Boiler Size Calculator
Transparency & Quality Standards

Editorial & Corrections Policy

Last Updated: November 2026

Boiler Size Calculator provides open-access hydronic sizing tools, heat-loss formulas, and educational heating guides for homeowners, installers, and building services engineers. Because heating equipment specifications directly impact household fuel expenses and residential safety, we hold our platform to rigorous standards of accuracy, transparency, and independence.

1. Engineering Standards & Calculation Integrity

Every calculation engine and reference chart published on this site is benchmarked against recognized, published building services engineering standards:

  • BS EN 12831-1: Calculation of design heat load for building space heating.
  • CIBSE Domestic Heating Design Guide: Room design temperatures, distribution losses, and hot water reheating standards.
  • BS 6891:2015: Low-pressure gas pipework sizing and maximum allowable pressure loss limits (1.0 mbar).
  • BS 7074-1: Sealed system expansion vessel acceptance ratios and safety valve allowances.
  • BS EN 442: Radiator heat output ratings and Delta T exponent corrections ($n \approx 1.30$).
  • ACCA Manual J & Manual S: North American residential load and equipment selection.

We do not use simplified "rule-of-thumb" multipliers (e.g. arbitrary watts-per-square-foot) as final specifications. All equations are computed client-side in the user's browser without hidden weighting factors.

2. Commercial & Editorial Independence

Our sizing recommendations operate with complete autonomy:

  • No Manufacturer Affiliations: We do not receive sponsorship, kickbacks, or referral commissions from boiler manufacturers (such as Worcester Bosch, Vaillant, Baxi, Viessmann, Ideal, or Weil-McLain).
  • No Pay-to-Rank Placements: Equipment models highlighted in our brand matrices are selected based on verifiable technical specifications (such as wide 1:10 modulation ratios or stainless steel heat exchangers) rather than commercial partnerships.
  • Zero Data Gating: We do not lock calculation results behind email capture or phone number lead funnels.

3. Limitation of Planning Estimates

All calculations, charts, and recommendations published on this website are designed for preliminary planning, sizing estimation, and educational comparison.

They do not replace a licensed, on-site structural or hydronic survey. In the United Kingdom, all gas installation and pipework modifications are legally restricted to certified Gas Safe Registered engineers under the Gas Safety (Installation and Use) Regulations 1998. Equivalent statutory licensing applies across other jurisdictions (e.g. OFTEC in Ireland, EPA/NATE in the US).

4. Corrections & Discrepancy Reporting Process

We are committed to swift, transparent corrections when errors of fact, formula typos, or standard revisions are identified.

How to Submit a Calculation Correction:

Practicing engineers, installers, and researchers can submit technical corrections directly to our editorial desk:

Email: editorial@boilersizecalculator.com

Please include: (1) The URL of the page, (2) The specific formula or claim in dispute, and (3) The citation to the published standard (including standard number, edition year, and clause or table number).

Our team reviews all technical submissions within 1 to 2 business days. Verified errors are immediately corrected in code, and significant formula changes will be documented in our release notes.

5. Contact & Oversight

For inquiries regarding our editorial policy, standards methodology, or platform governance, visit our Contact Page or review our Terms of Service.