The standard

Intry Verified

A reading from any of the 51 Intry calculators in the table below carries the same four facts, in the same order, across both trades: what it was calculated from, what it was run with, how it was checked, and who has final say. This is the standard, so you can follow any number backwards without taking our word for it.

The four facts on a traced result

Calculated from

The exact authority the number came from: the cited NEC 2023 section for electrical tools, the manufacturer pressure-temperature data for refrigerant tools, the UL 60335-2-40 / ANSI/ASHRAE 15.2-2024 or AHRI-certified NEEP standard for A2L charge limits and cold-climate capacity, the EPA rule (40 CFR) for refrigerant compliance, the ACCA Manual J basis for load sizing, or the bender geometry for a bend. It is reused verbatim from the engine, never re-written for the page.

Run with

The exact inputs the engine consumed for that run: the materials, the terminal ratings, the conditions. A number is only correct given its inputs, so we show them. Nothing the engine did not use appears here.

Checked

How the number is held to its source. Before any deploy, an automated test suite does two things: it re-derives calculated figures from a locked data module so a number cannot be transcribed wrong onto the page, and it source-checks values against what they cite - the NEC section, the manufacturer chart, the federal rule - so a number is held to its real source, not just to itself. It is our own deterministic gate that runs on every update, not a third-party audit, and we say so.

Final say

Who has the last word, in plain terms. Your AHJ and local amendments on an electrical install, the unit nameplate and the manufacturer's charging chart on a refrigerant system, a full Manual J on the actual house. The standard's last line is deliberately not ours.

How a number earns it

Two rules make the standard checkable instead of aspirational. First, derive, never hand-type: every calculated number traces to a locked data module (an NEC table, a manufacturer PT chart), so it cannot be transcribed wrong. Second, declare, never restate: which authority governs a tool is declared once, in one place, so an HVAC result is structurally incapable of claiming the electrical code, and the reverse.

Those rules are enforced by a test suite that runs before every deploy. It does two jobs: it re-derives calculated figures from their locked source so a number cannot be transcribed wrong onto the page, and it source-checks values against the actual source they cite, so a number is held to its real source, not just to itself. When a covered value drifts from its source, or a new calculator ships without registering its check, the build stops and the change never ships. As of the current build that suite holds 30696 checks, and this very page passed through it.

Two things follow. First, a number is held to the code book, spec sheet, or federal rule it actually comes from, not to our own say-so. Second, it stays that way: the same gate runs on every future update, and every new calculator has to register its check before it can go live. This is our own deterministic gate, run on every build. It is not a third-party audit, and it is not a certificate on any one reading: your AHJ, the unit nameplate, and a full Manual J still have the last word.

The same discipline covers the pictures. On the conduit bending calculator, the interactive 3D bend is not a drawing: every vertex, arc, and mark is re-derived from the same locked engine that computes the marks, and the render is checked against that engine to a millionth of an inch before every deploy. So the pipe you spin, and the flat diagram beside it, cannot drift from the numbers they are built on.

The receipt for each traced calculator

One row for each of the 51 calculators whose result carries the Intry Verified trace: the authority its numbers are derived from, the code or data edition they are keyed to, and whether an AI assistant can run the tool and get a result that is checked against the locked engine on every deploy. This table is generated by the same gate it describes, and it is published as machine-readable JSON at /api/verified. The 30696 checks above gate every deploy as one suite; the receipt below adds no per-tool count, because a single check often guards several tools at once.

“Derived from” lists the documents the tool’s own source receipt names, generated from that one receipt so this table and the tool page cannot disagree. Where a tool has no receipt yet, it falls back to that tool’s declared authority phrase and says so by being shorter. “Runnable” means the calculator is exposed at the MCP endpoint, and that before each release an automated check confirms the answer it returns is identical to the one the website’s own engine produces.

A page that opens one of these calculators shares its row. Pages without the trace are not listed here, among them the fixed electric heat calculator for heat strips and electric furnaces, which prints its NEC sections on its own result; the refrigerant PT charts, which carry their own source receipt; and the furnace code lookup and the heat pump no-heat check, which quote the maker’s document and page for the codes and rules they show.

Where you see it

On each of the 51 calculators in the table above, under the result, there is a line that reads where this number comes from. Open it and you get the trace: the four facts for the exact reading on your screen, stamped with the build that checked it, in the same block and the same order. When an assistant runs one of the 18 that are exposed at the Intry MCP endpoint, its result names the source and how it was checked.