Disclaimer — Estimates, Not Engineering

Estimates for information only

Every result produced by the calculators on this site is an estimate for informational purposes only. The sizing rule, the corrections and the fuel conversions are industry-standard rules of thumb — deliberately transparent, deliberately simple. They cannot see your site, your plumbing, your climate or your equipment, and they are not engineering calculations.

Before you buy or install

• The manufacturer datasheet wins. For any specific heater model, the official datasheet's ratings, efficiency figures, flow requirements and installation clearances govern. Nothing here overrides it.
• Gas work is licensed work. Heater installation involves gas lines, venting and electrical connections with code requirements that vary by jurisdiction. Use licensed professionals and pull the required permits.
• Check local codes. Equipment standards and installation codes change and differ locally; the federal efficiency floor cited on this site (10 CFR 430.32) is a minimum for manufacture, not a guide to what you should buy.

Sources and their limits

Figures on this site carry a source tag and a verification date. Sources can change: regulations get amended, agency guidance is revised, industry references disagree with each other. Where a figure is an editable default rather than a verified fact — fuel prices, for example — the page says so. A mismatch between a figure here and its official source should be reported via the contact page and will be corrected with a dated note.

No affiliation

This site is independent and heater-brand neutral. No manufacturer has reviewed or endorsed the content, and calculator results are never weighted toward any brand. Brand names that may appear in datasheet pages are trademarks of their owners, used only to identify the products the data describes.

Advertising and affiliate

If and when advertising is enabled, it is served by third-party networks and clearly labeled. Affiliate links, where present, are marked on the page and never alter calculator output. See the privacy policy for how third parties may use cookies.