Replacing gas boilers and the alternatives for heating and hot water


When considering the change from gas boilers to renewables, you might ask yourself ‘why?’

Our homes are a big producer of CO2, which causes global warming. The UK Government has announced that all gas boilers are to be phased out to help the UK achieve its target of becoming net zero by 2050. Decarbonising homes is one of the biggest challenges due to the fact that millions of houses will need to be retrofitted with low carbon technologies. People are still not fully aware of the low carbon alternatives on the market today and have concerns about change and taking that leap to renewables.


Replacing a gas boiler


Why are gas boilers are so popular today?

Gas boilers generate hot water for taps and radiators in your home by burning natural gas or liquid petroleum gas (LPG). If a gas boiler is fuelled by natural gas, it will be connected to the local gas network. However, if LPG powers the boiler, the fuel will be stored in a cylinder or tank and replaced regularly.

Gas boilers are the most common source of heating in the UK, with 80% of homes relying on central gas heating. To be precise, 23 million homes in the UK have a gas boiler to supply their central heating and hot water. Gas boilers are also common because they are suitable for large homes where steady hot water is in high demand. Also, the installation time is quick. They can be installed within a day, and there is no dearth of qualified gas engineers for installation.

A major factor as to why people still tend to replace their gas boilers with another gas boiler is ‘cost’. According to recent UK boiler statistics, a brand-new gas or combi boiler can be purchased for as little as £600- £2,500. The price of gas also remains relatively low. On average, one kilowatt hour of natural gas costs about 4.5 pence, which can vary depending on the tariff. All in all, gas is cheap compared to electricity, which costs around 15 pence per kilowatt hour.


How much does it cost to install a new gas boiler?

Although gas boilers seem like the easier option – in that they are more accessible and seemingly cheaper – the advantages are short-term, and boilers aren’t a long-term solution, especially because they are extremely damaging to the planet.

Despite that, by and large, people choose the easier route, and resort to installing a boiler.
However, despite the fact that a gas boiler installation is easy and quick, boilers eventually do cost more. Gas boiler installations, in fact, are both expensive and relatively complex to fit.

Firstly,  the cost: on average, a gas boiler plus installation could cost £4000-£4500 depending on the make and type of model you have. You also must be careful, as the cheaper the boiler, the less powerful it is going to be and will only be suited to smaller properties. A 24-30kW boiler is suitable for any home with up to three bedrooms, whereas larger houses require a boiler that is 35kW and above. The most expensive and powerful options available are biomass boilers, costing around £12,000, followed by condensing boilers at £3,000. Regardless of the power though, both kinds of boilers still release greenhouse gases.

Secondly, gas boilers can last up to 15 years or more depending how often they receive maintenance or servicing. In a blog from Vaillant, they said “We can’t stress enough the importance of an annual service from a gas safe registered (GSR) engineer, even if you believe your boiler is running smoothly”. For an annual service cost for a gas boiler in the UK, you will be looking to pay in the range of £130. So over 15 years, this will cost you an additional £1950 on top of your boiler and installation.

If your boiler is older, you may already have a build up of limescale or excessive sludge. This can cause significant damage to the central heating system and lead to your gas boiler breaking down. This issue can be resolved by a GSR engineer with a power flush which can take anywhere from 8 hours to 2 days and could cost between £400 and £900. This is compulsory if you want your gas boiler to prolong its lifespan as much as possible.

Gas boilers may also come with health problems. One of the biggest health risks associated with boilers is Legionnaires’ disease. When legionella bacteria infest a person’s lungs, it can lead to flu-like symptoms, difficulty breathing, chest pains and hospitalisation, and can be fatal. Gas boilers and central heating systems can host legionella bacteria as they store water. Even people with more modern combi boilers can still become infected with the deadly disease, as it can develop in spa and whirlpool baths.


Is natural gas as bad for the environment as fossil fuels?

All these extra costs adding up still don’t become the biggest issue about using gas boilers. The environmental damage is the dearest concern.
With 95% of UK homes being centrally heated, the majority rely on gas boilers, which release CO2, a greenhouse gas. Most CO2 emissions come from the burning of fossil fuels, with heating contributing almost 30% of the UK’s total greenhouse emissions and about half of these from heating your home.

Due to the impact of gas boilers on climate change, the UK Government has announced its plan to decarbonise the nation and phase out gas boilers by 2035. The International Energy Association’s latest report stresses that no new boilers should be sold after 2025 if net zero targets are to be achieved by 2050. As part of the ‘Boiler Upgrade Scheme’ to promote clean heat from low carbon technologies, £7500 government grants are available to UK households.


Switching to renewables and the challenges

The UK government has backed ground- and air-source heat pumps as the preferred alternative to gas boilers for households looking to switch. Heat pumps run on electricity, are extremely efficient, and can be retrofitted.
Here’s the thing though – combi boilers take up very little space in homes, so as imperative as it is, making the switch to heat pumps can be extremely hassling once you factor in the space needs of a bulky hot water cylinder for hot water storage.

To address that challenge of unlocking space when switching to renewables, Sunamp’s Thermino heat batteries become the perfect hot water solution, because unlike a hot water cylinder or a tank, Thermino heat batteries contain Plentigrade phase change material, which allows storing 4x energy than an equivalent hot water tank. Also, it delivers mains pressure hot water on demand.

Also, because of the exceptionally high-energy density, the Thermino heat battery can be up to four times smaller than the equivalent hot water cylinder as the batteries don’t have to store any water inside, and they can be neatly fitted into a small space in your home.
Additionally, thanks to high-powered vacuum insulation, heat losses from Thermino batteries is much lower than a regular hot water cylinder. Depending on how old your hot water cylinder is, you may be losing 1.344-3.336 kWh of heat daily, whereas the average heat loss rate of a Thermino is only 0.77 kWh daily saving up to 1000 kWh of electricity each year, and as much as £282 based on the current energy price. This is down to the fact they are up to four times more energy efficient and have an A+ energy rating.

Thermino heat batteries also don’t need any annual servicing as they have no moving parts, saving you money over the years as there’s no maintenance required after the unit is installed. Every battery is under a market-leading 10-year warranty, and the PCM inside has failsafe performance to over 40,000 cycles, equivalent to 50 years of daily use. As the heat batteries do not store water, they are protected against legionella risk, when installed according to the manufacturer’s instructions. And there’s need to heat the water to high, bacteria-busting temperatures, reducing both costs and energy emissions. Plus, the batteries are non-toxic & non-flammable, and every component used in making them is fully reuseable or recyclable at the end of life.
They replace a standard hot water cylinder and are flexible with the energy source – they can work with boilers, mains electricity, heat pumps and solar panels to reduce energy use.



For a more detailed comparison, read our blog: Hot water cylinder vs Thermino – which hot water system is right for you? | Sunamp | Global – World leading thermal energy storage technologies

If you’re a homeowner looking to future-proof your house, get in touch with us here to get started.