{"standard":"Intry Verified","spec":"https://www.intrysys.com/verified","homepage":"https://www.intrysys.com","suite":{"assertionCount":30696,"buildDate":"2026-10-06","commitShort":"e989bc2","note":"assertionCount is the number of automated checks that re-derive and source-check calculated figures against their locked source, and gate every deploy. It is a whole-suite count, not a per-tool count, and it is Intry's own deterministic gate, not a third-party audit."},"scope":"One receipt for each of the 51 Intry calculators whose result carries the Intry Verified trace. Pages without the trace are not listed, among them the fixed electric heat calculator, the refrigerant PT charts and the pages that quote a maker's document.","tools":[{"slug":"wire-size","name":"Wire Size Calculator","trade":"electrical","calculatedFrom":"NEC Table 310.16 · NEC 210.19(A) and 210.20(A) · NEC 110.14(C) · NEC 310.15(B)(1) with Table 310.15(B)(1)(1), and Table 310.15(C)(1) · NEC 240.6(A) and 240.4(B) · NEC 240.4(D) · NEC Table 250.122","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/electrical-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#wire-size"},{"slug":"voltage-drop","name":"Voltage Drop Calculator","trade":"electrical","calculatedFrom":"NEC Chapter 9, Table 9 · NEC Chapter 9, Table 8 · NEC 210.19 and 215.2 Informational Notes","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/electrical-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#voltage-drop"},{"slug":"conduit-fill","name":"Conduit Fill Calculator","trade":"electrical","calculatedFrom":"NEC Chapter 9, Table 1 · NEC Chapter 9, Table 4 · NEC Chapter 9, Table 5 · NEC Chapter 9, Note 7","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/electrical-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#conduit-fill"},{"slug":"box-fill","name":"Box Fill Calculator","trade":"electrical","calculatedFrom":"NEC Table 314.16(B)(1) · NEC 314.16(B)(1) through (B)(6) · NEC Table 314.16(A)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/electrical-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#box-fill"},{"slug":"ev-charger","name":"EV Charger Circuit Calculator","trade":"electrical","calculatedFrom":"NEC 625.41 and 625.42 · NEC 625.44, 625.54, and 210.21(B)(1) · NEC Table 310.16 · NEC 240.6(A), 240.4(B), 240.4(D), and Table 250.122 · NEC 110.14(C)(1)(a)(3), 334.80 and 250.122(B) · NEC Chapter 9 (voltage drop) and 210.19(A) · NEC Table 310.15(B)(1)(1) and Table 310.15(C)(1) · NEC 750.6, 750.30, and 750.50, energy management systems · NEC 625.42(B) + 750.30(C) + 110.3(B) · NEC 220.60 · NEC 230.79 and NEC 230.42(A)(1) · NEC 230.90 and NEC 240.4 · NEC 210.20(A)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/ev-charger-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#ev-charger"},{"slug":"load-calculator","name":"Existing-Load Panel Check (NEC 220.87)","trade":"electrical","calculatedFrom":"NEC 220.82 · NEC 220.87 · NEC 220.57 · NEC 210.20(A) · NEC 240.6(A)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/load-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#load-calculator"},{"slug":"heat-pump-water-heater-circuit","name":"Water Heater Circuit Calculator","trade":"electrical","calculatedFrom":"NEC 422.13 · NEC 210.20(A) · NEC Table 310.16 and NEC 110.14(C) · NEC 240.6(A) and 240.4(D) · NEC Table 250.122 · NEC 210.23(B) and 210.23(B)(2) · NEC 210.19(A) and 210.20(A)","edition":"NEC 2023","editionNote":null,"finalSay":"The unit nameplate has the final say on the breaker; your AHJ and local amendments govern the install.","engineModule":"src/lib/tools/water-heater-circuit-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#heat-pump-water-heater-circuit"},{"slug":"120v-induction-range-circuit","name":"120V Induction Range Circuit Calculator","trade":"electrical","calculatedFrom":"NEC 210.23(B)(1) and 210.23(B)(2) · NEC 210.21(B)(2) and Table 210.21(B)(2) · NEC 210.20(A) and Article 100 (continuous load) · NEC 210.19(C) · NEC Table 220.55 · NEC Table 310.16, 240.4(D), and Table 250.122 · NEC 110.14(C)(1)(a)(3) and 334.80","edition":"NEC 2023","editionNote":null,"finalSay":"The unit rating plate has the final say on the wall/charge draw; your AHJ and local amendments govern the install.","engineModule":"src/lib/tools/induction-range-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#120v-induction-range-circuit"},{"slug":"ev-load-management-calculator","name":"Biggest EV Charger Calculator (EVEMS)","trade":"electrical","calculatedFrom":"NEC 220.87 · NEC 220.70 · NEC 625.42 and 750.30 · NEC 210.20(A) and 625.41 · NEC Table 310.16 · NEC 110.14(C)(1)(a)(3) and 334.80 · NEC 240.6(A), 240.4(D), and Table 250.122 · NEC 750.30(C)(1) through (C)(4), and 750.50 · NEC 220.60 · NEC 210.20(A) · NEC 230.90 and NEC 240.4 · NEC 110.3(B)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and your actual metered demand have final say; any EVEMS must be listed and installed per its instructions, and the branch is always sized to the full charger output.","engineModule":"src/lib/tools/ev-load-management-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#ev-load-management-calculator"},{"slug":"conduit-bending","name":"Conduit Bending Calculator","trade":"electrical","calculatedFrom":"Bender-manufacturer offset multiplier table · Bend geometry (trigonometry) · Bender-manufacturer 3-point saddle table · Bender-manufacturer shrink-per-inch table · Hand-bender take-up (EMT) and gain (every type)","edition":null,"editionNote":"NEC 2023 Chapter 9 Table 2 (minimum bend radii), for the feasibility check only; the bend math is geometry and the bender maker's chart","finalSay":"Field-verify against the actual bend. Bender take-up varies by tool and shoe.","engineModule":"src/lib/tools/bending-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#conduit-bending"},{"slug":"mca-mocp","name":"MCA & MOCP Breaker Calculator","trade":"hvac","calculatedFrom":"NEC 440.33, 440.34, 440.35 and 430.24 · NEC 440.22, 440.22(A) and 440.22(B)(1) · NEC 240.6(A) · NEC 240.4(G) (Article 440) · NEC 440.1, 440.21, 424.4(B) and 424.19 (a circuit with no compressor) · NEC 310.15(B)(1) and 310.15(C)(1) · NEC 310.15(B)(2) · NEC 110.14(C) · NEC 440.14, 440.12 and 110.26(A) · NEC 440.52 · NEC Table 310.16 · NEC Table 250.122 · NEC 440.4(B) and 110.3(B) · NEC Chapter 9 (voltage drop) and 210.19(A)","edition":"NEC 2023","editionNote":null,"finalSay":"The unit nameplate has final say. NEC Article 440 governs the sizing.","engineModule":"src/lib/tools/mca-mocp-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#mca-mocp"},{"slug":"changeout","name":"A2L Changeout Circuit Check","trade":"hvac","calculatedFrom":"NEC 440.4(B) and 110.3(B) · NEC 440.35 and 440.4(B) · NEC Table 310.16 · NEC 310.15(B)(1) and 310.15(C)(1) · NEC 310.15(B)(2) · NEC 110.14(C) · NEC 440.22, 440.22(A) and 440.22(B) · NEC 240.6(A) · NEC 240.4(G) (Article 440) · NEC 440.14, NEC 440.12 and NEC 110.26(A)","edition":"NEC 2023","editionNote":null,"finalSay":"The marked nameplate has final say. NEC Article 440 governs the sizing, and your AHJ has the last word.","engineModule":"src/lib/tools/mca-mocp-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#changeout"},{"slug":"superheat-subcooling","name":"Superheat & Subcooling Calculator","trade":"hvac","calculatedFrom":"CEC-400-2022-010-AP, Reference Appendix RA3 Table RA3.2-1 (Installer Testing at Final) · CEC-400-2022-010-AP, Reference Appendix RA3 Table RA3.2-2 (target superheat) · CEC-400-2022-010-AP, Joint Appendix JA6.1.6.3 (the airflow precondition) · Carrier PH5SAN5, Carrier SM10-R454B-03, Carrier 25SCA5, Goodman IOG-4048C, ICP 428 01 5106 00, Trane 88-M5MHWUN-1A-EN, Rheem RD16AY, and Bosch service literature · The per-machine charge-target corpus (registered manufacturer books, cited by form number) · The heat pump's heating-mode check (each maker's own heat pump book, cited by form number and page) · York ST-022-12, Figures 1 and 2 (example charging charts) · Rheem RD16AY / RD18AY section 5.7, and Lennox 13ACX 506374-01 page 20 · Copeland discharge-temperature guidance, and Proctor Engineering on airflow and capacity · The manufacturer installation books these steps quote","edition":null,"editionNote":"CEC Title 24 Tables RA3.2-1 (installer compliance criteria) and RA3.2-2 (fixed-orifice target superheat); the rest is manufacturer data and physics","finalSay":"The unit nameplate and the manufacturer's charging chart have final say.","engineModule":"src/lib/tools/superheat-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#superheat-subcooling"},{"slug":"cold-climate-hp-capacity","name":"Cold-Climate Heat Pump Capacity Calculator","trade":"hvac","calculatedFrom":"AHRI-certified NEEP ccASHP database · Manufacturer submittal · Linear interpolation of the MAX-capacity curve (derived)","edition":null,"editionNote":null,"finalSay":"The manufacturer's engineering data or a Manual-J load calculation by an HVAC pro has