When it comes to oil boiler vs gas boiler, a gas boiler is usually cheaper to buy, simpler to live with and cleaner to run, while an oil boiler is the most practical choice for homes that are not connected to the mains gas network.
Both can be over 90% efficient, both can heat a large family home with ease, and in 2026 the running costs per unit of heat are closer than many people think. The real difference comes down to where you live, what fuel you can get, and how you feel about storing fuel in a tank in your garden.
Here in Kent, that choice is very real. Thousands of homes in towns like Maidstone, Dartford and Ashford run on mains gas, while villages across the Weald, Romney Marsh and the North Downs still rely on heating oil.
This guide sets out the costs, the pros and cons, and a head to head comparison so homeowners and landlords can make a clear, confident decision.
Oil Boiler vs Gas Boiler: A Quick Comparison
When deciding between an oil boiler or gas boiler, it comes down to a trade off between cost and convenience: gas wins on installation price, ease and carbon emissions, while oil wins on independence from the gas grid. The table below sums up the key differences at a glance, and we go into each point in more detail further down.
| Factor | Oil Boiler | Gas Boiler |
| Best suited to | Homes off the mains gas grid | Homes on the mains gas grid |
| Efficiency (modern condensing) | Around 90% to 93%, ErP A rated | Around 92% to 94%, ErP A rated |
| Typical fitted price (2026) | £3,500 to £6,000, plus £2,000 to £4,000 if a new tank is needed | £2,200 to £4,300 |
| Running costs | Similar per unit of heat, but oil prices rise and fall with no price cap | Similar per unit of heat, covered by the Ofgem price cap, plus a daily standing charge |
| Heating and hot water performance | Very powerful, ideal for large homes | Very powerful, with the widest choice of combi, system and regular models |
| Reliability | Robust, but more moving parts to look after | Very reliable, with parts and engineers easy to find |
| Typical lifespan | 15 to 20 years | 10 to 15 years |
| Annual service cost | Around £120 to £200 (OFTEC engineer) | Around £80 to £120 (Gas Safe engineer) |
| Manufacturer warranty | Usually 5 to 10 years | Usually 5 to 12 years |
| Which? ratings | Which? rates brands, not fuel types. Fewer oil boiler owners are surveyed, so oil brand data is thinner | Leading gas brands such as Vaillant, Viessmann and Worcester Bosch regularly score well in Which? reliability surveys |
| Trustpilot ratings | Main oil brands such as Grant and Worcester Bosch generally receive positive reviews | Major gas brands generally rate Good to Excellent on Trustpilot |
| Fuel supply | Delivered by tanker and stored on site | Piped in continuously from the mains |
| Space needed | Boiler plus an outdoor oil tank | Wall mounted boiler only (combi) |
| Carbon emissions | Higher, around a third more CO2 per unit of heat | Lower than oil |
| Main safety concern | Oil leaks, spills and tank theft | Gas leaks and carbon monoxide |
| Future outlook | Can be adapted to run on renewable HVO fuel | Gas boilers remain allowed in existing homes, with no ban on replacements |
Ratings and review scores change over time, so it is always worth checking the latest Which? and Trustpilot pages for the exact brand you are considering.
Not sure which fuel suits your home? Guscott Heating installs gas boilers across Kent and the wider South East. Our Gas Safe registered engineers will give you honest advice on which boiler makes sense for your property. Request your free boiler quote and get a clear price today.
Oil Boiler vs Gas Boiler: Which Is Better?
There’s no single winner for every home: a gas boiler is better if you are on the mains gas grid, and an oil boiler is better if you are not and want a powerful, independent heating system. Below we look at why people choose each one, the honest pros and cons, and who each boiler suits best.
Why Choose an Oil Boiler
An oil boiler burns kerosene (often called heating oil or 28 second oil) to heat your radiators and hot water. The oil is delivered by tanker and stored in a tank in your garden or driveway. Around 1.5 million UK homes use oil heating, mostly in rural areas where the gas network never reached.
In Kent, oil boilers are common in villages around Cranbrook, Tenterden, Romney Marsh, Lenham and the countryside near Sandwich and Faversham. For many of these homes, oil is still the most affordable way to get strong, reliable central heating.
Modern oil boilers are condensing models, which means they recover extra heat from the exhaust gases and turn more than 90% of the fuel into useful heat. You can get oil combi, system and regular boilers, along with external models that sit outside the house in a weatherproof casing to save indoor space.
Well known oil boiler brands include Grant, Worcester Bosch, Firebird and Warmflow.
