Pros and cons of Air Source Heat Pumps.

Article by: Sam Dewey

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Introduction

The future is here, gas prices are soaring at an all-time high, so many of us are turning our attention to how we heat our homes for a much reasonable price. Did you know that around 85% of us in Britain have boilers that burn natural gas? This makes heating one of the largest carbon contributors to carbon emissions in the home.

To reach our national Net Zero carbon emissions target by 2050 almost all of our homes need to switch over to low carbon heating. At the moment just 5% of us in the UK have low carbon heating, so at this rate, it’ll take us a staggering 700 years to reach our Net Zero goal! But by 2025, no new homes should be connected to the gas grid, meaning the future of Air Source heat pumps looks very promising.

With the increase in heat pump deployment, the UK government grants make this renewable energy source even cheaper to run and reduces the burden of air source heat pump installation costs.

What is an Air Source Heat Pump and how does it work?

An air source heat pump (ASHP) is an alternative way to heat your home or commercial premise. It will enable you to generate your own renewable heat and help save money on your energy bills. Simply put, an air source heat pump takes heat from the air and transfers it to a higher temperature using a compressor. It then moves this heat to the central heating system in your home. Heat pumps work similarly to a refrigerator: they absorb heat and transfer it to another medium.

Certain air source heat pumps can also work as a cooling system in the summer months. Most commonly they are placed outside of a building where there is adequate space for the installation.

There are two main types of air source heat pumps:

Air to air heat pumps, which absorb heat from the outside air and then transfer it directly into your premise to heat a room.
Air to water heat pumps, which absorb heat from the outside air and then transfer it via your central heating system to provide hot water heating, radiator, or underfloor heating in an indoor space (or all three).

But, before making the switch there are various things to consider. Therefore, we have put together a list of the advantages and disadvantages that air source heat pumps have to offer, so you can have an easier time deciding if this method of heating (and cooling) is a viable option for you.

10 Advantages of Air Source Heat Pumps.

There are numerous benefits to using air source heat pumps. With this system, you can save money on your energy bills and reduce your carbon footprint compared to a gas or electric heating system.

One of the key advantages of air source heat pumps is their versatility and affordability. An ASHP can work for either heating or cooling purposes and can be used for space heating or water heating too. Let’s explore in more detail our list of positives for air source heat pumps.

Low Carbon Footprint:

Air source heat pumps are a form of low carbon heating, as they use the outside air to heat or cool your property. If you are switching from a coal or gas-based heating system, you can significantly reduce your carbon emissions. Installing a heat pump could cut your carbon emissions by more than 23 tonnes of CO₂ over 10 years. That’s the same as 30 return plane flights between Heathrow and Madrid.. And with the global push to try and reduce our collective carbon footprint, ASHPs are a great starting point!

Eligible for the Boiler Upgrade Scheme:

By swapping over to a domestic heat pump, you could receive an initial £5000 from the UK Government through the Boiler Upgrade Scheme. By making use of this green energy scheme, you can save even more on your energy bills.

If you would like to discover more about this, read our article discussing everything you need to know.

Suitable for domestic and commercial use:

Air source heat pumps are the ideal solution for both domestic and office premises, business parks and commercial enterprises. Heating commercial premises with a heat pump can significantly reduce heating costs and increase your organisation’s green credentials.

The low-level constant heat will also create a better working environment for employees. You will also be shielded long term from the volatility in fossil fuel prices, which, when rising, can generate a considerable extra cost to a business. The next energy increase is likely to hit around April 2023 with prices reaching an unpredicted level. There really hasn’t been a better time to switch over to green energy.

High Seasonal Coefficient of Performance (SCOP):

Traditional boilers have a 50 to 75% efficiency rate, meaning around a third of the supplied energy to the boiler is wasted. Even biomass boilers and modern oil, LPG and gas boilers have an efficiency at around the 90% mark.

Air source heat pumps topple this by a country mile, reaching up to an average 350%, with a coefficiency of performance (COP) measuring 3.5. In ideal conditions however, an air source heat pump can be 400% efficient, which is truly mind blowing. The higher the COP, the better.

