03/06/2016
For many homes across the UK, particularly those in more remote locales, the familiar sight of an oil tank in the garden signifies their primary source of heating. While gas boilers dominate the market, a significant 5% of the UK population still relies on oil to warm their residences. If you're among them and contemplating an upgrade, the prospect of replacing your existing oil boiler with a more modern, efficient system, such as a gas combi boiler, presents a compelling opportunity to not only enhance your home's comfort but also significantly reduce those ever-present energy bills.
This comprehensive guide will delve into the intricacies of oil boilers, explore the compelling reasons to consider a switch to a gas combi boiler, detail the costs and processes involved in such a conversion, and provide an overview of other viable heating alternatives. Our aim is to equip you with all the necessary information to make an informed decision for your home's heating future.
- Understanding Your Current Oil Heating System
- Why Consider a Change from Oil Heating?
- The Case for a Gas Combi Boiler Conversion
- Understanding the Costs: Oil to Gas Combi Conversion
- What to Expect During an Oil to Gas Combi Conversion
- Exploring Other Heating Alternatives to Oil
- Choosing the Right Gas Combi Boiler for Your Home
- Finding the Best Installer for Your Conversion
- Frequently Asked Questions (FAQs)
- Conclusion
Understanding Your Current Oil Heating System
What is an Oil Boiler?
Much like their gas counterparts, oil boilers are designed to provide central heating and domestic hot water. However, instead of drawing natural gas from the mains supply, they rely on heating oil. This makes them a popular, often essential, choice for properties not connected to the national gas grid. An oil tank, typically stored on-site in your garden or a surrounding area, acts as the fuel reservoir, with the boiler drawing its supply from it. The primary difference from mains gas is the need to periodically arrange for a supplier to top up your tank, requiring you to monitor fuel levels to avoid running out.
Types of Oil Boilers
Oil boilers come in various configurations, each suited to different property types and hot water demands:
Regular Oil Boilers
These are the oldest type of boiler and are commonly found in larger, traditional homes. A regular oil boiler system typically involves a cold water cistern, usually located in the loft, which feeds water to the boiler. The boiler then heats this water, which is subsequently stored in a separate hot water cylinder. While excellent for larger homes with multiple bathrooms, the significant space requirement for the oil tank, cistern, and cylinder can be a drawback. Furthermore, once the stored hot water is depleted, you must wait for the cylinder to refill and reheat before more hot water becomes available.
Oil System Boilers
An evolution from regular boilers, oil system boilers draw their water supply directly from the mains, eliminating the need for a cold water F & E (feed and expansion) tank in the loft. The heated water is still stored in a hot water cylinder, similar to a regular boiler setup. This offers a slightly more streamlined installation than a regular boiler, freeing up some loft space, but still requires a dedicated hot water cylinder.
Oil Combi Boilers
Oil combi (combination) boilers are designed to provide central heating and hot water on demand, much like standard gas combi boilers. The key distinction is their fuel source – burning oil instead of natural gas. Aside from the external oil tank, no additional cylinders or tanks are required within the home, making them a space-saving solution. Oil combi boilers are often ideal for smaller homes with less demanding hot water requirements, as they may struggle to meet the simultaneous hot water needs of larger properties with multiple occupants.
Why Consider a Change from Oil Heating?
While oil boilers serve their purpose, several compelling reasons might prompt you to consider an upgrade, particularly to a gas combi system:
The Drive for Efficiency and Savings
Modern gas boilers, especially condensing combi models, boast impressive levels of efficiency. Natural gas is generally more affordable per unit than heating oil, a primary reason why a substantial 78% of UK homes rely on gas for heating. Switching could lead to a noticeable decrease in your energy bills over time. Older oil boilers can be significantly less efficient, meaning a considerable portion of your fuel cost is wasted.
Reclaiming Valuable Space
One of the most immediate and tangible benefits of converting to a gas combi boiler is the significant space-saving. With a gas combi, there's no need for an external oil storage tank, nor internal hot water cylinders or cold water cisterns. This frees up garden space, airing cupboards, and loft areas, which can then be repurposed for storage or other uses – a considerable advantage, especially in smaller properties or flats where space is at a premium.