final say.","engineModule":"src/lib/tools/cold-climate-hp-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#cold-climate-hp-capacity"},{"slug":"line-set","name":"A2L Line Set Calculator","trade":"hvac","calculatedFrom":"Goodman/Amana IOG-4047 · Carrier LLG-R454B-01 · Goodman/Amana IOG-4047, p.1 (changeover cautions) · An R-410A line, and the pressures the cautions print · Carrier R-454B FAQ, Bosch A2L Change Guide, Lennox/York R-454B IOMs","edition":null,"editionNote":null,"finalSay":"The manufacturer's installation guide for your exact unit has final say.","engineModule":"src/lib/tools/line-set-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#line-set"},{"slug":"a2l-charge-limit","name":"A2L Refrigerant Charge Limit Calculator","trade":"hvac","calculatedFrom":"UL 60335-2-40 (4th ed) Annex GG · ANSI/ASHRAE 15.2-2024 · ASHRAE 34-2019 Addendum f (LFL values) · IEC 60335-2-40 ed 6 / EN 378 (gravity-only)","edition":"UL 60335-2-40 4th ed / ANSI/ASHRAE 15.2-2024","editionNote":null,"finalSay":"The equipment listing and the manufacturer's installation manual for your exact unit, plus your AHJ, have final say.","engineModule":"src/lib/tools/a2l-charge-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#a2l-charge-limit"},{"slug":"outdoor-hvac-gfci","name":"Outdoor HVAC GFCI Requirement (NEC 210.8(F))","trade":"electrical","calculatedFrom":"NEC 2023 and NEC 2020, 210.8(F), read from the printed book · TIA 20-19 and TIA 23-3, the lineage of the exception itself · Each state's own amendment to 210.8(F), where we hold it · Each state's own current-code listing, for what is in force today · The compiled adoption dataset, published as the weaker source","edition":"NEC 2023","editionNote":null,"finalSay":"This answer holds only for the jurisdictions whose amendments we have read from their own primary documents. Everywhere else the tool refuses, and your AHJ has the final say in every case.","engineModule":"src/lib/tools/gfci-210-8f-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#outdoor-hvac-gfci"},{"slug":"btu","name":"BTU / HVAC Load Calculator","trade":"hvac","calculatedFrom":"ACCA Manual J (simplified): the load model · ACCA Manual S, Table N2-1: the equipment-fit window · IECC 2021 climate zones (the zone boundaries only) · ACCA Manual S (equipment fit) · NREL/TP-5500-60801 (November 2014): the oversizing energy penalty, and its scope · ENERGY STAR Room Air Conditioner sizing table","edition":null,"editionNote":null,"finalSay":"A full Manual J on the actual house has final say.","engineModule":"src/lib/tools/btu-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#btu"},{"slug":"solar-backfeed","name":"Solar Backfeed Breaker Calculator (NEC 705.12)","trade":"electrical","calculatedFrom":"NEC 705.12(B)(2) · NEC 705.12(B)(1) · NEC 408.36 · NEC 240.6(A)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and the utility interconnection agreement have final say; confirm the panel's busbar rating and that the backfeed sits at the opposite end of the bus from the main.","engineModule":"src/lib/tools/load-calc.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#solar-backfeed"},{"slug":"sub-panel","name":"Sub-Panel Wire Size Calculator","trade":"electrical","calculatedFrom":"NEC Table 310.16 · NEC Table 250.122 · NEC 240.6(A) · NEC Chapter 9 and 215.2(A) · NEC 215.6, 408.40, and 250.24 · NEC 250.32","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/sub-panel-data.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#sub-panel"},{"slug":"neutral-ccc","name":"Neutral Current-Carrying Conductor","trade":"electrical","calculatedFrom":"NEC 2023 310.15(E), neutral conductor · NEC 2023 310.15(F), grounding or bonding conductor · NEC 2023 Table 310.15(C)(1) and its footnote · NEC 2023 Table 310.16, Equation 310.15(B)(1) and 110.14(C)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ has final say. NEC 310.15(E)(3) turns on whether the major portion of the load is nonlinear and the code prints no percentage for that, so this tool asks you for it rather than supplying a threshold of its own.","engineModule":"src/lib/tools/neutral-ccc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#neutral-ccc"},{"slug":"tap-conductor","name":"Tap Conductor Calculator","trade":"electrical","calculatedFrom":"NEC 2023 240.21(B)(1) through (B)(5), feeder taps · NEC 2023 240.21(B) preamble, no next-size rounding on a tap · NEC Table 310.16, allowable ampacities","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ has final say. This sizes the conductor; the conditions each tap rule places on the installation still have to be met on the job.","engineModule":"src/lib/tools/tap-conductor-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#tap-conductor"},{"slug":"transformer-ocpd","name":"Transformer OCPD Calculator","trade":"electrical","calculatedFrom":"NEC 2023 450.3(B) and Table 450.3(B), with Notes 1, 2 and 3 · NEC 2023 240.6(A) and Table 240.6(A), standard ampere ratings · NEC 2023 240.4(F) and 240.21(C)(1), primary-only protection","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ has final say. Table 450.3(B) gives maximums, so a smaller device is usually permitted and often required by the load, the conductors or the transformer inrush.","engineModule":"src/lib/tools/transformer-ocpd-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#transformer-ocpd"},{"slug":"three-phase-motor","name":"Three-Phase Motor Calculator","trade":"electrical","calculatedFrom":"NEC 2023 Table 430.250, Full-Load Current, Three-Phase AC Motors · NEC 2023 Table 430.248, Full-Load Currents, Single-Phase AC Motors · NEC 2023 430.6(A)(1), which current to use · NEC 2023 430.22, Table 310.16 and 110.14(C)(1)(a), the conductor · NEC 2023 430.52(C)(1) with Table 430.52, and 240.6(A) standard ratings · NEC 2023 240.4(G) and Table 240.4(G), why a motor branch circuit may sit under a larger breaker","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ has final say. The table current sizes the branch circuit; your motor's nameplate sizes the running overload device (430.32), which this tool does not size. Wound-rotor and DC motors take a different percentage from Table 430.52 and are out of scope.","engineModule":"src/lib/tools/motor-flc-data.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#three-phase-motor"},{"slug":"what-size-breaker-do-i-need","name":"What Size Breaker Do I Need","trade":"electrical","calculatedFrom":"NEC 240.6(A) and 210.20(A) · NEC Table 310.16, 240.4(B) and 240.4(D) · NEC Table 250.122 · NEC 424.4(B), 424.22(B), 110.14(C)(1) and 110.3(B) (fixed electric heat) · NEC 210.19(C) and Table 220.55 · NEC 422.13, 625.41 and 625.42 · NEC Article 440 and Article 430","edition":"NEC 2023","editionNote":null,"finalSay":"The equipment nameplate has the final say for nameplate-rated loads (HVAC, motors, welders, spas); your AHJ and local amendments govern the install.","engineModule":"src/lib/tools/breaker-by-load-data.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#what-size-breaker-do-i-need"},{"slug":"conductor-capacity","name":"Conductor Capacity Check","trade":"electrical","calculatedFrom":"NEC Table 310.16 · NEC Equation 310.15(B)(1) · NEC Table 310.15(C)(1) · NEC 110.14(C) · NEC 210.19(A)(1) and 210.20(A) · NEC 240.4(D) · NEC 240.6(A) · NEC Table 250.122 · NEC Chapter 9, Table 9","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/conductor-capacity-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#conductor-capacity"},{"slug":"ampacity-derating","name":"Ampacity Derating Calculator","trade":"electrical","calculatedFrom":"NEC Equation 310.15(B)(1) · NEC Table 310.15(B)(1)(1) · NEC 310.15(B)(2) · NEC Table 310.15(C)(1) · NEC Table 310.16 · NEC 110.14(C) · NEC 240.4(D) · NEC 240.6(A)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/ambient-correction-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#ampacity-derating"},{"slug":"egc-sizer","name":"Ground Wire Size Calculator","trade":"electrical","calculatedFrom":"NEC Table 250.122 · NEC 250.122(B) · NEC 250.122(A) · NEC Chapter 9, Table 8 · NEC Table 310.16, Table 310.15(B)(1)(1) and Equation 310.15(B)(1), Table 310.15(C)(1), 210.19(A)(1) and 215.2(A)(1) · NEC 240.4(B) and 240.4(D)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/egc-sizer-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#egc-sizer"},{"slug":"next-standard-size","name":"Next Standard Size Calculator","trade":"electrical","calculatedFrom":"NEC Table 240.6(A) · NEC 240.4(B) · NEC 240.4(D), and the reason it outranks the round-up · NEC 240.4(G) and Table 240.4(G): the Article 440 air-conditioning and refrigeration exception · NEC Table 310.16 and 110.14(C) · NEC Table 250.122","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/next-standard-size-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#next-standard-size"},{"slug":"box-picker","name":"Box Picker","trade":"electrical","calculatedFrom":"NEC Table 314.16(A) · NEC 