Boiler Replacement Savings Calculator
Annual energy savings from new efficient boiler.
Calculate annual savings and payback from replacing an old inefficient boiler. Enter annual gas bill and efficiency gain for an instant result.
What this tool does
Enter annual bill, efficiency gain, new boiler cost. The tool shows annual savings and payback.
Enter Values
Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
1,200 annual gas × 20% efficiency gain = 240/year savings. 3,000 new boiler: 12.5 year payback. Old G-rated boilers vs new A-rated often 20-30% efficiency improvement. Payback 8-12 years typical — long tail compared to other upgrades.
Run it with sensible defaults
Using current annual gas bill of 1,200, efficiency gain of 20%, new boiler cost of 3,000, the calculation works out to 12.5 years. Nudge the inputs toward your own situation and the output recalculates instantly. The defaults are meant as a starting point, not a recommendation.
The levers in this calculation
The inputs — Current Annual Gas Bill, Efficiency Gain, and New Boiler Cost (installed) — do not pull with equal force. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.
How the math works
Simple payback calculation. The working is transparent — you can verify every step yourself in the formula section below. No black box, no opaque "proprietary model".
Why run the numbers before the purchase
Big purchases reward slow thinking. The calculation here is fast; the decision it informs isn't. Running this before you shop is the cheapest way to avoid the "seemed fine in the showroom" trap.
What this doesn't capture
Purchase decisions rarely come down to payback alone. Reliability, time saved, enjoyment, and alternatives outside the calculation all matter. The figure gives you the money side cleanly so you can weigh it against everything else honestly.
Related calculations worth running
Plans get firmer when you triangulate. Alongside this one, the heat pump vs boiler break even, the ev vs petrol running cost calculator, and the mattress replacement calculator tend to come up in the same conversations. Running two or three together exposes inconsistencies in any single assumption — which is usually where the useful insight lives.
Boiler replacement savings produces annual and payback figures based on the inputs provided.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
Simple payback calculation.
References
Frequently Asked Questions
Replace older?
Combi vs system?
Heat pump alternative?
Warranty?
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