How This Tool Works
📋 Purpose
This tool is designed to cut through the complexity of a boiler upgrade. It moves beyond simple efficiency ratings to provide a clear, personalised financial forecast, showing you exactly when a new boiler starts paying for itself and how much it could save you in the long run.
⚙️ How It Works
- 1Enter details about your current boiler, including its type and age, along with your annual heating bill.
- 2Select the type of new boiler you are considering and specify your desired analysis timeframe.
- 3Receive an instant, detailed financial breakdown, including annual savings, payback period, and total net benefit.
Property Location
Enter your postcode to get regional cost estimates
Required to fetch regional install cost benchmarks. The Calculate button stays disabled until a valid postcode is entered.
Current Boiler
Tell us about your existing heating system
Energy Usage
Provide your annual usage or monthly bill amount
Check your energy bill or annual statement for this figure
Upgrade Details
Specify the boiler you're considering
If left blank, we'll use regional benchmark costs
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Complete Guide: Planning a Boiler Upgrade ROI
Understand payback, long-term savings, and the assumptions that most affect upgrade decisions.
📅 Last updated: 2026-04-01
Quick Tips
Jump-start your understanding with these essential tips
Your annual heating spend has the biggest impact on estimated savings. Start with a realistic 12-month figure from statements, then test a higher and lower case to understand upside and downside.
If you have multiple quotes, run all of them. Payback can shift materially with install cost differences, so scenario testing is essential before committing to a contractor.
If you are considering an air or ground source heat pump, the Boiler Upgrade Scheme (BUS) grant can reduce the upfront cost by up to £7,500 — significantly shortening payback.
A 15-year-old combi boiler runs far less efficiently than its rated output. The tool adjusts for age-related degradation so your savings estimate reflects reality, not just nameplate specs.
Step-by-Step Guide
Follow these steps to get the most from this tool
Enter your current boiler type, age band, and annual heating spend. These inputs establish your present operating cost and expected efficiency baseline.
💡 Pro Tips:
- •Use a full-year energy total to reduce seasonal bias.
- •Match age band as closely as possible for realistic benchmarks.
Select the target boiler type and installation cost assumptions. The model combines expected efficiency gain with installation and maintenance profiles to estimate net financial impact.
💡 Pro Tips:
- •If you have a formal quote, use it instead of benchmark install cost.
- •Include maintenance assumptions, not just fuel savings.
Review annual savings, payback period, and cumulative net benefit across your selected horizon. Use the sensitivity view to check how robust your decision is to fuel price and efficiency uncertainty.
💡 Pro Tips:
- •Decisions are strongest when payback remains acceptable in downside scenarios.
- •Export outputs to compare with alternative upgrades like insulation or heat pumps.
Advanced Topics
Deep dives for advanced users
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Frequently Asked Questions
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