314.16(B)(1) · NEC 314.16(B)(2) through (B)(6)","edition":"NEC 2023","editionNote":null,"finalSay":"Your AHJ and local amendments have final say. Confirm before rough-in.","engineModule":"src/lib/tools/box-picker-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#box-picker"},{"slug":"nitrogen-pressure-test","name":"Nitrogen Pressure Test Calculator","trade":"hvac","calculatedFrom":"NIST standard atmosphere (101,325 Pa) · NIST SP 811 Fahrenheit-to-Rankine offset (459.67) · Gay-Lussac's law (constant volume)","edition":null,"editionNote":null,"finalSay":"The equipment manufacturer and your AHJ have the final say on the required test pressure, the hold time, and pass or fail.","engineModule":"src/lib/tools/nitrogen-pressure-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#nitrogen-pressure-test"},{"slug":"dual-fuel-switchover","name":"Dual-Fuel Switchover Calculator","trade":"hvac","calculatedFrom":"16 CFR 305 Appendix K1 (FTC EnergyGuide), the 3,412 and 100,000 Btu constants · AHRI 210/240 rating conditions, and the defrost correction · EPA ENERGY STAR certified heat pump data (data.energystar.gov), plausibility-filtered · Manufacturer thermostat installer documentation","edition":null,"editionNote":null,"finalSay":"The equipment manufacturer's dual-fuel guidance and the building's behavior in a cold snap have the final say. Set the lockout at or above the thermal balance point, not the economic crossover, so a cold snap never strands the load.","engineModule":"src/lib/tools/dual-fuel-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#dual-fuel-switchover"},{"slug":"combustion-air","name":"Combustion Air Calculator","trade":"hvac","calculatedFrom":"IFGC 2021 Section 304.5, the 50 ft3 per 1,000 Btu/h confined-space threshold · IFGC 2021 Section 304.1, outdoor air where indoor air falls short · IFGC 2021 Section 304.6, outdoor opening divisors · IFGC 2021 Section 304.7, combining indoor and outdoor air · IFGC 2021 Sections 304.5.2, 304.5.3, 304.9 and 304.10","edition":null,"editionNote":"IFGC 2021 Section 304 (NFPA 54 9.3 cited beside it)","finalSay":"The authority having jurisdiction and the appliance manufacturer's instructions have final say. This never certifies a space safe: a real combustion-air problem is confirmed by a draft, spillage, or CO test.","engineModule":"src/lib/tools/combustion-air-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#combustion-air"},{"slug":"gas-pipe-sizing","name":"Gas Pipe Sizing Calculator","trade":"hvac","calculatedFrom":"Chapter 4 of the fuel gas code, which is MANDATORY: the sizing equation, the Cr and Y values, and the three length methods · The published capacity tables, used as a floor under every steel, copper and polyethylene answer at the drop the table is printed for and at any tighter drop, and as the equation's validation set · Copper and polyethylene bores, and CSST capacities, read from the code's own tables · Section 402.6 of the fuel gas code, the pressure at each appliance inlet · The appendix's own worked examples, used as an independent check · Appendix A, which says in its own first line that it is INFORMATIVE and not part of the code","edition":null,"editionNote":"no single edition: the fuel gas code family (IFGC, IRC, NFPA 54 or UPC) is chosen on the page and each is cited by its own address","finalSay":"The authority having jurisdiction and the appliance manufacturer's instructions have final say. This computes the code-required size and never certifies an installation: a real problem is confirmed by a manometer reading at the appliance inlet under full load.","engineModule":"src/lib/tools/gas-pipe-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#gas-pipe-sizing"},{"slug":"manual-j-load","name":"Manual J Load Calculator","trade":"hvac","calculatedFrom":"ACCA Manual J, 8th Edition, Abridged Edition (MJ8AE), Form J1 and Form J1ae · ASHRAE Handbook of Fundamentals 2021, Chapter 14, climatic design conditions · US Census Bureau 2020 Gazetteer Files, ZIP Code Tabulation Areas (ZCTA5)","edition":null,"editionNote":"ACCA Manual J 8th Edition (the load procedure) with the ASHRAE Handbook of Fundamentals 2021 Chapter 14 design conditions; not a code table","finalSay":"A full permit-grade ACCA Manual J has final say. This is not ACCA-approved: its whole-house heating total rests on four site conditions you declare, and its cooling load rests on two more. It reports a whole-house COOLING load as the PAIR Manual J section 5-12 