Green Alternative to Gas Boiler Systems Guide | Achieve Low Carbon Heating in 2023

Need an eco friendly alternative to gas boiler heating for your home or business? Of course you do! After all, the UK’s gas boiler ban of 2025 is right around the corner. We get you sorted out in our gas boiler replacement guide below.

Are you thinking about ditching your gas boiler? With 4 million UK households living off our coveted gas-grid, it’s conceivable that you may find yourself living where there’s no mains gas; or, perhaps you’re looking to outpace the impending gas boiler ban of 2025 and get on board with green technology.

Whatever the reason, there are many alternative types of boilers to gas boilers, and we discuss them all right here in the post; keep reading to find out more!

What are the main options for a gas boiler replacement?

If you’re thinking of getting rid of a gas boiler or simply don’t want to buy a new one, there are many other types of central heating systems:

Some of these are renewable:

• Biomass boilers
• Air-source heat pumps
• Ground source heat pumps
• Water source heat pumps
• Solar panels
• Hybrid heating systems

Others rely on fossil-fuels:

• Oil-fired boilers
• LPG-fired boilers
• Electric heating

Which eco friendly gas boiler alternative gives low carbon heating?

If you already in the market for a boiler replacement, there are plenty of good reasons to swap it for a green alternative. With the 2025 boiler ban and the 2050 net-zero emissions target approaching, you can expect fossil fuels to come under a lot of pressure from the Government soon. Why wait if you can already start reducing your CO2 emissions in a meaningful way, and possibly qualify for government incentives? 

Here’s a look at a few viable eco boiler options.

Biomass boilers

Biomass boilers work the same way most boilers do: they heat water, which then circulates the radiator network and serves the taps. Unlike their fossil-fuel cousins, though, they run on a renewable, carbon-neutral fuel: wood. It’s renewable because the species used for biomass fuels can grow back at a pace that keeps up with consumption. And it’s carbon-neutral since burning wood gives off only the carbon the trees absorbed during their lifetime and nothing additional. Thus, biomass boilers are a suitably green alternative to gas boiler home heating systems.

But like all other heating systems, biomass boilers have some pros and cons.

The most obvious pro is that the fuel source is cheap and clean. A wood pellet-fired device costs about the same to operate as a gas boiler. Wood chip and log boilers are even cheaper to run. As they combust their fuel, these machines emit on average 550-800 kg of CO2 into the atmosphere – a far cry from their fossil-fuelled variants.

Their 2 biggest, deal-breaking flaws are their size and maintenance demands. These machines can be 3-4 times as large as gas boilers, and you’ll need to find space for their fuel. And with burning wood come ash and soot that you’ll have to clean regularly.

Now let’s look at the costs.

How much does it cost to get a biomass boiler?

Biomass boilers are not cheap. OK, in theory, you can find a hand-fed stove for £1,000 or less. Any respectable model, though, will set you back anywhere between £5,000 and £13,000, or even more. The total price to install a boiler that runs on biomass depends on the level of automation, fuel type, and whether or not you need a new flue with the boiler (a chimney alone won’t qualify).

The good news is that if you get your new biomass boiler up and running by 31 March 2022, you may qualify for the Renewable Heat Initiative (RHI). The RHI is a Government scheme meant to put precious heating money back in your wallet if you use a gas boiler alternative which works on renewable fuel. Upon enrollment, the scheme will reimburse you quarterly for 7 years.

How much does it cost to run a biomass boiler?

They cost about the same to run as a gas-fired boiler. So the dwellers of that 3-bedroom house would be looking at £900 or so in annual heating costs. That said, when paired with a good thermal storage tank, or solar water heating, the boiler’s output could be reduced, thus slashing fuel use.

To summarise: biomass boilers are costlier than most fossil-fuel boilers but are on the low-end of the scale in running costs. They give off way less CO2 emissions, and even those are carbon-neutral. On the flip side, these machines (and their fuel) take up lots of space and demand frequent upkeep.

All that being said, if you’re living off the grid in an isolated area, chances are you’ll have plenty of space to accommodate these giants and their fuel.

Heat pumps

In light of the coming fossil-fuel phase-out, the Government touts heat pumps as the UK’s path to a net-zero future. Their other options are heat networks, fuel cells, and electric heat – far-fetched, space-age, and pricey means, respectively, if they’re to replace fossil fuel heat in the next few years. Curiously, the clean, green, carbon-neutral biomass boilers don’t seem to fit into the decarbonisation plans. So in the face of this credulity, we must ask: can heat pumps make a clean, viable gas boiler replacement?

