Terms of Service & Engineering Disclaimer
Last Updated: January 2026
By accessing BoilerSizeCalculator.com you agree to the terms set out below. If you do not accept them, please do not use the calculators, charts, or reference tables published on this site.
1. Informational & Estimation Tool Only
The calculations, outputs, and recommendations provided by BoilerSizeCalculator.com are generated for planning, preliminary estimation, and educational comparison purposes. They do not constitute an official on-site structural or Gas Safe / licensed HVAC engineering survey.
2. Professional Verification Required
Prior to purchasing heating equipment, altering gas pipework, or installing boilers, you must obtain a formal on-site heat loss survey conducted by a certified heating engineer (e.g., Gas Safe registered in the UK, OFTEC for oil, EPA/NATE licensed in the US).
Gas work in the United Kingdom is legally restricted to Gas Safe registered engineers under the Gas Safety (Installation and Use) Regulations 1998. Nothing on this site authorises you to carry out notifiable work yourself.
3. Accuracy, Standards & Limitations
Our sizing engines implement published methodologies including BS EN 12831, CIBSE Guide A, ACCA Manual J, and BS 5449 fabric heat-loss principles. Because we cannot inspect your property, results depend entirely on the inputs you supply — floor area, glazing ratio, insulation standard, design temperatures, simultaneous hot water demand, and system pressure. Small input errors compound, so treat every output as a starting range rather than a specification.
Building regulations, efficiency minimums, and appliance availability differ by country and are periodically revised. We update our reference data on a best-effort basis but make no guarantee that any figure reflects the current regulation in your jurisdiction.
4. No Warranty
This site and its tools are provided "as is" and "as available", without warranty of any kind, whether express or implied, including but not limited to merchantability, fitness for a particular purpose, accuracy, or non-infringement. We do not warrant uninterrupted or error-free operation.
5. Limitation of Liability
To the fullest extent permitted by law, BoilerSizeCalculator.com and its contributors accept no liability for any direct, indirect, incidental, consequential, or economic loss — including undersized or oversized appliance purchases, installation rework, fuel costs, property damage, or loss of comfort — arising from reliance on the information or calculations published here. Nothing in these terms excludes liability that cannot lawfully be excluded, including liability for death or personal injury caused by negligence.
6. Acceptable Use
You may use this site for lawful personal and professional purposes. You must not attempt to disrupt the service, bypass rate limits, scrape our datasets at volume for republication, reverse engineer our calculation logic for a competing commercial product, or misrepresent our outputs as a certified engineering report issued on your behalf.
7. Intellectual Property & Embeds
You are permitted to embed our calculator widget on third-party websites provided the attribution link to BoilerSizeCalculator.com remains intact and functional.
All original text, benchmark tables, diagrams, and interface designs remain our intellectual property. Short quotations are welcome where accompanied by a visible credit and a followable link to the source page. Referenced standards remain the property of their respective standards bodies.
8. Third-Party Links
We link to manufacturers, standards bodies, and registration schemes for convenience. We do not control those sites, receive no editorial input into them, and are not responsible for their content, pricing, or privacy practices.
9. Changes & Governing Law
We may revise these terms as the site, its tools, or the underlying standards evolve; the "Last Updated" date above will always reflect the current version, and continued use after a change constitutes acceptance. These terms are governed by the laws of England and Wales. Questions about this policy can be sent via our contact page, and our data practices are described in the privacy policy.