If your EPC recommends “Replace boiler with a new condensing boiler” or flags your heating system as inefficient, it’s natural to ask: will a new boiler actually improve my EPC rating – and by how much?
The short answer: yes, it often can, especially if you’re replacing a very old non-condensing boiler. But a new boiler is rarely the first step, and it works best when combined with insulation and better controls.
This guide covers:
- How EPCs treat boilers and heating systems
- How much EPC improvement you can realistically expect
- When a boiler upgrade makes sense vs when to prioritise other measures
For a full cost breakdown, read New Boiler Cost UK (2025 Guide). Here, we focus on EPC impact.
How EPCs assess your boiler and heating system
The EPC model looks at:
- The type of boiler (combi, system, regular)
- Whether it’s condensing or non-condensing
- The fuel it uses (mains gas, LPG, oil, etc.)
- The efficiency rating (often from manufacturer data or standard tables)
- The presence and quality of heating controls (thermostats, programmers, TRVs)
Together, these factors determine:
- How much energy is needed to heat your home to a standard level
- How much of that energy ends up as useful heat vs being lost in flue gases
Upgrading a boiler essentially improves the efficiency component – more of the energy you buy is turned into usable heat.
How much can a new boiler improve your EPC rating?
There is no one-size-fits-all answer, but typical patterns include:
- Replacing a non-condensing G-rated boiler with a modern A-rated condensing boiler can add several SAP points – sometimes enough to move a borderline property up a band.
- Upgrading from an already condensing but older boiler to a slightly more efficient model will have smaller EPC impact, though you may still see bill savings.
The biggest EPC gains generally occur when:
- Your current boiler is very old and inefficient.
- Your property already has reasonable insulation (loft/walls) so heating accounts for a large share of your energy use.
You can check how much your heating system is holding you back by reviewing the recommendations and heat demand sections on your EPC. Start by looking up your property via our EPC checker.
When is a new boiler worth considering for EPC improvement?
1. Your boiler is at end-of-life anyway
If your boiler is already:
- Breaking down frequently,
- Expensive to repair, or
- Nearing the end of its expected lifespan,
then upgrading to an efficient model gives you:
- Reduced running costs and improved reliability, and
- A better EPC rating as a side benefit.
2. You’re borderline on an EPC band
If you’re just a few points below a target band (for example, D 66 aiming for C 69):
- Loft/wall insulation and controls may close most of the gap.
- A boiler upgrade can then provide the extra push into the higher band.
Use How to Improve EPC from D to C and Cheapest Ways to Improve Your EPC Rating to decide whether a boiler or another fabric measure is the better “finisher” for your situation.
3. You’re a landlord planning ahead for tighter standards
For landlords, a new boiler can be part of a long-term strategy to reach or maintain minimum EPC standards:
- Current rules focus on avoiding F and G bands.
- Future proposals have pointed towards band C for rentals.
Upgrading to an efficient boiler can help protect you against future tightening of rules – but only if combined with fabric measures. For a full compliance view, see:
When other measures should come first
Even if your boiler is old, it isn’t always the first thing to change.
Priority often goes to:
- Loft insulation improvements – see Does Loft Insulation Improve Your EPC?
- Cavity wall insulation where suitable
- Basic draught proofing and floor insulation
- Heating controls (thermostats, programmers, TRVs)
These can be cheaper per EPC point gained than a boiler replacement. Once you’ve addressed them, a boiler upgrade can then maximise the benefit of your reduced heat demand.
Boiler types and EPC impact
Gas combi vs system vs regular boilers
From an EPC perspective:
- What matters most is the efficiency rating, not just the boiler type.
- A modern A-rated combi or system boiler will generally score better than an old G-rated boiler of any type.
Other considerations (hot water comfort, cylinder vs combi, system complexity) should also inform your choice but are not directly EPC-specific.
Electric boilers and direct electric heating
Electric boilers can simplify pipework, but in the EPC model, electric resistance heating is treated as less efficient from a primary energy and carbon perspective than gas – even if the device itself is “100% efficient” at point of use.
That means switching a gas boiler to a straightforward electric boiler can hurt your EPC unless you pair it with exceptionally good insulation or on-site generation (like solar PV).
Heat pumps vs boilers
Heat pumps are treated very favourably in EPC calculations because they deliver multiple units of heat for each unit of electricity consumed.
- In some homes, switching from a gas boiler to a well-designed heat pump can significantly boost EPC scores.
- However, they work best in well-insulated properties with suitable emitters (radiators/underfloor).
For a detailed comparison of running costs and suitability, see Boiler vs Heat Pump: Cost Comparison and Air Source Heat Pump Costs UK.
How much does a new boiler cost?
Costs depend on:
- Property size and heat requirement
- Boiler type and brand
- Installation complexity (e.g. relocating boiler, flue changes, system cleaning)
Our full breakdown is in New Boiler Cost UK (2025 Guide), but as a broad range:
- Combi boiler replacement: often £2,000–£3,000+ including installation
- System or regular boiler upgrades: often £2,500–£4,000+ depending on cylinder and system changes
Because these are ballpark figures, always get fixed quotes from reputable installers before making a decision.
Grants and funding for boiler upgrades
Grants for traditional gas boilers are more limited than for low-carbon options, but you may still benefit from:
- Boiler upgrade or replacement schemes targeting inefficiency (through some local programmes).
- Wider home energy grants that include heating upgrades as part of a package.
If you’re more interested in switching to a heat pump, the Boiler Upgrade Scheme may help with upfront costs. For an overview of the funding landscape, see Home Energy Grants UK 2025: Complete Guide to Funding (/insights/home-energy-grants-uk) and Boiler Grants UK 2025.
How a new boiler fits into your overall EPC plan
Think of a new boiler as one element in a wider improvement strategy:
- If you’re going from E to D, focus first on loft and wall insulation, then consider the boiler – see How to Improve EPC from E to D.
- If you’re going from D to C, the boiler may be a key part of the final push, especially in homes already well insulated – see How to Improve EPC from D to C.
- For Victorian or solid-walled homes, make sure the fabric is addressed before sizing new heating – see How to Improve EPC on Victorian House.
Use your property report from our EPC checker to see where “replace boiler” sits in the list of recommended measures and compare it against cheaper EPC wins.
FAQs
Will a new boiler on its own move me up an EPC band?
Sometimes – especially if your current boiler is very old and you’re close to the next band. But in many cases, you’ll need boiler + insulation or boiler + controls to see a full-band improvement.
Do I need to change radiators when I replace my boiler?
Not always. Many boiler replacements can reuse existing radiators, though your installer may recommend system cleaning or partial radiator upgrades for best performance. Heat pumps, by contrast, more often require emitter changes due to lower flow temperatures.
Should I pick a boiler or a heat pump for a better EPC?
From an EPC perspective, a well-designed heat pump can often score better than a gas boiler – but only if your property is ready and the system is correctly specified. A high-efficiency boiler may still be the more practical step in many homes today. Compare both using Boiler vs Heat Pump: Cost Comparison and your EPC recommendations.
What should I do next?
- Use the EPC checker to view your current rating and recommendations.
- Read New Boiler Cost UK (2025 Guide) for pricing context.
- Consider whether loft/wall insulation and controls should come before or alongside a boiler upgrade.
- Once you’ve made improvements, book a new EPC assessment to see your updated rating – and then plan the next steps using 27 Ways to Improve Your EPC Rating.