Air Source Heat Pump vs Gas Boiler: Which One’s Best?

Air Source Heat Pump vs Gas Boiler?

In Summary:

Our detailed comparison of air source heat pumps vs gas boilers is an approximate 10-minute read. If you’d prefer, bookmark this for later and read this short summary instead…

Running costs for new A-rated gas boilers are comparable to an air source heat pump (ASHP). The big savings (£100s per year) come for those switching out an old boiler that’s D-G rated. 

New A-rated gas boilers work at around 88-94% efficiency, whereas old ones could be as low as 70%. An air source heat pump? Generally, 300% efficiency or higher. 

The upfront installation cost of a heat pump could be in the region of £10,000, compared to that of roughly £3,000 for a gas boiler. However, thanks to government grants, you could be eligible for up to a £7,500 discount on your ASHP (not applicable to gas boiler installations).

Noise levels for new gas boilers (44-48dB for the Ideal Logic Plus) are lower than an ASHP (54dB for the Vaillant aroTHERM). However, gas boilers are installed inside, whereas pumps are installed outside. Put simply, you’ll hear more noise from your gas boiler than a heat pump. 

A huge benefit of heat pumps, is they don’t take up space indoors (gas boilers do). And, maintenance is relatively simple. With less moving parts, that’s less to break and less to replace. 

A typical gas boiler will last around 10-years, with lots of replacement parts along the way, compared to a relatively trouble free 25-year lifespan of an air source heat pump. 

Ready to see what government grants you’re eligible for, and the most suitable heat pump for your property? Use our 2-minute clickable heat pump page here. 

Comparison: Air Source Heat Pump vs Gas Boiler

In our air source heat pump vs gas boiler comparison, we’ll be seeing how both units stack up in terms of: 

• Energy consumption and overall running costs
• Installation costs
• Eligibility for government grants
• Efficiency ratings
• Noise levels
• Space needed 
• Maintenance schedule, lifespan and repair costs

Running Costs

On average, heat pump running costs sit in the region of £67-£208 per month. 

Why the big variation in price? 

Typical residential heat pumps are offered from 5kW up to 17kW (much larger for commercial units) power outputs. The bigger your property is, the more your demand for heat and hot water is and the bigger kW output of your unit, the higher your monthly bills are likely to be. 

That said, air source heat pumps are generally slightly better in terms of running costs than a new, efficient and A-rated gas boiler. 

The big savings on running costs really come if you have an old and inefficient boiler, highlighted by this chart courtesy of the Energy Saving Trust.

Whilst the running costs of a newer A-rated gas boiler will be similar (or slightly more) than an air source heat pump, that’s because they run at between 88%-94% efficiency. As you can see above, older boilers (D-G rated) will work at a much lower efficiency, sometimes as low as 70%. 

If you have an old gas boiler that is D-G rated, it’s likely the running costs of an air source heat pump will be £200-£400 cheaper per annum. We’ve written a detailed guide to air source heat pump running costs that explain this further.

Another consideration here, is running costs of an air source heat pump can be reduced by coupling your pump with solar panels. We fit solar panels to work alongside heat pumps, which doesn’t just mean your heating bills could go to zero, your total electricity bill could go to zero too!

Boilers running on gas won’t see the same running cost benefit. Installing solar panels is only going to reduce their running costs by a few pounds per year (the amount of electricity the boiler uses on standby and when operational).

You can jump over to our air source heat pump clickable quote form here, and get a fixed price on-screen. There’s an option to “Add a solar panel system” once you’ve picked your ASHP.

Installation Costs

The next heat pump vs gas boiler comparison we’ll do is installation costs.

As you can see on our new boiler installation costs page here, you should expect to pay around £3,000 for a new gas boiler. This would get you a quality A-rated boiler such as the Ideal Logic Plus, which comes with a manufacturer’s warranty of up to 10-years. 

Installation costs for air source heat pumps are generally a lot higher than fitting a new gas boiler. 

Ballpark figures for a 7kW installation sit in the region of £10,000, as you can see here with the Vaillant aroTHERM Plus. This fixed price was generated using our clickable heat pump form here.

Whilst the overall installation cost for the ASHP is over £10,000, a lot more than the equivalent gas boiler, it’s eligible for up to £7,500 in government grants. 

Essentially, this means that the ASHP is similar in installation cost to a gas boiler installation, when accounting for eligible government grant discounts.

