How We Review Tankless Water Heaters
Our recommendations are only useful if you can trust how we reach them. Here is exactly how we evaluate every tankless water heater on this site — and, just as importantly, what we don't do.
Who does the reviewing
Reviews and recommendations are led by Mike Reynolds, Lead Reviewer at Tankless Geek, who has spent more than two decades working around residential plumbing, hot-water equipment and home-energy systems. That background shapes what we look at: not just headline flow rates, but the practical questions that decide whether a unit works in a real home — gas capacity, electrical service, water hardness and household demand.
Our review process
1. Selecting which units to cover
We focus on tankless water heaters that real homeowners are actually shopping for — models widely available from major retailers, across gas, propane and electric, and across price points from point-of-use units to whole-house systems. We prioritise units with a meaningful track record over brand-new releases with no ownership history.
2. Verifying the specifications
Every specification we publish — flow rate (GPM), temperature rise, energy factor, electrical requirements, venting and warranty — is checked against the manufacturer's own documentation, not repeated from marketing copy. Where a spec has real consequences for buyers (for example, the amperage and panel capacity an electric unit needs), we say so plainly and show the numbers.
3. Assessing real-world performance
Our star rating is an editorial verdict from Mike Reynolds — it weighs whether a unit delivers enough hot water for its intended home, what installation actually involves, how much maintenance it needs, and whether the price is justified. It is our informed opinion, not a laboratory measurement (see the honesty note below).
4. Factoring in owner feedback
We read through customer reviews to spot recurring, real-world issues — ignition faults, error codes, scale problems, support experiences. Where we cite a review count or average score, it is attributed to its source (typically Amazon) and reflects what was published there at the time of writing.
In the interest of honesty
- We do not run a physical test lab. We don't put every unit on a bench and measure it ourselves. Our assessments combine verified manufacturer specifications, hands-on industry experience, and documented owner feedback — and we're upfront that our star ratings are editorial judgement, not lab data.
- Specifications come from the manufacturer. When we quote a number, it's from the maker's published documentation. If a figure is an estimate or a typical range, we label it as one.
- Review counts belong to their source. Any rating or number of reviews we mention is attributed (usually to Amazon) and reflects a snapshot in time — live numbers change.
- We keep guidance current. Incentives, prices and models change; where a guide has been revised we show an "Updated" date so you know how fresh it is.
Editorial independence & how we're funded
Tankless Geek earns affiliate commissions when readers buy through some of our links — as an Amazon Associate we earn from qualifying purchases, at no extra cost to you. That funding keeps the site free, but it never buys a better review. We are not paid by manufacturers to feature or favour their products, and a commission link never changes a rating, a ranking or a recommendation.
If a popular unit has real drawbacks, we say so. Our only long-term asset is being right often enough that you come back.