Spoiler alert — yes, they can!

First, let’s try to understand:

What are heat pumps?

It’s rather simple. If you’re in your kitchen now, you’ve probably got a heat pump humming even as you read these words; that’s right – your fridge. Yet another heat pump probably hangs off your building’s wall or sits on the ground below. You got it again – the air conditioner!

These systems have served us for decades. To date, we’ve used them mostly to acquire cold. But what’s cool about these contraptions is that they can readily reverse their cycle and produce heat.

Here’s what a heat pump does: It circulates refrigerant between 2 coils. In one, the liquid evaporates and absorbs the surrounding heat; in the other, it condenses and releases the heat where we tell it to. Simple as that!

There are 3 types of heat pumps:

• Air-source
• Ground-source
• Water-source

Let’s examine each and see how they compare.

1. What are air-source heat pumps?

When in cooling mode, a heat pump takes heat from the indoor air and moves it outdoors, exactly like an A/c. In the heating mode, just imagine your A/c running in reverse – taking heat from the outdoors, and sending it into a home. Naturally, you’ll ask ‘but if I’m heating, isn’t it cold outside to begin with?’ And you’re right – the winter air temperature may hover around zero in the UK. Yet, a heat pump can still pluck heat from the frigid air, by simply cycling an even colder refrigerant.

An air-source heat pump comprises a fan – similar to an air conditioner – and a heat distribution system. Because air-source heat pumps supply cooler heat than boilers, they work best with either a network of large radiators or radiant flooring. These pumps are most efficient in well-insulated homes that have low rates of heat loss through walls and windows.

2. What are ground-source heat pumps?

AKA geothermal heat pumps, they work the same as their air-source equivalents. But, instead of drawing heat from the outdoor air, they get it from the ground. The method is more efficient, as soil retains rather balmy temperatures of 10-15C even as the air above it chills to below 0 C. This means that the pumps can harvest more heat with less effort–a truly viable alternative to gas boiler systems.

Unlike the air-source units, these geothermal heat pumps produce high heat, can be used with standard radiators, and supply hot water to your taps.

3. What are water-source heat pumps?

As their name suggests, water-source heat pumps take in heat from the water. Apart from this, they function just like a geothermal unit.

To run this device, you must be close to a natural body of water, such as a river, lake, or well. Due to this constraint, water-source heat pumps are not practical for most homes.

Now that you’re familiar with the 3 variants of heat pumps, let’s see what it costs to get and run one of these low carbon heating systems.

How much does it cost to get and run a heat pump?

That depends on the pump’s efficiency, your home’s heating needs, and the insulative properties of your walls and windows, and the source of heat.

Air-source heat pump costs

Air-source heat pumps tend to be the cheapest, as they require the least infrastructure and labour to install. They’re simply an A/c unit that can run in reverse. With installation (remember those bulky radiators needed to keep you warm with low heat?), these systems cost anywhere between £7,000-£12,000.

Typical air-source heat pumps produce about 3 kW of heat for every 1 kW of electricity – this factor is known as the Coefficient of Performance (COP). So with an average home needing 15,000 kW in heat every year, the power consumption would equal 5,000 kW. With electricity costs at 14p./kW, the total for the year is £700; not too bad. In our example 3-bedroom house, however, the heating costs will nearly double to £1,200.

Keep in mind: these numbers are not cut-and-dry. Your home’s insulation efficiency and rate of heat loss will also factor into your annual heating bill.

Ground-source pumps are easily double, or even triple, the cost of their little air-source cousins. Because you have to dig underground to install the piping network, you’d be looking at a supply-and-install total of £15,000-£40,000.

Running a ground-source heat pump can cost a bit less, even though they supply hot water to your taps. That’s because their COP is higher than that of air-source pumps, at 4 on average. With a COP of 4, heating a 3-bedroom house could cost £800-£1,000 per year.

Again, you can probably drive this number down even more with well-insulated walls, triple-pane windows, and a higher COP model.

Water-source heat pumps take less effort to install than their ground-source counterparts. While total costs will range wildly depending on the model and your local water source, these units have an average price tag of £10,000-£15,000.

The running costs should be similar to those of GSHPs, thanks to these units’ stellar COP.

Don’t forget: the RHI scheme we mentioned earlier will reimburse you for the energy your heat pumps generate. So, if you’re considering ditching your gas boiler for one of these renewable heaters, do it before 31 March 2022, which is the RHI enrollment deadline.

Solar Heating

Even in our cloudy nation, solar heat and power systems are quickly gaining steam as an eco boiler alternative. Per the Solar Trade Association, close to a million UK homes already have solar panels on their roofs. With rising electricity rates and falling panel prices, the trend is likely to persist.