Government Grants 

There are very few government grants for new heating systems that use fossil fuels. This means if you’re looking for a gas boiler grant, you’re out of luck. 

As the UK moves closer to its net-zero target, the grants on offer for non-fossil fuel based heating systems is increasing. That means there are plenty of grants available for air source heat pumps, ground source heat pumps and even biomass boilers. 

And this is where you’ll see a big win by installing an air source heat pump vs a gas boiler. An ASHP will qualify (subject to eligibility) for a government grant of up to £7,500, and a gas boiler won’t. And as we’ve mentioned above, that equates to gas boilers and ASHP systems being similar in price to install. 

One of the most popular government grants for heat pumps at the moment, is the Boiler Upgrade Scheme. 

You can read about it on the government website here. Or, simply use our clickable heat pump tool. This will give you fixed prices on-screen for the best heat pumps, with any discounts for government grants you’re eligible for incorporated into the price. 

Efficiency

When it comes to efficiency, air source heat pumps beat gas boilers hands down. 

Whilst a typical heat pump will work at around 300% efficiency or higher, new gas boilers work at just 94% efficiency. Have an older gas boiler? The efficiency here could be as low as 70%!

In the example above, the air source heat pump would use 1kWh of electricity to produce 3kWh of heat. By comparison, the gas boiler would produce somewhere between 0.7kWh-0.94kWh of heat for every 1kWh unit of gas that it uses. 

If you’re looking for more details on exactly how efficient heat pumps are compared to gas boilers, visit our heat pump efficiency page here. We cover the likes of CoP, SCOP and SPF energy ratings. 

Or, if you’re ready to get a quote on a heat pump, use our heat pump installation tool here. 

Noise

Noise is a common concern for people replacing their gas boiler with a heat pump. 

Heat pumps are noisy, that’s a fact. A reasonably quiet unit will operate at around 54dB (Vaillant aroTHERM Plus). A gas boiler that could power the same property’s heating and hot water would work at around 44-48dB (Ideal Logic Plus gas combi boiler). 

So, you should avoid an air source heat pump and fit a new gas boiler instead? Not exactly…

One of the main things people forget is that gas boilers are usually installed inside, whereas air source heat pumps are typically fitted outside. 

As long as you don’t fit your ASHP below a window you leave open regularly in summer, it’s unlikely you’ll hear anything from your pump, and your neighbours won’t either. In comparison, a gas boiler fitted in a kitchen or airing cupboard, you will hear. 

You can read more about the noise of heat pumps vs gas boilers in our air source heat pump noise guide here. 

Looking for a quiet air source heat pump? You can get a quote on a heat pump here. 

Property dependent, we’ll suggest a suitable unit such as the: 

• Samsung EHS
• Grant Aerona³ R32
• Ideal Logic Air
• Vaillant aroTHERM Plus

Space Required

As we mentioned above, gas boilers are fitted inside, whereas air source heat pumps are usually fitted outside. 

Looking for a gas boiler replacement? You’ll need to use up crucial space indoors such as an airing cupboard or kitchen cupboard. 

Switching your heating system over to an air source heat pump? You’ll be able to make use of extra space you have outside rather than taking up space indoors. 

Maintenance & Repair Costs

Both gas boilers and air source heat pumps need regular maintenance. Typically, regardless of the unit your property uses, you’ll want an annual service. 

For boilers, you’ll need a Gas Safe boiler engineer to inspect dozens of expensive components such as the fan, heat exchanger, fan, air pressure switch and gas valve. Whilst a basic service may cost as little as £100, if any of these parts have failed, you could be looking at a hefty bill of £100s in addition to your boiler service cost.

Heat pumps are generally much easier to maintain and to work on. They have fewer mechanical parts, which means there is less to go wrong. Maintenance costs are similar, with an annual service including the likes of visual inspection, cleaning the fan blades and cleaning / replacing the filter to ensure maximum airflow. 

In summary, service costs for gas boilers and air source heat pumps are similar. 

The big cost difference comes when repairs are needed. Typically, modern boilers will last around 10-years, whereas reliable heat pumps can last up to 25-years, with very little in terms of repair costs during their lifespan. This makes air source heat pumps much more cost effective long-term in comparison to gas boilers.

Ready to get your air source heat pump fitted? Use our heat pump tool here, and we’ll suggest the most cost effective pump for your property. 

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