sizes equipment from: the total sensible load (Form J1ae line 20) and the total latent load (line 21). Either is withheld when a printed term of it is unanswered or has no printed route in the abridged edition, and the specific term is named on the result rather than folded in.","engineModule":"src/lib/tools/manual-j-load.ts","runnable":true,"resultMatchesEngine":true,"receipt":"https://www.intrysys.com/verified#manual-j-load"},{"slug":"cfm","name":"CFM Calculator","trade":"hvac","calculatedFrom":"HVAC School sensible-heat basis (1.08) · ACCA 400 CFM per ton airflow rule","edition":null,"editionNote":null,"finalSay":"The OEM blower table for the actual coil, or a full ACCA Manual J/D design, has final say.","engineModule":"src/lib/tools/duct-airflow-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#cfm"},{"slug":"duct-size","name":"Duct Size Calculator","trade":"hvac","calculatedFrom":"ASHRAE Fundamentals duct-friction model (Darcy-Colebrook) · ASHRAE Fundamentals 21.3.1 equivalent diameter (Huebscher) · Standard manufactured duct sizes (McGill AirFlow / SMACNA) · Advisory design targets (Manual D basis, hvacprosales velocity bands)","edition":null,"editionNote":null,"finalSay":"A full ACCA Manual D duct design and the equipment's blower data have final say.","engineModule":"src/lib/tools/duct-airflow-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#duct-size"},{"slug":"duct-round-rect","name":"Round to Rectangular Duct Converter","trade":"hvac","calculatedFrom":"ASHRAE Fundamentals 21.3.1 equivalent diameter (Huebscher) · Standard manufactured duct sizes (McGill AirFlow / SMACNA)","edition":null,"editionNote":null,"finalSay":"A full ACCA Manual D duct design has final say; confirm the shape fits the space.","engineModule":"src/lib/tools/duct-airflow-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#duct-round-rect"},{"slug":"static-pressure","name":"Static Pressure & Friction Rate Calculator","trade":"hvac","calculatedFrom":"ACCA Manual D friction-rate relation · Total effective length inputs (Manual D Appendix 3)","edition":null,"editionNote":null,"finalSay":"The blower's measured external static pressure and a full ACCA Manual D duct design have final say.","engineModule":"src/lib/tools/duct-airflow-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#static-pressure"},{"slug":"temp-rise","name":"Furnace Temperature Rise Calculator","trade":"hvac","calculatedFrom":"Your unit's rating plate (the temperature rise range) · Carrier Service and Technical Support Manual 440 04 4321 10, gas furnace (F/G)9MXT · Velocity Boiler Works Installer's Information Manual 431570g, Section 20 · The sensible-heat relation, for the airflow figure only · 10 CFR 430.2, for what AFUE is and is not","edition":null,"editionNote":null,"finalSay":"The rating plate and the manufacturer's installation instructions for your model have final say, and a combustion analysis is what confirms the furnace is safe. A rise inside the plate band is not a clean bill of health.","engineModule":"src/lib/tools/temp-rise-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#temp-rise"},{"slug":"vacuum-decay","name":"Vacuum Decay Test Calculator","trade":"hvac","calculatedFrom":"The installation instructions for your equipment (the hold criterion) · Trane Installer's Guide, Condensing Units, 18-AC98D1-5-EN (4TTR6018-061) · Goodman / Amana Condensing Unit Installation & Service Reference, IOG-4036B, December 2022 · York Installation Manual, R-410A 2-Stage Outdoor Split-System Heat Pump, 5391577-UIM-B-0718 (YZT, HC19B, HL19B) · Rheem / Ruud Variable Speed R-454B Heat Pump Outdoor Units Installation Instructions, 92-110354-01-01 · Carrier 26SCA5 Installation Instructions, 26SCA5-1SI, Edition Date 06/24 · Daikin Room Air Conditioner Installation Manual, 3P740830-1B · Daikin VRV Commissioning Guide (a training handbook, not an installation manual), VRV III Pre-Commissioning Check #3 · NIST Chemistry WebBook, Antoine parameters for water (Bridgeman & Aldrich, 1964) · The manufacturer installation books these steps quote","edition":null,"editionNote":null,"finalSay":"The installation instructions for your equipment have final say on the hold criterion, and a nitrogen pressure test is what locates a leak. A system that holds a vacuum has not been pressure tested.","engineModule":"src/lib/tools/vacuum-decay-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#vacuum-decay"},{"slug":"leak-rate","name":"EPA Refrigerant