Here’s what’s great about solar systems: with correct pitch and orientation, their photovoltaic (PV) panels can absorb the sun’s rays in any weather. The power they produce can not only supplement your electricity needs but also heat water; and if you already have a regular gas boiler, you can hook up your solar system to it without too much fuss.

Just bear in mind that while your PV panels will help reduce your overall heating costs, you will pay a large chunk of money to get them installed in the first place. And you’ll need 300 ft2 of these panels to make the expense worthwhile.

As of 2020, the solar thermal panel costs in the UK range between £3,000 and £6,000, depending on the system size, model, and placement. One thing to consider is that solar panels will generate less heat on colder, shorter winter days; so treat them as a secondary heat source for those months.

Hybrid Heating Systems 

Hybrid heating systems combine the efficiency and sustainability of heat pumps with the reliability of gas boilers. Just like hybrid vehicles, these systems automatically alternate between the ‘heat pump’ and ‘boiler’ modes, depending on which is the most efficient at the time. Typically, the heat pump will operate in warmer weather, letting the boiler take over when the mercury drops substantially. This way, you can balance comfort, costs, and sustainability, and always rest assured that your trusted boiler friend is there for you if the more novel, sustainable heat pump suddenly gives up the ghost. 

On the downside, hybrid systems are rather expensive. This shouldn’t be a huge surprise — you’re buying and installing a boiler, a heat pump, and a mechanism that alternates the alternative heating modes. Don’t forget that since these systems do rely on natural gas, you won’t be reducing your CO2 emissions as drastically as you could with solar panels or heat pumps alone. 

The challenges involved with green alternatives to gas central heating

The primary obstacle in the way of anyone trying to do away with fossil fuel heating is costs. Mind you, prices of renewable technologies have slumped significantly since their early days, as supply has surged to keep in step with the ever-increasing demand. What’s more, the UK government has incentivised conversions to green heating through various grants. 

But ultimately, it’s always cheaper to install a gas boiler than the much-cleaner heat pump. And this simple calculation is what keeps many Britons — even those who aspire to slash their carbon footprint — from going through with the change. 

The novelty of these green alternatives is yet another factor. While they’re quickly gaining acceptance, there’s still plenty of resistance from people who have relied on boilers for generations and find it difficult to take a leap of faith with something new (and more expensive). 

As time goes on, hopefully these hurdles will erode. Government incentives — and legislation — have so far done well in warming up the British public to the idea of sustainable heating options. 

In the meantime, remember this — though they cost more upfront, renewable heating methods are far more efficient than their fossil-fuel alternatives. That’s why their long-term use will eventually offset the higher costs. 

And if you’re just not ready to fully ditch your boiler in favour of a heat pump, you can always consider a hybrid heating system, which would let you use both options.  

What are the fossil-fuel alternatives to gas boilers?

If you really feel that switching to renewable heating methods isn’t practical for you at the moment, don’t worry. There’s currently no law on the books that forbids oil and LPG heating. And although these non-gas variants tend to cost more to operate, there are certain cases where they may be preferable to gas boilers. Let’s take a look.

1. Oil-fired boilers

How do oil boilers work?

Much the same as gas. These boilers burn oil in a combustion chamber to heat water, which then circulates your home’s network of radiators and hot water taps.

Just like gas-fired boilers, oil boilers come in conventional and combination varieties. These give you the option of heating lots of water at once to supply a large household, or having hot water on demand.

One key distinction is that oil boilers have their fuel source stored on site. There are pros and cons to this.

The notable advantage is that you don’t have to rely on a municipal connection – you get your fuel delivered, and it’s stored until you need to fire up your boiler. So if you live in a remote or rural area with no connection to the gas grid, oil is the logical alternative.

On the other hand, if your property is small enough, fitting in a large tank of oil may be problematic. You may also be averse to storing large quantities of a flammable liquid so close to home.

Unfortunately, oil boilers produce substantially more CO2 emissions than their natural gas-fired counterparts. While an average residential gas boiler emits roughly 6 tonnes of CO2 annually, an oil-fired boiler with the same capacity produces closer to 9 tonnes of CO2 in the same time frame. That’s 50% more CO2 that gets released, and trapped in the Earth’s atmosphere. 

How much does it cost to buy an oil boiler?

With installation, oil boilers cost in the neighbourhood of £2,500-£5,000. Seeing how a gas combi boiler from Heatable starts at £1,695, the oil alternative certainly seems more expensive. That said, if you’re off the gas grid, oil boilers are still reasonably priced compared to some other options we will discuss here.

