Methods

How we compare models

Our initial model directory is a selected research sample across five brands, not a complete market survey or a ranked recommendation list. We identify the model/configuration, intended-use scope, source and date. Specifications, prices and cooling claims are manufacturer statements unless a page explicitly reports a documented independent test. We have not independently tested the models in this directory.

A missing field stays unknown. Starting prices and temporary offers are labeled, and do not establish the installed cost. Cooling claims may use different test conditions and are not a quality score. A manufacturer’s commercial-use positioning does not establish facility approval, capacity or suitability at a particular site. Confirm the delivered configuration and applicable terms before ordering.

Model profiles, the model comparison and the source directory share their respective dated records. The warranty comparison is a separate, scoped analysis of published provisions. New source checks do not change the date of an older review or the terms of an earlier purchase.

How we count

We count owners, machines and incidents separately. One business with three machines is one owner and three physical units. Multiple posts about one machine do not become multiple owners. A whole-unit replacement is a new physical unit linked to its predecessor; a replaced component stays within the same unit record. An incident is a distinct reported problem episode, not each email, service visit or replaced part.

Owner reports are built only from voluntary submissions and public documents. They do not measure the failure rate of any brand’s products. Counts are published only with the observation period, the definitions used and the number of records with missing data.

What the evidence labels mean

Labels apply to a fact or a section, never as a blanket “verified” badge.

Label	Means	Does not mean
Owner account	A person submitted this description	Ownership or allegations independently verified
Ownership checked	A suitable purchase/ownership record was reviewed	Every event in the account is proven
Supporting documents reviewed	Identified documents support specified dates or events	Technical cause independently established
Technician finding	A named or identified professional’s report supports a particular finding	We conducted an engineering investigation
Company-confirmed point	An attributable company communication confirms that point	The entire dispute was admitted or resolved
Owner-confirmed resolution	The owner reports the stated outcome as of the displayed date	The product will never fail again

Checking an ownership document does not verify every allegation. We attribute technical findings to their source. We include successful outcomes and substantive company responses. A company’s silence is a dated fact about an inquiry, not an admission.

How the calculators work

Every calculator on this site follows the same rules, and every tool page shows its formula as ordinary text.

• Unknown stays unknown. A blank field is not zero. A missing required input means there is no total. An unknown optional category produces an incomplete subtotal that names what is missing — never an unqualified total that happens to be smaller.
• Zero means zero. If you enter 0, that is an affirmative zero: a rate of 0 means you chose not to value that time.
• Not calculable is an answer. A zero denominator returns “not calculable” with the reason, never 0, NaN or infinity.
• Decimal money. Arithmetic is exact and rounded only when shown.
• One currency per calculation. No automatic conversion.
• One economic event, one ID. Expenses and recoveries carry stable IDs. The same payment is never counted twice, even across tools.
• Three views, kept apart. Cash outlay, allocated or unpaid time, and incremental business impact are shown separately before any combined view.
• Nothing is built in. No industry average, failure rate, useful-life assumption, energy figure, repair probability or historical contract term is used to complete a form.
• Fictional examples are labeled. Loading a demo requires a deliberate action, and the label stays on the result.

Each tool page records its formula version and the date its method was last reviewed.

Downtime and availability

Availability uses half-open intervals. Overlapping unavailability within one unit is merged before it is added up. Outages are clipped to the unit’s active period and the observation window; an ongoing outage ends at the stated cutoff for calculation and stays marked ongoing. Business closure is measured for the owner’s own fleet, separately from pooled unit-time: a working machine at another business cannot offset a local closure. A zero denominator, or materially unknown operating status, means no percentage is shown.

Current public policies and earlier purchases

Current published terms establish current published text. They do not establish the terms that governed an earlier purchase. Where we compare provisions, we date them and identify the exact document.

How we use outside reviews

Other people publish about the brands we cover: consumer review platforms, complaint processes, owner communities and the companies’ own channels. We link to those places and describe what is there in our own words, with the date we looked. We do not copy a review, reproduce a platform’s score or rating graphic, name a reviewer, embed a widget, or collect reviews automatically. A platform’s terms and a reviewer’s copyright are separate questions from whether a link is accurate, and a link is not permission to reproduce.

A public review points to questions worth researching; it is not a verified case. It can tell us which questions to research. It does not tell us how many distinct owners exist: one person can post on several platforms, one machine can produce several incidents, and a review about a spa visit is not a review of a product. We never add one platform’s count to another’s. When a platform publishes its own totals we may state them with the date, because a count is a fact about the platform; we do not restate scores.

When an owner who posted elsewhere submits here, we link the accounts privately and count the person and the unit once. A public review is not consent to join this project, to receive messages from us, or to have identifying information shared with anyone.