Share
🔍 Understanding Boiler Efficiency Ratings (ErP A–G Explained)
When it comes to choosing a new boiler or assessing the one you have, efficiency ratings are a crucial factor to understand. A more efficient boiler saves you money on energy bills and reduces your carbon footprint — but what do those ErP ratings (like A-rated or G-rated) really mean?
In this guide, we’ll break down:
- What ErP ratings are
- How they affect your heating bills
- What to look for when choosing a new boiler
🧾 What Is ErP?
ErP stands for Energy-related Products Directive, a European Union regulation introduced in 2015 to help consumers compare energy efficiency across heating and hot water products. It's similar to energy labels you see on fridges and washing machines.
The ErP label uses a letter grading system (A+++ to G) and colour codes (green to red) to show how efficient an appliance is.
🔠 ErP Boiler Efficiency Ratings Explained
| Rating | Efficiency (%) | Label Colour | Meaning |
|---|---|---|---|
| A+++ | 90%+ | Dark Green | Ultra-efficient (typically heat pumps) |
| A+ to A | 89–90% | Light Green | Most modern condensing boilers |
| B–C | 80–88% | Yellow/Light Orange | Mid-efficiency; may be older models |
| D–G | Below 80% | Orange to Red | Poor efficiency; costly to run |
Most modern gas combi boilers sold today are A-rated, offering around 90% efficiency or more. Older, non-condensing boilers (usually 15+ years old) often fall into the D–G range, wasting a lot of energy.
💷 Why Boiler Efficiency Ratings Matter
An inefficient boiler doesn't just use more gas — it wastes heat that could be warming your home.
Here’s why that matters:
- 🔥 Lower efficiency = higher bills
A G-rated boiler could be wasting up to 30p of every £1 spent on heating. - 🌍 More carbon emissions
A-rated boilers are better for the environment. - 🏠 Less comfort
Older boilers can struggle to maintain consistent temperatures.
🛠️ ErP Ratings vs SEDBUK (What's the Difference?)
Before ErP, the UK used the SEDBUK rating (Seasonal Efficiency of Domestic Boilers in the UK), shown as a percentage.
| SEDBUK Rating | ErP Equivalent |
|---|---|
| 90%+ | A |
| 80–89% | B–C |
| < 80% | D–G |
Both systems aim to measure seasonal efficiency, but ErP is now the standard across the UK and Europe for domestic boilers and heating products.
🔁 Should I Replace My Old Boiler?
If your current boiler is more than 10–15 years old, it might be D-rated or worse. Upgrading to an A-rated condensing boiler could:
- Cut your gas bills by up to £300 per year
- Reduce the risk of breakdowns
- Make your home more attractive to buyers
🛑 Warning signs of an inefficient boiler:
- Takes ages to heat up
- Constantly losing pressure
- Frequently needs repairs
- High gas bills despite moderate usage
✅ What to Look for in a High-Efficiency Boiler
- ✔️ ErP A-rated (at least 90% efficiency)
- ✔️ Modulating burner for smart heating control
- ✔️ Built-in smart thermostat compatibility
- ✔️ Warranty of 7+ years
- ✔️ Good manufacturer support
Some of the most efficient models in 2025 include options from Worcester Bosch, Vaillant, Ideal, and Viessmann.
📦 Final Thoughts: Efficiency = Long-Term Savings
Understanding ErP ratings gives you the power to make informed decisions. Whether you're looking to replace an old system or just want to learn more, remember: a higher rating means more savings, more comfort, and lower environmental impact.
🧰 Need Help Choosing a New Boiler?
At Gas-Go Heating, we supply and install A-rated energy-efficient boilers across Hampshire.
We’ll help you find the right system for your home — and start saving from day one.
📞 Contact us today on 02393 782351