How much does it cost to run an oil boiler?

Heating with oil costs about 5.2p/kW. With this figure in mind, we can see that an average home in the UK would spend about £780 annually; that’s based on a yearly consumption of 15,000 kW. Now, a 3-bedroom house, which is likelier in a remote, off-the-grid setting, will cost roughly £1,350 to heat with oil every year. That’s drastically more than the £900 it takes a gas boiler to keep a home of the same size warm. On a side-note, modern, condensing oil boilers are super-efficient; most have an efficiency of 92-93%, so only 7-8p. gets lost for every £1 you pay for the fuel.

To summarise: if you’ve no means of connecting to a gas mains, oil boilers are a moderately pricier, but reasonable alternative to gas boiler systems. If you do have mains gas, then there’s little reason to consider switching to oil heating (unless, of course, you have a grudge against your gas company). Keep in mind, too, that oil combustion emits 50% more greenhouse gases than natural gas. As a temporary — and in some cases, unavoidable — solution, an oil boiler might make sense; but if you’re serious about fighting climate change, then this heating method is really not the way to go.

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2. LPG-fired boilers

OK, so oil heating is dirtier AND more expensive. But what about Liquified Petroleum Gas (LPG)? Won’t that work for off-grid homes? Let’s have a look.

How do LPG boilers work?

LPG boilers work just like their oil and gas equivalents. In fact, many gas boilers can be easily converted to run on LPG (please don’t try to do this yourself). As with oil, LPG is usually brought to the customer and kept in a storage tank. This portability makes LPG a grand option for those of us living without mains gas.

You may ask the obvious now: how does LPG compare to oil as a boiler-fuel? LPG has several unique advantages.

For one, LPG is cleaner than oil. When burnt, it gives off roughly 15-20% less Carbon Dioxide, and on an annual basis, you’re looking at 1.5 tonnes less emitted CO2.  What’s more, these boilers operate at about 90% efficiency, so for every £1 you spend heating, only 10p gets wasted.

As well, LPG boilers cost way less than those that run on oil or gas. Oh, and as we mentioned, most gas boilers can be converted to accept LPG. So if you’re moving from the city to an off-grid area, you may be able to bring your gas boiler and modify it to run on LPG.

One major downside is the higher cost of fuel; your wallet will definitely feel a conversion from gas, or even oil, to LPG.

How much does it cost to buy an LPG boiler?

You can find one a lower-end unit for a measly £350, while a top-tier Worcester Bosch can still set you back over £2,500. Then there’s everything in between, and these mid-range LPG options are notably more economical than their gas or oil counterparts.

Searching for LPG boilers? Check install prices on Heatable

How much does it cost to run an LPG boiler?

Currently, the cost of heating with LPG is 6.64p./kW. With an annual power use of 15,000 kW, the bill works out to £996. With our 3-bedroom example home, however, the heating bill skyrockets to £1,725; noticeably more than oil, and substantially more than gas.

To summarise: if you’re living off the country’s gas grid and prioritise a cleaner fuel source over running costs, LPG heating may be right for you. Even financially, though, it’s not all bad news: LPG boilers cost less to buy and install, and your existing gas boiler may be converted to run on LPG if you’re moving someplace remote.

3. Electric heating

You may notice that we’ve kept electric boilers in the fossil-fuel section. It’s no accident – the UK’s power generation is largely done with fossil fuels. As such, we simply can’t call electric heating ‘green’ or ‘sustainable’. That said, electric heating appeals to many, so let’s find out why. But first:

How does electric heating work?

There are 2 ways to heat your home with electricity. You can use an electric boiler to heat water as you would with any other boiler. That said, these boilers have a limited capacity for heating water, so the option will not work with larger homes.

Alternatively, you may use electric storage heating. These systems work at night to exploit the cheaper rates, then store heat and gradually release it during the day.

Are there benefits to electric heat? Yes, there are. Unlike gas, mains electricity is more available throughout the UK, so even a remote rural area is simple enough to heat.

But the 3 major cons seem to outweigh the pros:

1. Per kWh, electricity is considerably more expensive than other fuels; and
2. The more efficient electric storage heaters leave your house cold in the evening.
3. A good portion of the UK’s electricity is still produced by burning fossil fuels, so this heating method really isn’t as ‘clean’ as it seems.

How much does it cost to get an electric heater?

Smaller, 9kW combi boilers cost on average £1,500. Meanwhile, high-power, efficient premium models command a price of over £4,000.

