The UK government offers both gas and electric boilers under grants to eligible households through the Free Boiler Scheme. Now the question is, which boiler do you qualify for? Or, are you even eligible to apply? We’ll see.
We have compiled this guide to help you understand who qualifies for which type of boiler. And if not on benefits, you may still be eligible. Can’t find out without reading it through, so let’s dig deeper into this.
Two Types of Boiler Upgrade Grants (Full vs Partial Funding)
The government runs ECO4 and the Boiler Upgrade Scheme (BUS). ECO4 targets fuel poverty; it gives qualifying low-income households free heating upgrades. BUS targets decarbonisation; it pays anyone £7,500 to ditch fossil fuels for heat pumps.
ECO4 focuses on a whole-house approach. Meaning it may cover all measures required to improve the EPC rating of your house.
Gas Boilers: Still Dominating (Despite the Headlines)
Here’s what the policy papers won’t tell you upfront: 95% of UK homes on the gas grid use gas heating. That’s not changing overnight, government targets aside.
Who Gets a Free Gas Boiler Through ECO4?
You qualify if you receive certain benefits
- Income-based Jobseeker’s Allowance (JSA)
- Income-related Employment & Support Allowance (ESA)
- Income Support Allowance (ISA)
- Working Tax Credit (WTC)
- Child tax credit (CTC)
- Universal Credit (UC)
- Pension Guarantee Credit
Earn under £31,000 household income, or meet local authority flexibility criteria. Your existing boiler must be non-condensing, typically 20+ years old, or below 86.7% efficiency.
The scheme covers everything: boiler, installation, radiators, and controls. Zero upfront cost.
The Efficiency Reality
See that middle column? System efficiency accounts for generation and transmission losses. Electric boilers look perfect at home, but terrible when you trace back to the power plant.
What About BUS and Gas Boilers?
Nothing. BUS offers zero support for the gas boiler replacement scheme because gas produces 0.216 kg CO₂/kWh. The scheme wants you to choose heat pumps instead, which is why it dangles £7,500 in front of you.
But here’s the twist: the 2035 gas boiler ban got scrapped. Gas boilers remain a legitimate long-term option for existing properties. You just won’t get grant money to install one through the BUS.
Electric Boilers: The Grant Scheme Orphan
Electric boilers sit in policy purgatory. They’re not inefficient enough for ECO4 replacement grants. They’re not green enough for BUS incentives.
Why ECO4 Skips Electric Boiler Upgrades
The scheme targets electric storage heaters instead; those clunky night storage units common in off-grid properties. When ECO4 upgrades these, it installs air source heat pumps, not electric boilers.
The logic? Heat pumps operate at 300-450% efficiency by moving heat rather than generating it. Electric boilers just convert electricity to heat at 100% efficiency, which sounds great until you remember that electricity itself came from a 40% efficient power station.
The Carbon Paradox Nobody Mentions
Electric heating produces 0.519 kg CO₂/kWh compared to gas at 0.216 kg CO₂/kWh. Wait,isn’t electricity supposed to be cleaner?
Not yet. The UK grid still burns fossil fuels for 40%+ of electricity generation. Until renewables dominate completely, electric resistance heating (which includes electric boilers) produces more carbon than gas heating.
This flips the “electric is green” assumption on its head. An electric boiler might have zero emissions at your property, but the power plant feeding it doesn’t.
When Does an Electric Boiler Make Sense?
Three scenarios: You’re off-grid with no gas connection. Your property is tiny (1-2 bedroom flat) with minimal heating demand. You’re installing solar panels that generate surplus electricity.
Otherwise? The running costs destroy any appeal.
The Cost Structure That Grant Schemes Ignore
Want to know why gas remains dominant? Follow the money.
Fuel Costs (per kWh):
- Electricity: 27p
- Gas: 7p
That 4:1 price ratio swamps efficiency differences. Even though an electric boiler wastes almost nothing and a gas boiler loses 5-10% through the flue, gas still costs half as much to run annually.
For ECO4 recipients, this matters enormously. A free condensing gas boiler saves them £100+ yearly in fuel costs compared to electric alternatives. Over a 15-year lifespan, that’s £1,500+ in reduced heating bills, meaningful for fuel-poor households.
BUS recipients face different math. If you’re choosing between a £7,500-discounted heat pump and a self-funded gas boiler, the heat pump’s £734-£938 annual running costs undercut gas at £1,200-£1,800.
Maintenance: The Hidden Cost Difference
Gas boilers require annual Gas Safe servicing at £80-£120. This isn’t optional; your warranty and home insurance depend on it. Plus, there’s a carbon monoxide risk if components fail.
Electric boilers need servicing every 1-2 years at £70-£110. No combustion means no CO risk and fewer moving parts to break.
Grant schemes don’t factor this into eligibility, but over 15 years, you’re looking at £1,200-£1,800 in gas boiler maintenance versus £525-£825 for electric. That’s real money the grants don’t compensate for.
Property Type Determines Your Options
Gas Boilers Excel When:
- Property is on the gas grid
- Home has 3+ bedrooms
- Multiple bathrooms need simultaneous hot water
- High heating demand (150+ m² floor area)
Electric Boilers Work When:
- Off-grid rural location
- Small flat or 1-2 bedroom property
- Low simultaneous hot water demand
- Supplementing with solar PV
ECO4 doesn’t care about property size; if you qualify and need a replacement, you get what suits your heating load. BUS requires proper insulation before approving heat pump grants, which effectively excludes poorly-insulated larger properties until you upgrade the building fabric first.
EPC Requirements: The Eligibility Gatekeeper
Both schemes demand valid Energy Performance Certificates, but they use them differently.
ECO4: Targets E, F, G ratings (potentially D later). Your poor EPC proves you need help.
BUS: Requires a valid EPC but no minimum rating. However, if your EPC recommends loft or cavity insulation, you must complete that work before claiming grants.
See the difference? ECO4 treats poor energy performance as a qualification criterion. BUS treats it as a prerequisite problem you must fix first.
This explains why some homeowners get rejected despite wanting heat pumps; their property isn’t thermally ready.
The Application Strategy Nobody Explains
If you’re low-income on benefits: Apply for ECO4. Don’t overthink it. You’ll get a free gas boiler replacement if you’re on-grid and your current system qualifies. If you’re off-grid with electric storage heaters, you’ll likely get an air source heat pump instead.
If you’re middle-income, replacing a gas boiler: Consider BUS for heat pumps. The £7,500 grant plus lower running costs (£734-£938 vs £1,200-£1,800 annually) makes financial sense if your property is well-insulated.
If you have an electric boiler already, neither scheme helps you. ECO4 doesn’t upgrade electric boilers. BUS doesn’t fund replacements of electric systems with more electric systems.
Can you combine both schemes? No. One heating system, one grant. Choose the pathway that matches your eligibility and property characteristics.
Final Thoughts
The “best” boiler depends entirely on which grant you qualify for. Not on theoretical efficiency. Not on environmental virtue signalling. On cold, hard eligibility criteria.
Fuel-poor households on the gas grid benefit most from ECO4’s free condensing gas replacement. It delivers immediate bill reduction and improved comfort with zero upfront cost.
Homeowners planning 15+ year heating strategies should investigate BUS heat pumps. The running cost savings and future-proofing against potential carbon taxation outweigh the higher installation complexity.
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