Pros & Cons of Oil Boilers
| Pros | Cons |
| Works anywhere, with no need for a mains gas connection. | Higher upfront cost than a gas boiler, especially if the tank needs replacing. |
| Very high heat output, which suits large, older or draughty country homes. | Oil prices are not capped and can jump sharply, as they did in 2022. |
| Modern condensing models are over 90% efficient. | You have to keep an eye on your tank level and order deliveries. |
| No daily standing charge, as you only pay for the oil you order. | Running out of oil leaves you with no heating or hot water. |
| You can shop around between suppliers and buy when prices dip. | The tank takes up outdoor space and can be a target for thieves. |
| Tend to last a long time, often 15 to 20 years with good servicing. | Higher carbon emissions than gas. |
| External boiler options free up space inside the house. | Servicing usually costs more, and fewer engineers are OFTEC registered. |
| Can be adapted to run on lower carbon HVO fuel. |
Should You Choose an Oil Boiler?
Choose an oil boiler if:
- Your home is not on the mains gas grid and a connection would be very expensive.
- You already have a good oil tank in place and want a like for like replacement.
- You live in a large or poorly insulated rural home that needs a lot of heat.
- A heat pump is not practical right now because of cost, insulation or space.
Do not choose an oil boiler if:
- Mains gas is already connected or can be connected at a sensible price.
- You have no suitable outdoor space for a fuel tank.
- You want the lowest possible carbon footprint.
- You would rather not manage fuel orders and tank checks.
Why Choose a Gas Boiler
A gas boiler burns natural gas supplied through the mains network, which in Kent is run by SGN (Southern Gas Networks). It is by far the most common type of heating in the UK, used in around 85% of homes. The gas arrives through a pipe on demand, so there is nothing to store and nothing to order.
Most towns across Kent are well served by mains gas, including Chatham, Gillingham, Canterbury, Margate, Folkestone, Tonbridge and Gravesend. If your home has a gas meter, a gas boiler is almost always the simplest and cheapest option.
Gas boilers come in three main types: combi boilers for smaller homes, system boilers for homes with two or more bathrooms, and regular boilers for older homes with a loft tank.
Because so many are installed, there is a huge choice of models from brands such as Worcester Bosch, Vaillant, Viessmann, Ideal and Baxi, and plenty of Gas Safe registered engineers to fit and service them.
Pros & Cons of Gas Boilers
| Pros | Cons |
| Cheaper to buy and install than an oil boiler. | Only an option if your home is on, or near, the gas grid. |
| Continuous fuel supply, so you never run out. | You pay a daily standing charge whether you use gas or not. |
| Prices are covered by the Ofgem energy price cap, which smooths out the worst spikes. | Gas leaks and carbon monoxide are serious risks if the boiler is badly fitted or not serviced. |
| Compact wall mounted boilers with no outdoor tank. | Typical lifespan is a little shorter than oil, at 10 to 15 years. |
| The widest choice of boilers, controls and smart thermostats. | Still a fossil fuel, so it is not the long term low carbon solution. |
| Plenty of Gas Safe engineers, so servicing and repairs are quick to arrange. | |
| Lower carbon emissions than oil. | |
| Long manufacturer warranties, often up to 10 or 12 years. |
Should You Choose a Gas Boiler?
Choose a gas boiler if:
- Your home already has a mains gas supply.
- You want the lowest upfront cost for a new boiler.
- You live in a flat, terraced house or home with little outdoor space.
- You want a no fuss system with nothing to order or monitor.
Do not choose a gas boiler if:
- Your home is far from the gas main and a new connection would cost thousands.
- You are ready to move to a low carbon option such as a heat pump.
- You want to avoid standing charges entirely.
Oil Boiler vs Gas Boiler: Head to Head
Oil boiler vs gas boiler head to head shows gas winning on most everyday measures, while oil holds its own on lifespan and fuel independence. Here is how they compare point by point, with a clear winner for each.
Efficiency
Modern oil and gas boilers are both condensing boilers, so both carry an ErP A rating. A good gas boiler typically converts around 92% to 94% of its fuel into heat, while a modern oil boiler sits at around 90% to 93%. In real life the gap is small, and how well the boiler is sized, set up and controlled matters far more than the fuel.
A gas or oil boiler running at a lower flow temperature with weather compensation will beat a poorly set up model of either type. Old non condensing boilers are a different story. A 20 year old oil or gas boiler may only be 65% to 75% efficient, so upgrading either one makes a noticeable difference to your bills.
Winner: Gas boiler, by a small margin.
Installation Cost
A new gas boiler typically costs £2,200 to £4,300 fitted in Kent, depending on whether it is a combi, system or regular model. A new oil boiler typically costs £3,500 to £6,000, because the boilers themselves cost more and the work must be done by an OFTEC registered engineer.