If you’re looking for a storage heater, you can find a mid-range, 2kW model for less than £1,000. Just keep in mind that you’ll need several of these to keep all areas of your home warm – as you would with radiators.

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How much does it cost to run an electric heater?

If you’re heating with an electric boiler, you’d be paying 14p/kW. So an average household would spend £2,100 on their annual heating needs. The 3-bedroom house would not get enough hot water to maintain comfortable temperatures, so we’ll leave it out of the equation – there are no electric boilers to heat such a large property.

So, our next option is electric storage heaters. With night-time tariffs, these machines could, in theory, give you heat all year for just £800. The problem with storage heaters is they release heat all day and cool off by the evening when you crave warmth the most.

To summarise: electric heat is a viable alternative to remote dwellers willing to splurge on electricity, or a smaller household with minor heating needs. However, it’s not the cheapest, nor the most sustainable way to heat homes. 

So, what is the best alternative to gas boiler heating systems for you?

To wrap up, let’s go over all of our gas boiler alternatives, and see which one may suit your needs best.

1. Biomass boilers

Comparable to gas boilers in running costs, these heaters are truly green, as their fuel source is renewable and carbon neutral. Sadly, biomass boilers may be out of reach for many, chiefly city dwellers, who just don’t have the room to fit them in their homes. For folks living in off-grid areas with plenty of on-site storage space, biomass boilers may be a worthwhile, albeit costly investment.

2. Heat pumps

Heat pumps are a viable, green(ish) alternative to gas boiler systems. But they have one major flaw – they cost a small fortune. While the more economical air-source units come with a lower price tag of £7,000-£12,000, they work best in newer homes that don’t leak heat. Their more robust ground-source equivalents cost more, possibly setting you back as much as £40,000 for a high-capacity, top-efficiency unit. Water-source heat pumps are more affordable but are only practical if you live close to a natural body of water.

All that being said, efficient heat pumps, paired with well-insulated walls and windows, can incur lower running costs than gas boilers, and save you money over time. Just be willing to spend more upfront.

3. Solar panels

Solar panels are taking the world by storm. Just this year, California became the first US jurisdiction to mandate solar panels on all new build homes. Granted, those folks get more sun than us, but luckily solar panels work on cloudy days too. With over 800,000 UK household already using solar panels for power and heat generation, you can expect this technology to become even more accessible and cost-efficient in years to come.

If you’re thinking about scrapping your gas boiler for solar panels, though, think again. While they’re a brilliant source of heat during long summer days, they are much less useful during winter. So, instead of relying on them as a primary heat source, you can install solar thermal panels and hook them up to your conventional boiler to supplement your heat and power needs.

One last thing you shouldn’t forget: solar panels need roof space. Make sure you get a professional to assess your property and confirm whether you can install a sufficiently sized solar system that’s worth your money.

4. Oil boilers

Are you living in a remote location, off the gas grid?

Then an oil boiler is a logical pick. Oil boilers let you heat at only slightly higher costs than gas while relying on stored fuel.

On the downside, you have to bother with fuel deliveries and keeping a flammable substance on your property. As well, oil gives off a sizeable amount of Carbon Dioxide as is burns; way more than gas or even LPG. So if you’re at all concerned about your carbon footprint, oil boilers may not be the best choice for you.

5. LPG boilers

Very similar to oil boilers in terms of portability, they let you live off the grid. On the upside, LPG boilers cost less, and most existing gas boilers can be converted to use LPG. Another benefit is the lower CO2 emissions compared to oil. On the downside, you’re looking at higher fuel costs and having to store flammables near your home.

6. Electric heaters

Electric boilers rely on a very expensive source of power to operate, and most units are not designed to heat large homes. The alternate, electric heat storage devices, cost less to run, but supply heat for only a portion of the day, leaving your home cool in the evening just as you’re ready to go to bed. Perhaps their only advantage is their portability. In a small house off the gas mains system, an electric storage unit may serve as a handy, economical heat source.

Best alternative to gas boiler guide: Parting words

If you’re not ready to ditch your gas boiler just yet, have a look at Heatable’s selection of regular, system and combi units here. Otherwise, pay careful consideration to the options we’ve covered today. Each will still be around to survive the gas boiler ban of 2025, and will provide an alternative heat that keeps you warm and your carbon footprint small.

To be sure, the switch to eco heating systems won’t be cheap, but in the long run it will be far more economically and ecologically resilient.

Do you have any questions about a specific alternative to gas boiler systems? What do you know about what will replace gas boilers in 2025? Leave us your thoughts in a comment below.

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