How we pick

How we pick

The selection rules, the arithmetic, and the claims we refuse to make.

Most of this category ranks on hands-on testing, and some of those claims are genuine. Ours would not be, so we do not make it. There is no lab, no test rig, no unit in anyone's yard and no thermometer at nine feet.

That is a real limitation. It is also the reason this site does something different rather than something worse: a testing claim you cannot verify is worth less to you than arithmetic you can. Everything below is designed so that a stranger with a calculator can catch us being wrong.

1. 1It has to be currently sold. Every unit here was resolved to a live retail listing during the build. Where a listing could not be confirmed unambiguously, the product links to a search for its exact model rather than to a pinned page we are not sure about.
2. 2Its specifications have to be published by the maker. Gross heat input in BTU/h, rated wattage, fuel type and safety listing all come from the manufacturer's own documentation or listing, never from a retailer's marketing bullet and never from memory.
3. 3Its coverage claim gets labeled, not repeated. Where a maker publishes a heated radius or area, we quote it and say it is theirs. Where none exists, we compute one and say it is ours. We never present the second as the first.
4. 4It has to survive the arithmetic. A heater whose published output cannot warm the space its marketing implies does not get recommended for that space, however well it sells.
5. 5Something has to be wrong with it. Every product entry carries a stated `notFor` and a cons list. A pick with no downside is a pick nobody edited.

There is no field anywhere in this site's content model where a price, a running cost, a runtime or a coverage area can be typed by hand. Every one of them is computed at render time from a single shared formula module. That is the mechanical reason two pages here cannot disagree about the same heater — it is not diligence, it is that the alternative is not expressible.

Both energy prices above are national US averages with a named source and a date. They are almost certainly not your prices — regional electricity rates vary by more than a factor of three — which is why every cost page here shows the formula rather than only the answer, and why the cost page tells you where to find your own rate on your own bill.

There are none. This site publishes no numeric product scores, no star ratings and no aggregate ratings, and it emits no rating markup to search engines. A score implies an evaluation, and the only evaluation we performed is arithmetic on published figures — which is better expressed as the arithmetic itself.

What you get instead of a score is a one-line verdict in plain English, a `best for`, an explicit `not for`, and the computed numbers that produced both.

Prices are never written into a page. They are read from a live data layer that is refreshed on a schedule, and any figure older than 48 hours is suppressed automatically — the page falls back to "Check price on Amazon" rather than showing a number we cannot stand behind. Where a live price is displayed, the date it was verified is printed beside it.

• A published specification turns out to be wrong or is withdrawn by the maker.
• A safety listing we cited is revoked, or the unit is recalled.
• It stops being sold, and the search fallback stops finding an equivalent.
• Our own arithmetic, corrected, no longer supports the recommendation. This has the same weight as the others.

Commission rates are not on that list, in either direction. How this site is funded, and what we do when we get something wrong.