Convenience and Supply
Unlike oil, which requires you to monitor levels and arrange for periodic deliveries, natural gas is supplied directly to your home via the gas grid. This offers unparalleled convenience, eliminating the risk of running out of fuel and the hassle of managing deliveries. Manufacturers also continuously invest in more efficient and reliable technology for gas boilers due to their widespread popularity.
The Case for a Gas Combi Boiler Conversion
How Gas Combi Boilers Work
A gas combi boiler works by taking its water supply directly from the mains. When you turn on a hot tap or the central heating, the boiler fires up, instantly heating the water as it flows through the unit. This means hot water is provided on-demand, without the need for a storage cylinder.
Key Benefits of Switching to Gas Combi
- Instant Hot Water: No waiting for a tank to heat up.
- Space-Saving: As mentioned, no hot water cylinder or cold water tank needed.
- Energy Efficiency: Modern condensing combi boilers are highly efficient, converting more fuel into usable heat.
- Lower Running Costs: Natural gas is typically cheaper than oil.
- Convenience: Continuous supply from the gas grid.
Is a Gas Combi Conversion Right for Your Home?
For most small to medium-sized properties in the UK, a gas combi boiler is an excellent choice. It’s highly efficient, saves space, and provides hot water whenever you need it. However, if your household has a very high demand for hot water – perhaps with multiple showers running simultaneously, as is common in larger families – a standard combi boiler might struggle to maintain adequate pressure and temperature. In such cases, a newer conventional or system boiler (still fueled by gas, if connected to the grid) might be a more suitable option, as they utilise hot water storage cylinders to cope with peak demand. It's always advisable to assess your specific hot water usage before committing to a combi.
Understanding the Costs: Oil to Gas Combi Conversion
Converting from an oil boiler to a gas combi boiler is a more involved process than a like-for-like boiler replacement, and thus incurs additional costs. The overall conversion cost will depend on various factors, including your property's existing setup and its proximity to the gas grid.
Typical Combi Boiler Installation Costs
For a small to medium-sized property, a standard gas combi boiler replacement (i.e., replacing an old combi with a new combi) typically ranges from £1,800 to £2,200. However, an oil to gas combi conversion involves significant extra work.
Additional Costs for a Combi Conversion
When converting from an oil system to a gas combi, you'll need to factor in the following:
Removing the Hot Water Tank
One of the main benefits of a combi boiler is the elimination of the hot water cylinder. The removal of this tank, along with the associated pipework, typically costs between £100 and £150.
Removing the Water Feeder Tank
If you have an older regular oil boiler, you'll also have a cold water feeder tank (often in the loft) that will need to be removed. This procedure usually adds £200 to £300 to the total cost.
Connecting to the Gas Grid
This is potentially the most significant additional cost. If your property is not currently connected to the gas grid, you will need to arrange for a connection. The cost for this varies widely based on your proximity to the nearest gas main. If you're in a very remote location, this could be prohibitively expensive, potentially running into thousands of pounds. It's crucial to get a quote from your local gas network operator for this before planning the boiler conversion.
Special Considerations for Back Boilers
If your existing oil boiler is a 'back boiler' (installed behind a fireplace), the decommissioning and removal process is more complex and will incur higher costs due to the specialised procedure required to ensure safety.
Factors Influencing the Total Price
Beyond the core conversion tasks, several other elements can affect the final installation price:
| Factor | Impact on Cost |
|---|---|
| Boiler Relocation | Moving the new combi boiler to a different location (e.g., from the garage to a kitchen cupboard) requires rerouting pipework and drilling a new flue hole, increasing labour. |
| Gas Run Upgrade | The existing gas supply pipework may need upgrading to meet current Gas Safe regulations and handle the combi boiler's demand. |
| Heating Controls Upgrade | Modern combi boilers often benefit from new, more advanced heating controls (e.g., smart thermostats), which add to the cost. |
| System Filters | Installation of a magnetic system filter (highly advised to protect the boiler from sludge) and a limescale filter (advised for hard water areas) adds to the cost but extends boiler lifespan. |
| TRVs (Thermostatic Radiator Valves) | Adding TRVs to radiators allows for individual room temperature control, improving efficiency but increasing installation time and cost. |
| Boiler Warranty Length | Boilers with longer warranties (e.g., 10 years) often have a higher upfront cost but offer greater peace of mind and potentially longer lifespan. |
| Complexity of Pipework | Extensive rerouting of gas, water, and central heating pipework will increase labour costs. |
Overall, assuming a straightforward oil to gas combi conversion (excluding potentially very high gas grid connection costs for remote properties), you should anticipate paying in the region of £2,700 to £3,000.