Now, it’s not always going to be the ideal conditions for a heat pump to work in and outdoor air temperature can significantly affect the efficiency of an ASHP.

When considering an air source heat pump’s COP vs outside temperature, you will find that despite some slight fluctuations, they can run efficiently all year-round. To be able to compare heat pumps based on how much they are affected by these efficiency changes, the seasonal COP is used.

Low Maintenance:

Servicing and maintenance should be done by a technician once every 2 years as a minimum. As such air source heat pumps are quite low maintenance, but there are a few things that you can do to ensure optimal performance of your heat pump, from cleaning filters, to checking for system leaks, checking refrigerant levels, clearing leaves and dust from your heat pump, and so on. Any more technical tasks should only be done by a certified installer.

Read our article on the tips to maintain your air source heat pump or please get in touch if you require specialist support!

Save Money on Energy Bills:

By switching to air source heat pumps, you can reduce your energy bills as you’ll be using the outside air for your heating and cooling needs. Your savings will be more significant if you are going from a gas or coal-based system. Although the upfront cost is fairly high, you will be eligible to receive a significant portion of your investment from the Boiler Upgrade Scheme as previously mentioned.

The running costs of heat pumps depends on a few factors, from the efficiency to the amount of heat needed, and the temperature of the heat source. While they do use electricity, ASHPs can be combined with renewable energy sources such as solar for clean electricity.

Can Be Used for Heating and Cooling:

Air source heat pumps can be used for both heating and cooling purposes. Depending on the model, they can provide cooling in the summer and heating in the winter. All you need to check is that the COP of your air source heat pump should be above 0.7 for cooling. All year-round climate control, what is better than that!

Can Be Used for Space Heating and Hot Water:

Depending on the air source heat pump, you can also use it to heat your water. This depends on the temperature of the water in the heating system (also known as ‘flow temperature’). To be able to heat water, the flow temperature needs to be approximately 55°C. If your system is only designed for space heating, the flow temperature will be 35°.

If you are looking for both space heating and water heating, then opting for an ASHP that has a flow temperature of 55°C is needed. This again is a great method of energy saving and reducing your carbon footprint if you link it with a renewable energy source.

Easy Installation Process:

Installing an air source heat pump can take as little as 1 single day and is quite simple as there’s no need for extensive groundworks. A domestic air source heat pump typically doesn’t require planning permission, but it is always advised to check with the local authority before you start your process. It’s an ideal option for both retrofits and new builds. If you are combining air source heat pump installation with other building work, you can also bring down the cost of installation.

Check out our guide on the standard air source installation process within the UK.

Long Lifespan:

Air source heat pumps have a long lifespan, and with proper maintenance, they can be operational for up to 25 years. What’s more, is that most air source heat pumps have multiple year warranties. With several technological developments modern heat pumps are able to work efficiently for close to 25 years before they need replacing. Quite astonishing when comparing to a gas fired boiler which will need replacing at about the 10-year mark.

7 Disadvantages of Air Source Heat Pumps:

So, we’ve had a look at what we believe to be the best 10 advantages of air source heat pumps but it’s also crucial to be aware of the potential shortfalls. Afterall, you need to be 100% sure this is the correct system for you!

Let’s check out what we believe are the main disadvantages of air source heat pumps..

Both systems have similar running costs, for now..

While air source heat pump installations may have a higher initial cost, it’s essential that you weigh up the running costs of whichever heating method you choose. After all, you need to know what you’ll be paying for your energy in the long term.

Gas can be, on average, cheaper than electricity in terms of energy costs from your provider. However, as air source heat pumps can be much more efficient than gas boilers (which we discuss more about below), the running costs for either a gas boiler or an ASHP can be very similar.

You can further reduce the running costs of a heat pump by installing solar panels on your property. This means that your heat pump will be largely powered by renewable energy during daylight hours, helping to keep your running costs to a minimum. With gas prices peaking to an all time high, ASHPs are looking the much more viable option moving forward.

Average cost of replacing an existing gas boiler with an air source heat pump..

Deciding whether to replace an old gas boiler with an air source heat pump depends on a number of factors. If you own an old draughty home which costs a lot to heat then installing decent levels of insulation and cutting down on draughts would first be essential.

