts.

An independent analysis by the Regulatory Assistance Project found that an average UK home might spend about £1,302 per year on heating with a gas boiler, versus roughly £1,156 per year with a well-designed heat pump – a savings of about £146 annually. In other words, while electricity is more expensive than gas per unit, the heat pump's 300% efficiency balances things out in its favor.

If you can power the heat pump with home solar panels or take advantage of off-peak electricity tariffs, the running cost can be even lower. For a new A-rated gas boiler vs a heat pump, today's running costs are relatively similar (with the heat pump sometimes slightly cheaper). The biggest savings come if you're replacing an old inefficient boiler – going from a clunky D-rated boiler to a heat pump could save you a few hundred pounds per year in fuel bills.

Maintenance and Lifespan

Both boilers and heat pumps require annual servicing by a qualified technician to keep them running safely and efficiently. Maintenance costs are comparable for the two (think of an annual service on a heat pump like a boiler service). However, the lifespan of the systems differs.

A well-maintained gas boiler typically lasts about 10–15 years before needing replacement. An air source heat pump can often heat your home for 20+ years (potentially even 25–30 years) if looked after properly. Over the long run, that means a heat pump might serve you roughly twice as long as a boiler, offsetting some of the higher upfront cost.

Additionally, heat pumps have fewer moving parts and don't require fuel deliveries or combustion, so some homeowners find them to be lower-hassle in day-to-day operation (and there's no risk of carbon monoxide leaks).

Environmental Impact

For many people, the environmental angle is a big motivator to consider a heat pump. Here's how the two options stack up:

Carbon Emissions

Every time a gas boiler fires up, it directly burns natural gas and releases carbon dioxide (CO₂) into the atmosphere. An 85% efficient gas boiler produces roughly 0.215 kg of CO₂ per kilowatt-hour of heat delivered. This adds up significantly across a year of heating.

In contrast, an electric heat pump has no on-site emissions – it doesn't burn any fuel at home. The carbon footprint of running a heat pump depends on how the electricity is generated. With today's UK grid mix, heat pumps still come out far ahead: the effective emissions of a heat pump are more than five times lower per kWh of heat than those of a gas boiler.

To put it simply, a heat pump dramatically cuts the carbon footprint of home heating. And as the grid gets greener (more wind, solar, etc.), heat pump emissions will drop further. If you power your heat pump with 100% renewable electricity or your own solar panels, the heating can be virtually zero-carbon.

Environmental Sustainability

Heat pumps harness a renewable heat source – ambient air – which is inexhaustible and naturally replenished by the sun. Gas boilers rely on fossil fuel extraction and pipeline delivery of gas, which has broader environmental impacts (from drilling to the risk of leaks). By switching to a heat pump, you're contributing to the reduction of fossil fuel use and supporting the UK's goals to reduce greenhouse gas emissions. The UK's Net Zero Strategy by 2050 heavily leans on widespread adoption of heat pumps and other clean heating technologies.

In summary, when it comes to environmental impact, heat pumps are the clear winner over traditional boilers.

Practical Considerations (Space, Noise & Suitability)

Aside from cost and efficiency, think about the practical implications for your home:

Space Requirements

An air source heat pump unit is usually a box about the size of an AC unit that sits outside your home (on the ground or wall-mounted). You'll need a bit of outdoor space for it, plus possibly space indoors for a hot water cylinder (unless you opt for a hybrid or high-temperature system that works with a combi-like setup).

Traditional boilers are typically wall-hung inside a kitchen, bathroom, or cupboard. Combi boilers don't need a separate hot water tank, which saves space, whereas heat pump systems generally do use a hot water cylinder to store heated water. On the flip side, heat pumps free up indoor space – there's no furnace-like unit inside your main living area (just a modest unit outside).

Noise Levels

Modern boilers and heat pumps are both designed to be relatively quiet, but there is some noise to consider. A gas boiler makes a whooshing sound when it ignites and a low hum during operation (often around 45 dB for a newer model). It's inside the house, but usually enclosed in a cupboard, so you may only hear it when nearby.

An air source heat pump has a fan and compressor that generate sound (typically 50–60 dB range, similar to a refrigerator or a quiet conversation). The heat pump's noise is outside your home, so it may be less noticeable indoors – but you'll hear it if you're near the unit or if it's placed by a bedroom window. In practice, many users report hearing more noise from an indoor boiler than from a properly installed outdoor heat pump. Still, it's wise to discuss placement with your installer to minimize any disturbance (for you or neighbors).

Suitability and Heating Comfort

Heat pumps deliver a gentler, steadier heat – they often run for longer cycles at lower temperatures compared to the quick, high-flame bursts of a boiler. Some homeowners love the consistent warmth; others worry it won't feel as toasty as fast. With the correct design (sized appropriately for your home and radiators or underfloor heating), a heat pump can absolutely heat a UK home to comfort even in winter. It might take slightly longer to raise the temperature from cold, but once running, it keeps things very even.

If your home is large or particularly draughty, you might need a higher capacity heat pump or additional insulation upgrades to get the best results. Always have a heat pump installer assess your property's heat loss to ensure the system is designed right. Gas boilers, by contrast, can blast heat quickly but also tend to create more swings (on-off cycling).

In terms of hot water, both systems can provide hot taps and showers. A combi boiler gives unlimited hot water on demand (but no backup if it fails). A heat pump usually works with a hot water cylinder that stores hot water – meaning you'll have a reserve of hot water, but the cylinder size dictates how much is readily available at once. Many heat pump setups include an electric immersion heater for boosting water temperature or providing backup for very cold weather.