Leak Rate Calculator","trade":"hvac","calculatedFrom":"40 CFR 84.106 (AIM Act HFC leak repair) · 40 CFR 84.102 (Leak rate definition) · 40 CFR 84.108 (Automatic leak detection) · 40 CFR 82.157 (Section 608) and part 84 GWP tables · 89 FR 82700 (data center cooling is comfort cooling for ER&R) and 40 CFR 84.54(c)(13) · R-515B composition: 85 FR 79863 at 79865 and 79869 (SNAP listing), ASHRAE 34 designations, Honeywell DS-21-12-EN · The federal rules the refrigerant lines cite","edition":null,"editionNote":null,"finalSay":"The EPA rule text and a Section 608-certified technician have final say on coverage, thresholds, and reporting.","engineModule":"src/lib/tools/leak-rate-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#leak-rate"},{"slug":"purge-pump-out","name":"Chiller Purge Pump-Out Leak Check","trade":"hvac","calculatedFrom":"Trane CTV-SVX05H-EN (August 2020), page 7, Figure 2 · Trane CTV-SVX05H-EN, page 8: what the figure does not give · Trane CVHE-SVX02P-EN (October 2019), CVHE, CVHF, and CVHG Water-Cooled CenTraVac Chillers, Installation, Operation, and Maintenance: Leak Checking Based on Purge Pump Out Time, page 91 · 40 CFR 82.157(a) and 84.106(a)(3)(i); Table 1 to 84.64(b) · The federal rules the refrigerant lines cite","edition":null,"editionNote":null,"finalSay":"Trane's service literature for your CenTraVac and a Section 608-certified technician have final say; the leak repair rules turn on refrigerant added, which the leak-rate calculator applies.","engineModule":"src/lib/tools/purge-band-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#purge-pump-out"},{"slug":"blend-top-off","name":"Refrigerant Blend Top-Off Check","trade":"hvac","calculatedFrom":"Chemours Opteon and Freon product information sheets · Chemours temperature-glide bulletin and the 407C/407A bulletin C-11261 · Chemours Freon 407C Retrofit Guidelines C-11107, Influence of Leak/Recharge on Performance · Chemours Opteon FAQ C-10677; Honeywell Solstice N40 and N15 data sheets · 40 CFR 84.106(b) · This site's CoolProp 8.0.0 run (2026-09-07), for the R-450A glide check only","edition":null,"editionNote":null,"finalSay":"The refrigerant manufacturer and the equipment manufacturer have final say on charging a blend after a leak; a Section 608-certified technician does the work.","engineModule":"src/lib/tools/blend-topoff-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#blend-top-off"},{"slug":"chiller-retrofit","name":"R-134a Chiller Retrofit Eligibility","trade":"hvac","calculatedFrom":"EPA SNAP, Substitutes in Centrifugal Chillers (page last updated March 19, 2026) · Johnson Controls / YORK SI0389 (226) and SI0390 (919) · Chemours Opteon XP10 Retrofit Guidelines C-10302 (11/15) and Product Information C-10020; Honeywell R-513A chiller retrofit guide (2023) · Chemours Opteon XP30 C-10864; AGC AMOLEA 1224yd Technical Information (2019); Honeywell Solstice N13 retrofit guideline · This site's CoolProp 8.0.0 cycle model, and 40 CFR 84.106(b) and 84.54 · The federal rules the refrigerant lines cite","edition":null,"editionNote":null,"finalSay":"EPA's SNAP listing decides whether the retrofit is a listed use; the chiller's manufacturer has final say on whether a given machine can be converted and what tonnage it makes afterward; a Section 608-certified technician does the work.","engineModule":"src/lib/tools/chiller-retrofit-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#chiller-retrofit"},{"slug":"chiller-approach","name":"Chiller Condenser Approach Temperature","trade":"hvac","calculatedFrom":"Trane CVHH-SVX001J-EN (October 2019), CVHH Water-Cooled CenTraVac Chillers With Tracer AdaptiView Control, Installation, Operation, and Maintenance: Recommended Maintenance, Condenser, page 110 · YORK Form 160.75-O1 (425), Issue Date 2025-04-24, Model YK Style G with R-134a, R-513A, or R-1234ze, Operations Guide: Operating log sheet (page 16) and Daily inspections (page 17) · This site's PT tables (the superheat and subcooling engine), for saturation from pressure · The effectiveness-NTU algebra, re-run by this site on 2026-09-08 (the derivation behind the illustration table) · Trane CTV-SVX05H-EN Figure 2, through the purge tool · Johnson Controls / YORK SI0389 (226), the YK R-134a to R-513A conversion bulletin","edition":null,"editionNote":null,"finalSay":"The chiller's manufacturer and its service literature have final say on what the machine's approach should be and when the tubes are cleaned; this tool