What to Expect During an Oil to Gas Combi Conversion
The Conversion Process Explained
A Gas Safe registered heating engineer will carry out the conversion, which involves several key steps:
- Initial Assessment: The engineer will first assess your current oil heating system, pipework, and the suitability of your property for a gas connection.
- Gas Supply Connection: If not already connected, the gas network operator will install a new gas supply line to your property. This work is separate from the boiler installation itself.
- Decommissioning Old System: The oil boiler will be safely decommissioned, and the oil tank emptied and removed. The hot water cylinder and cold water feeder tank will also be removed, freeing up valuable space.
- New Boiler Location & Flue: If the new combi boiler is to be installed in a different location (e.g., a kitchen cupboard), a new core hole will be drilled for the flue, which safely expels combustion gases outside.
- Gas Pipework Upgrade: The existing gas supply pipework within your home may need to be upgraded to meet current standards and ensure it can adequately supply the new combi boiler.
- Water Pipework Adjustment: The hot and cold water pipework will be rerouted and adapted to connect directly to the combi boiler, as there will no longer be a need for separate storage tanks.
- Heating System Flush: The existing central heating system (radiators and pipes) will be thoroughly flushed (e.g., a power flush) to remove any sludge or debris that could impair the new boiler's performance and efficiency.
- Installation of Filters: A magnetic system filter is typically installed to protect the new boiler from future sludge build-up, and a limescale filter may be added in hard water areas.
- New Heating Controls: New heating controls, which can include a room thermostat and programmer, will be installed and configured for optimal operation with the combi boiler. TRVs (Thermostatic Radiator Valves) may also be added to radiators if not already present.
- Testing and Commissioning: The new gas combi boiler will be thoroughly tested and commissioned to ensure it is operating safely and efficiently, and the engineer will provide you with all necessary documentation.
Exploring Other Heating Alternatives to Oil
While a gas combi boiler is a popular and often economical choice, it's worth understanding the full spectrum of alternatives if you're looking to move away from oil heating. Each has its own set of advantages and disadvantages:
| System Type | Fuel Type | Pros | Cons | Typical Suitability |
|---|---|---|---|---|
| Gas Combi Boiler | Natural Gas | High efficiency, instant hot water, no tanks, lower running costs than oil, convenient. | Requires gas grid connection (can be costly if remote), may struggle with very high simultaneous hot water demand. | Small to medium homes with access to gas grid. |
| Electric Boiler | Electricity | Cheaper installation (no flue/gas line), no fossil fuels (if renewable electricity), no tank needed. | Very expensive to run due to high electricity costs, not suited for large homes/high demand. | Small flats, properties with low heating/hot water demand, off-grid locations where gas is not an option. |
| Heat Pump (Air/Ground Source) | Electricity (to run pump) | Highly efficient, very low carbon emissions, extracts heat from air/ground. | High initial investment, lower heat output than boilers (best with underfloor heating/large radiators), can struggle in very cold weather, requires good insulation. | Well-insulated, larger homes, new builds, properties with underfloor heating. |
| Hybrid System | Gas/Oil Boiler + Heat Pump/Solar Thermal | Combines efficiencies, adaptable to seasons, lower overall energy consumption. | More complex installation, higher initial cost than a single system. | Homes seeking a balance of efficiency and reliability, or phasing out fossil fuels gradually. |
| LPG Boiler | Liquefied Petroleum Gas | Similar operation to gas/oil boilers, often cheaper to purchase than oil boilers, no gas grid needed. | Requires a storage tank (like oil), LPG fuel is more expensive than mains natural gas. | Off-grid properties where natural gas connection is unfeasible, seeking a gas-like experience. |
| Biomass Boiler | Wood Pellets, Chips, Logs | Sustainable fuel source, low carbon emissions (if sustainably sourced), RHI payments (check current schemes). | High initial investment (£4,000-£8,000+), requires significant space for boiler and fuel storage, regular fuel deliveries and loading. | Rural properties with ample space and access to biomass fuel, environmental focus. |
Choosing the Right Gas Combi Boiler for Your Home
If you decide a gas combi boiler is the way forward, several factors will influence your choice of model:
- kW Output: This indicates the boiler's power. It must be sufficient to meet your home's heating and hot water demands. A qualified installer will help calculate the correct output for your property size and number of bathrooms.