The oil tank is the big extra. If your tank is old, single skinned, cracked or too close to the house, a new bunded tank usually adds £2,000 to £4,000. Tanks generally last 20 to 30 years, so check its age before you budget.
| Cost Item | Gas Boiler | Oil Boiler |
| Typical fitted price in Kent | £2,200 to £4,300 | £3,500 to £6,000 |
| New oil tank (if needed) | Not needed | £2,000 to £4,000 |
| Total including a new tank | £2,200 to £4,300 | £5,500 to £10,000 |
| Engineer required | Gas Safe registered | OFTEC registered |
| Tank lifespan | Not applicable | 20 to 30 years |
The “Total including a new tank” row isn’t in your original text. I added the oil boiler and tank figures together (£3,500 + £2,000 to £6,000 + £4,000), so delete that row if you’d rather keep to the figures already in the copy.
Winner: Gas boiler.
Running Costs and Fuel Prices
Oil and gas cost roughly the same per unit of heat most of the time. At the time of writing, mains gas costs around 6p to 7p per kWh under the Ofgem price cap, while heating oil at 60p to 75p a litre works out at roughly 6p to 7.5p per kWh. Prices change, so treat these as a rough guide.
| Running Cost Factor | Gas Boiler | Oil Boiler |
| Fuel price per kWh | Around 6p to 7p | Around 6p to 7.5p |
| Fuel price | Capped by Ofgem, reviewed every 3 months | Heating oil at 60p to 75p a litre, with no price cap |
| Standing charge | Around £100 or more a year | None |
| Price stability | Steadier and more predictable | Can spike sharply (more than doubled within weeks in 2022) |
| Money-saving tip | Limited, as prices are capped | Buy in summer when prices are often lower |
| Fuel cost for 12,000 kWh a year | £720 to £840 | £720 to £900 |
| Estimated annual bill including standing charge | £820 to £940 | £720 to £900 |
The bigger difference is how prices behave. Gas prices are capped and reviewed every three months, but you also pay a daily standing charge of around £100 or more a year. Heating oil has no price cap and no standing charge, so you can save money by buying in summer when prices are often lower, but you are also exposed to sudden spikes. In 2022, oil prices more than doubled within weeks.
For a typical three bed home in Kent using around 12,000 kWh a year, annual fuel bills for oil and gas usually land within a hundred pounds or so of each other.
Winner: Gas boiler, for steadier and more predictable bills.
Heating and Hot Water Performance
Both oil and gas boilers can comfortably heat large homes and supply plenty of hot water. Oil boilers often come in higher outputs, which suits big detached farmhouses and older stone or brick homes in the Kent countryside that lose heat quickly.
Gas has the edge on choice. There are far more gas combi, system and regular boilers to choose from, in every size, so it is easier to find a model that matches your home exactly. Gas combis also tend to deliver hot water a little faster than oil combis.
Winner: Draw. Oil for very large rural homes, gas for choice and flexibility.
Reliability and Lifespan
Oil boilers are tough and often last 15 to 20 years. Their simpler, heavier build stands up well to years of use. However, they have more parts that need regular attention, such as the burner nozzle and fuel filter, and problems with the oil supply line or sludge in the tank can cause breakdowns.
Gas boilers usually last 10 to 15 years. They have fewer parts to wear out and no fuel storage to worry about, and spare parts are easy to find. When something goes wrong, a repair is usually quicker to arrange.
Winner: Oil boiler for lifespan, gas boiler for day to day reliability. Overall, a narrow win for oil.
Servicing and Maintenance
Both boilers should be serviced every year. A gas boiler service by a Gas Safe registered engineer usually costs £80 to £120. An oil boiler service by an OFTEC registered technician usually costs £120 to £200, because it takes longer and includes replacing the nozzle and cleaning the burner.
Oil owners also need to check the tank regularly for leaks, damage or water getting in, and keep vegetation clear around it.
Winner: Gas boiler.
Warranty
Gas boilers from leading brands often come with warranties of 7 to 12 years when fitted by an accredited installer. Oil boilers usually come with 5 to 10 years, depending on the brand and installer. In both cases, the warranty only stays valid if the boiler is registered with the manufacturer and serviced every year.
Winner: Gas boiler.
Which? and Trustpilot Ratings
Which? does not compare oil and gas as fuels. Instead it surveys owners about specific brands. Major gas boiler brands such as Vaillant, Viessmann and Worcester Bosch have a strong track record in Which? reliability and satisfaction surveys. Because far fewer homes use oil, oil brands have less survey data, though specialist makers such as Grant have a loyal following among installers and homeowners.
On Trustpilot, the bigger boiler brands generally score well, but reviews often reflect customer service as much as the boiler itself. Scores change, so check the latest ratings for the exact brand you are considering.
Winner: Gas boiler, thanks to more independent data and a wider choice of well rated brands.
Fuel Supply and Convenience
Gas flows into your home through the mains, so there is nothing to remember. With oil, you need to check the tank level, order deliveries and make sure the tanker can reach your property. Running out in a cold snap, or when delivery lorries struggle on snowy country lanes, is a real worry for rural households. A smart tank gauge, such as a Watchman sensor, can help by alerting you before levels get low.