compares only to the commissioning record you enter, scaled to the present load.","engineModule":"src/lib/tools/chiller-approach-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#chiller-approach"},{"slug":"tonnage-from-model","name":"Tonnage From Model Number","trade":"hvac","calculatedFrom":"The BTU/1000 capacity ladder (024 = 2 tons) · Per-brand model nomenclature (fixed capacity position) · The forms each capacity position is read from, and the refusals they force · Mini split direct BTU class, and the LG single-zone legend that is not one · The independent capacity backtest (AHRI Certification Directory) · The packaged and light commercial lines and the maker forms behind them · Furnace MBH exclusion, the estimate fallback, and when the tool refuses · Maker documents behind series this tool decodes or estimates, and air handlers it gives no tonnage for · The manufacturer documents that identify these models","edition":null,"editionNote":null,"finalSay":"The unit's rating plate and its BTU/h rating have final say; brand nomenclature varies and changes across product generations.","engineModule":"src/lib/tools/model-tonnage.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#tonnage-from-model"},{"slug":"serial-number-lookup","name":"HVAC Serial Number Lookup","trade":"hvac","calculatedFrom":"What each date-code scheme rests on · How the decoder is checked against dated serials · The documents behind those checks · Carrier family and the ICP reversal · Trane, Goodman, Lennox, Allied, Rheem, York date codes · Ambiguous and non-encoded formats · Refrigerant era and warranty context by year · The federal rules the refrigerant lines cite · Two York documents that bound a York serial's date · The manufacturer documents that identify these models · The warranty certificates the warranty lines rest on · The gas furnace warranty certificates the furnace lines rest on · Which of these documents also date furnaces · U.S. Consumer Product Safety Commission recall notices (the recall lines) · The secondary references these rules are compiled from","edition":null,"editionNote":null,"finalSay":"The date printed or stamped on the data plate (the MFG DATE field, where present) has final say, and the nameplate refrigerant governs over any year-based era mapping.","engineModule":"src/lib/tools/serial-decoder.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#serial-number-lookup"},{"slug":"water-heater-age","name":"Water Heater Age Decoder","trade":"hvac","calculatedFrom":"Bradford White: the consumer date-code page and the For the Pro bulletin · Rheem, Ruud and Richmond: Technical Service Bulletin 1207","edition":null,"editionNote":null,"finalSay":"The date printed on the rating plate has final say. Where a serial genuinely carries more than one possible date, this tool shows every one it can and publishes no age, and the manufacturer's own warranty verification is what settles a claim.","engineModule":"src/lib/tools/water-heater-decoder.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#water-heater-age"},{"slug":"nema-plug-chart","name":"NEMA Plug & Receptacle Identifier","trade":"electrical","calculatedFrom":"Hubbell Configuration Chart (Wiring Device-Kellems) · Leviton Industrial Wiring Devices Catalog · Leviton product pages, straight blade 30A / 50A / 60A · Eaton Arrow Hart colour-coded locking devices selector guide","edition":null,"editionNote":null,"finalSay":"The rating stamped on the device face has final say. A configuration publishes here only where two independent manufacturers print it and agree. Blade dimensions live in NEMA WD 6 and are a separate layer we have not added yet.","engineModule":"src/lib/tools/nema-config.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#nema-plug-chart"},{"slug":"target-superheat","name":"Target Superheat Calculator","trade":"hvac","calculatedFrom":"the locked CEC Title 24 RA3.2-2 charging table it was computed from, which agrees cell for cell with one manufacturer piston grid and runs a mean 4.77F above another, on the sixth of the table where any manufacturer check exists","edition":null,"editionNote":"CEC Title 24 Table RA3.2-2","finalSay":"The manufacturer's charging chart for your exact fixed-orifice unit has final say, and where one exists it governs over this table.","engineModule":"src/lib/tools/target-superheat-calc.ts","runnable":false,"resultMatchesEngine":null,"receipt":"https://www.intrysys.com/verified#target-superheat"}]}