As we’ve previously mentioned, air source heat pumps are likely to be more expensive to initially install but there are other factors to take into consideration. If the gas boiler is quite old then there may be other parts of the system that also need to be upgraded (see table below) as gas safety regulations change over the years.

Other potential upgrades required	Approx. Cost
New condensate pipework (if old boiler is not a condensing boiler)	£150 – £250
New gas flue	£200 – £500
Replace gas supply pipe (if supply pressure insufficient)	£150 – £300

A site survey would need to be done by a Gas Safe Registered Installer, to identify if any or all of this work needed doing. Luckily, our team can sort this for you!

Upgrading of any electrical wiring, the hot water cylinder and the control system will probably need to be done with either a replacement gas boiler or a heat pump. A key question to answer is whether the radiators are of sufficient size to heat the room using the lower water temperature provided by the heat pump. If not then these will need to be upgraded in size. Pipework with an increased diameter will also be needed.

It may be smarter to spend the money on upgrading the insulation in your home, reducing the energy required to heat each room; in this case the old radiators and pipework may then be suitably sized to heat the better insulated room with a heat pump.

Boiler Upgrade scheme.

In October 2021 the UK government announced a Boiler Upgrade Scheme to help householders and small commercial owners changing from a gas boiler to a heat pump (air source or ground source). The £450 million scheme will run until April 2025 and offers a payment of £5,000 per property towards installing a new heat pump. To find out all about this scheme, read our article here!

Air Source Heat Pumps vs Gas Boilers: Maintenance.

System maintenance has and always will be critical for keeping your heating appliances in tip top condition. We recommend that you arrange for maintenance checks annually for air source heat pumps, but it is not a requirement but please remember that Maintenance will extend the lifespan and preserve efficiency of the system. Get in touch with the Heat From Air team to find the best maintenance plan for you.

Boilers however need maintenance checks annually at the very least. An effective maintenance plan can and will protect you against carbon monoxide poisoning risks. But also, old gas boilers love to play up when they haven’t been used in a while, and at the worst times.. Don’t be left in the cold this winter!

Air Source Heat Pumps vs Gas Boilers: Maintenance.

There’s no point investing in a heating method for your property if it’s unlikely to last no more than a couple of years. For this reason, it’s important to understand the expected life span of your boiler or heat pump before making the decision to invest.

A typical gas boiler will last for 10-15 years with regular maintenance before needing to be replaced. In contrast, heat pumps have an average lifespan of 20 years, with some heat pumps lasting up to 25 years before requiring replacement.

Air Source Heat Pumps vs Gas Boilers: Efficiency.

Efficiency in heating systems equates to the volume of the energy they supply that is converted into heat energy..

Energy efficiency ratings and numbers to look out for can include:

Coefficient of Performance (COP)
Seasonal Coefficient of Performance (SCOP)
Energy Efficiency Ratio (EER)
Seasonal Energy Efficiency Ratio (SEER)

Discover the meaning of these energy efficiency ratings here!

Air source heat pumps are more efficient.

Now, it’s not always going to be the ideal conditions for a heat pump to work in and outdoor air temperature can significantly affect the efficiency of an ASHP.

At lower outdoor air temperatures there is greater temperature difference between the outdoor and indoor air temperatures, and so more power input is required to generate the same level of heat, therefore reducing the performance coefficient/ratio.

The air source pump will work out cheaper long-term and you can claim much of the initial cost back through grants, but the gas boiler is cheaper up front. What’s best for you depends on your priorities, whether long-term or short-term.

Air Source Heat Pumps vs Gas Boilers: Features.

It’s important to note that gas boilers can only used for heating and hot water and not for cooling in the warmer months. Whereas most types of air source heat pump systems can be used to efficiently cool a home as well as heat it.

Air to air heat pump systems, which provide space heating through heated air, can also be very effective as a cooling system by reversing the heating process, similar to how air conditioning systems operate, and they can do this at a very efficient and effective level.

Now, a cooling system isn’t such a necessity in the UK as we don’t often have to deal with extreme weather conditions, but it is quite a nice feature to have at hand just in case. However, the UK’s leading meteorologists have warned that British summers are likely to regularly see temperatures above 40 degrees Celsius (as we saw in 2022) due to global warming issues across the planet.

