Methodology

Where the figures come from

Every specification is transcribed from a manufacturer’s own product page, specification sheet, or installation manual. We read 33 distinct manufacturer documents to build this dataset. Each product page links the source we used and shows the date we last checked it, so you can verify any figure against the original rather than trusting us.

Where a retailer listing was the only source for something, we say so. Retailer listings are the least reliable tier in this dataset: they are frequently stale, and several of the 25 contradictions we document are a retailer disagreeing with the manufacturer it resells.

What we refuse to calculate

This is the core of the methodology. A specification directory is judged by what it does when the data runs out, and the tempting move is always to compute the missing value. We don’t.

• We never derive a breaker size from a kW rating. 40 of the 68 heaters here publish no breaker rating. The arithmetic is easy and the result would be wrong, because protective device sizing depends on the installation, the conductor, and the local code — not on the appliance rating alone. Those fields stay empty.
• We never derive a wire size from an amperage. Same reason, higher stakes.
• We never substitute family-level data for model-level data. 1 record in this dataset is flagged because its manufacturer publishes one specification sheet across several cabin sizes. We flag it rather than splitting one sheet into several invented per-size figures.
• We never sum multi-circuit supplies. Where a heater requires more than one supply circuit, each is listed separately. Adding two 40 A circuits into “80 A” produces a number that describes no real circuit and no real breaker.
• We never treat an amperage as a circuit requirement. 10 infrared cabins publish a current draw and never state whether the circuit must be dedicated. Those two facts stay separate.
• We never compute an interior volume from exterior dimensions. Wall thickness, benches, and heater clearances make the two different quantities, and sizing depends on the interior one.
• We never resolve a vague heater specification. 44 kits describe their included heater by brand, by kW, or not at all. We record the level of detail given; we do not guess the model.
• We never apply an outdoor or barrel label the manufacturer didn’t.
• We never place a 208 V or three-phase product into a residential 240 V filter unless that exact model is documented to support it.

How we handle contradictions

We found 25 cases where a manufacturer publishes two different values for the same specification. We do not pick a winner and we do not average them. Both values and both sources appear on the product page and on the source conflicts index.

There is one exception. Where our research established that a published value is an outright error — a clearance figure that contradicts the manufacturer’s own manual, for instance — we describe the conflict but withhold the erroneous figure rather than reproducing it as a specification. Republishing a wrong safety clearance because it appeared somewhere is not neutrality; it is a hazard with a citation.

Why there is no wiring guidance here

We publish planning checklists and the questions to ask. We do not publish wire sizes, conductor tables, or step-by-step wiring instructions, and we never will. The correct design depends on the exact product manual, the run length, ambient temperature, conduit fill, derating, and local code amendments, none of which we can see from here. Those decisions belong to the product manual, your local authority, and a qualified electrician.

What is deliberately absent

• No prices. Sauna equipment pricing changes constantly and varies by dealer. A stale price is worse than none.
• No star ratings, scores, or review counts. We have not surveyed owners, so any rating here would be invented or borrowed.
• No performance claims and no testing claims. We have not put a single one of these products in a room and measured it, and we will not imply otherwise.
• No “best” rankings. The right heater depends on your room’s volume, its surfaces, and your electrical supply. A universal ranking would have to ignore all three.
• No copied marketing copy. Specifications are facts and we transcribe them; descriptions are the manufacturer’s writing and we don’t reproduce them at scale.

Products we left out

25 products were considered and excluded, each with a stated reason recorded on the relevant category page — usually because the published data was too thin to represent honestly, or because sources conflicted so badly that no defensible record could be written. We would rather show you 145 products we can stand behind than a longer list padded with guesses.

Corrections

If a manufacturer changes a specification, or if we have transcribed something incorrectly, the fix is a data change with a new verification date, not a silent edit. If you spot an error — particularly an electrical one — please tell us and cite the manufacturer document, and we will correct it and re-date the record.