- Physical Dimensions: If you plan to install the boiler in a tight space, such as a standard kitchen cupboard, you'll need a compact model. Many manufacturers offer slimline combi boilers designed for this purpose.
- Warranty: This is a crucial indicator of a manufacturer's confidence in their product. We strongly recommend choosing a boiler with a minimum 5-year warranty, with 10-year warranties being preferable if your budget allows. While a boiler's cost typically makes up about 40% of the total installation price, skimping on warranty to save a small amount upfront can lead to costly repairs down the line.
Finding the Best Installer for Your Conversion
The quality of your boiler installation is just as important as the boiler itself. There are thousands of installers across the UK, ranging from small local businesses to large national companies. Prices for the same job can vary significantly.
It's always wise to:
- Get Multiple Quotes: Obtain at least three quotes from different installers to compare prices and services.
- Check Credentials: Ensure any installer you consider is Gas Safe registered for gas boiler installations. This is a legal requirement and ensures they are qualified and competent to work safely with gas.
- Read Reviews: Check online reviews and testimonials (e.g., on Trustpilot) to gauge other customers' experiences.
Online boiler installers have emerged as a popular option. Companies like Heatable, for instance, use automated online quote systems that can reduce overheads associated with traditional firms (like phone representatives or on-site salespeople). This often means their prices can be highly competitive, sometimes on par with local installers, while offering the convenience of fixed online quotes and next-day installation.
Frequently Asked Questions (FAQs)
Can I change from an oil boiler to a gas combi boiler?
Yes, absolutely. It is a common and often beneficial upgrade. However, it's important to understand that such a conversion is more involved than a simple like-for-like boiler swap. It typically entails substantial changes to your central heating infrastructure, including:
- Potentially connecting your property to the natural gas grid.
- Rerouting gas, water, and central heating pipework.
- Removing the old hot water cylinder and cold water storage tanks.
- Installing the new combi boiler, potentially in a new, more convenient location.
- Peripheral work required to support these tasks, such as system flushing and controls upgrades.
Due to this increased workload, you will pay more for a full conversion than for a straight replacement of the same boiler type.
Is it worth changing to a gas combi boiler?
For most small-to-medium-sized homes in the UK, especially those with access to the gas grid, changing to a gas combi boiler is generally a worthy investment. The benefits include significant space savings (no hot water tanks), instant hot water on demand, increased energy efficiency, and typically lower running costs compared to oil. However, if you have a very busy household that frequently uses multiple showers or hot water taps simultaneously, a standard combi boiler might struggle to meet the demand. In such specific scenarios, a new regular or system boiler might be a better fit, offering high hot water output from a storage cylinder.
How long do modern combi boilers last?
You can generally expect a modern gas combi boiler to last around 15 years, provided it receives annual servicing and appropriate preventative maintenance, such as protecting against sludge and limescale build-up. The lifespan can vary between models and brands. A good indicator of a manufacturer's confidence in their product's longevity is the length of its warranty. Boilers with a 10-year warranty are typically built to a higher standard and are expected to last longer than those with a meagre 2-year warranty. Investing in a boiler with a substantial warranty can provide peace of mind and save you from unexpected costs down the line.
Conclusion
Deciding whether to replace your oil boiler with a gas combi boiler is a significant decision for any homeowner. The transition offers compelling benefits, including improved energy efficiency, considerable space-saving advantages, and often lower running costs due to the affordability and convenience of natural gas. While the initial conversion cost can be higher than a simple boiler swap, the long-term savings and enhanced comfort often make it a sound investment.
However, it's crucial to assess your home's specific needs, particularly hot water demand, and consider your property's connection to the gas grid. Explore all alternatives, from heat pumps to LPG, to ensure you select the heating solution that is truly best suited for your household and lifestyle. By carefully researching, obtaining multiple quotes from Gas Safe registered engineers, and understanding the process, you can confidently upgrade your heating system for a warmer, more efficient, and more convenient future.
If you want to read more articles similar to Switching from Oil to a Gas Combi Boiler in the UK, you can visit the Automotive category.