Air Source Heat Pumps vs Gas Boilers: Environmental Impact.

The environment is an ongoing concern in the modern world, so there’s no wonder that many people are looking for ways to reduce their carbon footprint and installing an air source heat pump is one of the best ways to achieve this.

As we have mentioned in the efficiency section of this article, there is absolutely no competition close to the modern-day air source heat pump in terms of energy consumption. Although modern LPG, oil and gas boilers offer around 90% efficiency, as heat pumps do not use any fossil fuels whatsoever, they are currently the best option on the market.

The fact that they offer such high efficiency means that even if they use electricity derived from a coal-fired power generator, the volume of carbon emissions they’d generate would still be very minimal compared to a gas boiler.

Also opting to have heat pumps powered by green electricity such as wind or solar, can reduce carbon emissions generated to zero or close enough. Paired with mechanical heat recovery ventilation (MVHR) in commercial properties, creates an energy efficient all-in-one solution to heating and ventilation in which incredible efficiency figures can be achieved.

The MVHR system is able to recover over 90% of the heat from the outgoing stale air before feeding it back into the building as warm, fresh, filtered air. Especially during winter where the ASHP may lack in terms of efficiency, MVHR systems can increase their efficiency by up to 10%, taking that extra strain off of the heat pump.

Air Source Heat Pumps vs Gas Boilers: Space Requirements.

Traditional gas boilers don’t take up too much space. This is particularly the case with combi boilers which do not require a hot water cylinder. This makes gas boilers well-suited to small properties where space might be limited.

In contrast, air source heat pumps require a slightly larger amount of space. This is due to heat pumps requiring both outdoor space, as well as indoor for the indoor unit and a hot water cylinder. As air source heat pumps deliver heat more slowly and at lower temperatures, they can’t provide domestic hot water on demand and so must be paired with a suitable hot water cylinder.

The use of a hot water tank allows domestic hot water temperatures to be built up over time so that they’re at temperatures users would deem as ‘hot’. A hot water tank suitable for use with an ASHP system may also have one or more built-in electric immersion heaters to help keep temperatures topped up when demand for hot water is high.

A traditional gas boiler may also be used alongside a hot water tank, but the use of a combi-boiler allows hot water to be provided on demand without the need for a storage tank.

So, if you’re considering having a heat pump installed on your property, you’ll need to ensure that you have enough space available for the equipment.

Air Source Heat Pumps vs Gas Boilers: Future Proof.

With environmental issues being at the forefront, we are all being encouraged to opt for greener energy sources. With Governments promising to reach zero carbon emissions by 2050, the future looks uncertain for boilers, especially with gas boilers being banned from installation within new builds from 2025 onwards.

All gas boilers are supposed to be scrapped in the future, however, in the UK our gas network is extensive. The National Grid suggests that about 80% of British homes have a gas boiler. Transitioning all of these homes could prove difficult, but the challenge is set to improve the environment so boilers could and most definitely should be on their way out in the future.

Air Source Heat Pumps vs Gas Boilers: The Verdict.

For many years, gas boilers have been seen as the traditional way to heat your home and your hot water. However, in recent years, heat pumps have soared in popularity, thanks to their eco-friendly design, as well as their ability to reduce energy bills. Although heat pumps are becoming more popular, the UK is still lagging behind European countries such as Norway, where over 60% of properties is heated by some sort of heat pump system.

When it comes to air source heat pumps vs gas boilers, there are many factors that you’ll need to consider ensuring that you choose the right option for your property. These include cost, installation time, environmental impact, and the space that you have available. It’s important to make the right decision, as your heat pump or gas boiler will be heating your property for many years to come.

Unfortunately, if you were looking for one that stands out from the crowd as being the best, even after considering all the points above, it’s a very difficult decision. They both do a supreme job at heating properties up but one of them operates at a far superior efficiency level.

A heat pump is our recommendation if you are not connected to the mains gas supply, are constructing a sustainable property, want generally cheaper bills with less maintenance, or just want to have an eco-friendlier life. Afterall, net zero is the future so why not let your green future start here with Heat From Air.