UK Government Incentives and Grants (ECO4, GBIS, BUS)

Upfront cost is a major barrier for heat pumps, but the UK government has stepped in with incentives to encourage energy-efficient heating. Here are key schemes and how they can help you:

Boiler Upgrade Scheme (BUS)

This is the flagship heat pump grant for England and Wales. Under the BUS, homeowners can get up to £7,500 off the cost of installing an air source or ground source heat pump. The grant is typically £5,000 for an air source heat pump (and £6,000 for ground source), but as of 2023 the government increased it to £7,500 for heat pumps to drive uptake. This voucher is applied by your installer, effectively slashing the price of a heat pump installation (note: gas boilers are not eligible for this grant).

To qualify, you generally need to own your home (not a new build) and have an existing fossil fuel heating system to replace, plus a valid EPC (Energy Performance Certificate) with no outstanding insulation recommendations. The BUS runs until 2028 or until funds are used up.

Energy Company Obligation (ECO4) Scheme

ECO4 is a government-backed program (April 2022 – March 2026) aimed at helping low-income and fuel-poor households improve home energy efficiency. It takes a "whole house" approach – meaning if you qualify (often based on receiving certain benefits or having a very low-efficiency home), an energy provider can fund a package of improvements. This could include insulation, heating controls, and even installing a heat pump with insulation upgrades at little to no cost for the homeowner.

ECO4 is focused on cutting carbon emissions and reducing bills for vulnerable households, so eligibility is strict. But for those who do qualify, it's an excellent way to replace an old boiler with a new efficient heat pump fully or partially funded by the scheme.

Great British Insulation Scheme (GBIS)

Launched in 2023 (formerly called ECO+), GBIS complements ECO4 by focusing mostly on single insulation measures for homes that are not very efficient. It targets a broader range of households – not just low-income – including homes with EPC ratings of D to G and within certain council tax bands.

While GBIS is primarily about subsidizing insulation (loft insulation, cavity wall insulation, etc.), it's highly relevant if you're considering a heat pump. A well-insulated home is crucial for heat pump performance, and through GBIS you might get insulation upgrades either free or heavily discounted. In short, GBIS can help cut your heating demand (and bills), making a heat pump more viable. The scheme runs until 2026 and is delivered via energy suppliers who are obligated to help customers save energy.

Other UK Incentives

There are additional programs depending on where you live. In Scotland, for example, Home Energy Scotland offers interest-free loans (with some cashback grants) for heat pumps and other green improvements. Wales has the Nest scheme, providing free advice and in some cases free installations of heat pumps or insulation for eligible households.

Across the UK, VAT on heat pump installations is now 0% (zero) until 2027, which directly knocks 5% off the cost automatically. This VAT relief can save around £750 on a £15,000 heat pump install, for instance.

Bottom line: If you opt for a heat pump, make sure to take advantage of these grants and schemes. Most UK homeowners will qualify for at least one form of support to reduce the cost. Checking your eligibility and applying (or letting your installer apply on your behalf) can make the price of a heat pump installation much more palatable – sometimes bringing it close to the net cost of installing a boiler. Traditional gas boilers, by contrast, have virtually no government grants available for standard installations, since policy is firmly geared toward cleaner energy systems.

Conclusion: Which Heating System is Right for You?

Choosing between a heat pump and a traditional boiler ultimately depends on your home's characteristics, your budget, and your eco priorities. To summarize:

If you value maximum efficiency and a lower carbon footprint

An air source heat pump is the winner. It will dramatically cut your home's CO₂ emissions and can deliver 3-4 units of heat per unit of electricity. Over the long term, it could save on running costs – especially if gas prices rise or if you're replacing an old inefficient boiler. With a heat pump, it's important that your home is well-insulated and that you're prepared for a higher upfront cost (though grants can offset this). You'll also enjoy a longer system lifespan and eliminate the need for gas supply or combustion in your home.

If you need a lower upfront cost solution

Or your property isn't heat-pump-ready, a modern gas boiler remains a reliable choice (for now). It's cheaper to install, and a new A-rated boiler still offers decent efficiency (90%+). In very poorly insulated or large old houses, a boiler might heat the space more quickly for short bursts of time. However, keep in mind the running cost advantage of boilers has narrowed – and may disappear as electricity gets greener and possibly cheaper relative to gas. Also consider future regulations: installing a new gas boiler in 2025 means you might need to replace or retrofit it by the mid-2030s if policies change.

Many UK homeowners are actually choosing a hybrid approach – for example, keep an existing boiler as backup and add a heat pump to handle the bulk of heating, leveraging the strengths of both. But for most, it's an either-or decision.

Next Steps – Get Personalized Advice

Still unsure which is right for you? The best next step is to get a professional assessment of your home's heating needs. You may be eligible for generous UK government grants (such as ECO4, GBIS, or the Boiler Upgrade Scheme) that make switching to a heat pump much more affordable.

Renew Energies offers free home assessments to help you determine your eligibility and find the ideal energy-efficient heating solution for your property. Our experts will evaluate your home, explain your options in plain language, and even handle the grant application process for you.

Contact Renew Energies today to check your eligibility for funding and get a free, no-obligation assessment – take the first step toward a greener, more cost-effective heating system for your UK home!