Winner: Gas boiler.
Space and Installation Location
A gas combi boiler fits in a kitchen cupboard and needs no outside space at all. An oil boiler needs room for a tank, usually holding 1,000 to 2,500 litres, which must be placed a safe distance from the house, boundaries and drains. On the plus side, oil boilers can be installed outside in a weatherproof case, freeing up space indoors.
Winner: Gas boiler.
Safety
Gas boilers carry a risk of gas leaks and carbon monoxide poisoning if they are poorly fitted or not serviced. Oil boilers can also produce carbon monoxide, but heating oil is far less likely to cause an explosion. The main oil risks are tank leaks, which can pollute soil and water and lead to costly clean up bills, and theft of oil from the tank.
Whichever you choose, fit a carbon monoxide alarm and use a properly registered engineer.
Winner: Draw. Both are safe when installed and serviced correctly.
Environmental Impact
Heating oil produces around a third more carbon dioxide than natural gas for the same amount of heat. That makes gas the greener of the two fossil fuels, although neither is a low carbon option. Oil does have one card to play: many modern oil boilers can be converted to run on HVO, a renewable fuel made from waste vegetable oils that cuts emissions sharply.
Winner: Gas boiler, unless you convert an oil boiler to HVO.
Future Proofing
There is currently no ban on replacing an existing gas or oil boiler in an existing home in England. New build homes are moving away from fossil fuel boilers under the Future Homes Standard, and the government continues to encourage heat pumps through the Boiler Upgrade Scheme.
Earlier plans to phase out new oil boilers in off grid homes from 2026 were pushed back, so oil remains a legal choice for now. Gas has a clearer near term future simply because the network is so large, while oil has HVO as a lower carbon route.
Winner: Gas boiler, narrowly.
Can You Switch From an Oil Boiler to a Gas Boiler?
You can switch from an oil boiler to a gas boiler if your home is close enough to the mains gas network, and in Kent that means arranging a new connection with SGN, the local gas network operator. The cost of the connection is what usually decides whether switching makes sense.
A new gas connection can cost anywhere from around £1,500 to several thousand pounds, depending on how far your home is from the nearest gas main and whether the road needs digging up. Some households on lower incomes may qualify for help through SGN’s fuel poor network extension scheme, so it is worth asking.
Once gas is connected, the switch itself involves:
- Removing the old oil boiler and safely decommissioning the oil tank.
- Running a new gas supply pipe from the meter to the boiler.
- Fitting the new gas boiler, flue and controls.
- Flushing the heating system and adding a filter to protect the new boiler.
All in, switching from oil to gas often costs £4,000 to £8,000 or more, including the connection. With fuel costs per unit fairly similar, it can take many years to recover that outlay, so it pays off best when your oil tank and boiler both need replacing anyway.
Ready to Get a Free Boiler Quote From Guscott Heating?
Getting a free boiler quote from Guscott Heating is the easiest way to find out whether oil or gas is the right choice for your home, and what it will cost. We install both, so our advice is based purely on what suits your property, your budget and your plans.
One of our engineers will visit, look at your current boiler, your fuel supply and your heating system, then give you a clear, fixed price with no hidden extras. If you are off grid, we will also check your oil tank and let you know honestly whether it needs replacing.
Frequently Asked Questions
People also ask about oil usage, LPG, insurance, selling a home and boiler smells. Here are short, straight answers to the questions we hear most from customers across Kent.
How Much Heating Oil Does a Typical Home Use a Year?
A typical three or four bedroom home uses around 2,000 to 3,000 litres of heating oil a year for heating and hot water. Larger, older or poorly insulated homes can use 3,500 litres or more. A standard 1,200 litre tank would need filling two or three times a year.
Is LPG Cheaper Than Heating Oil?
LPG is usually more expensive than heating oil per unit of heat, and often the priciest of the common boiler fuels. LPG boilers are cheaper to buy and closer in design to gas boilers, but the higher fuel cost means oil is normally the better value choice for off grid homes.
Do I Need to Tell My Home Insurer About an Oil Tank?
You should tell your home insurer you have an oil tank, as a leak can cost tens of thousands of pounds to clean up. Many policies cover oil escape, but some insist the tank meets OFTEC standards and is inspected regularly. Check your policy wording for any conditions.
Does Having Oil Heating Make a House Harder to Sell?
Oil heating does not usually stop a house from selling, especially in rural areas where it is the norm. Buyers and their surveyors will ask about the age and condition of the boiler and tank, so keeping service records and installation certificates makes the sale smoother.
Should an Oil Boiler Smell?
A well serviced oil boiler should not smell inside your home. A faint smell near the flue outside when the boiler fires up can be normal. A strong oil or fume smell indoors points to a fault or leak, so switch the boiler off and call an OFTEC registered engineer.
