How our data works
Every specification and part number on this site comes from a manufacturer's own published document, and every page cites that document. This page explains how the numbers get from the PDF to the page, and what has and has not been checked by a person.
Where the data comes from
Two kinds of document, both published by the manufacturer:
- Spec sheets: the specification tables for a series of models (capacity, input, dimensions, efficiency ratings and so on).
- Parts lists: the replacement part numbers for a series, by model.
Installation manuals, brochures and selling guides are not used. The documents are not copied onto this site: each page links the manufacturer's own copy, and the link opens their PDF. A document the manufacturer no longer hosts is cited by name, without a link.
How values are read
The tables are read by software, from the position of each word on the PDF page. Converting a table to plain text loses its columns: when a cell is empty, every value after it slides one column to the left and lands under the wrong heading. Reading positions keeps each value in its own column, and an empty cell stays empty.
Manufacturers label the same thing in different ways ("1st Hour Rating", "First Hour Rating (Gal.)"), so each printed label is mapped to one fixed field, and the label as printed is kept with the value so a mapping mistake can be traced.
Every record then goes through plausibility checks that catch impossible values, such as a capacity off by a factor of ten. The checks flag problems; they never correct them. A record they reject is not published, and a model is published only when its core figures, such as capacity and input, were read.
When two revisions of a spec sheet both list a model, the newer document's figures are used for that model. An older revision stays the source for any model that only it lists.
Every figure is cited
Each model page ends with its sources: the spec sheet the page was built from and, where the manufacturer publishes one, the parts list. Each part page names the parts list it comes from, and the models it is shown to fit are the models that parts list gives it for, among the models this site publishes.
What "checked by hand" means
Some model pages carry the line "Specifications checked by hand", followed by the manufacturer whose document was checked. It appears only when a person opened the cited spec sheet, compared the specifications on the page with it value by value, and recorded the sign-off with its date. 125 of 328 model pages carry it today.
It covers specifications only. No parts list has been checked by hand against its document, on any model. A sign-off covers the values as they stood on the day it was made.
Missing values are shown as missing
If a value cannot be read with confidence, it is left out rather than guessed. A blank is an incomplete page; a plausible wrong number would be worse, because nothing would mark it as wrong.
Where a document does not publish a figure at all, the page says so: for example, older spec sheets that predate the 2015 efficiency standard print no UEF rating. Where a manufacturer publishes no parts list covering a model, the model page says that too.
Reporting an error
If a number here does not match the document it cites, email creativec702@gmail.com with the page address, the value, and what the document shows (the PDF page number helps). The report is checked against the cited document, and if the page is wrong it is corrected.