Codes & Standards
Federal HVAC rules, efficiency standards, permits, tax credits and rebates, with effective dates and citations checked against the eCFR and Federal Register.
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Crawl Space Ventilation: Vented or Sealed, Settled by Code and Building Science
IRC R408 gives crawl space ventilation two legal paths: vent at 1 square foot per 150 square feet of ground, or seal the ground and add mechanical drying.…
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Ductwork Installation: What a Duct System Built to a Standard Requires
A duct system built to a standard starts with ACCA Manual J, S and D, is sealed with mastic rather than cloth duct tape, insulated to at least…
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Radon Mitigation System: How the Fan, Pipe and Vent Work Together
A radon mitigation system is a suction point, a sealed pipe, a continuously running fan and a roof vent. EPA’s action level, the fan’s watt draw and what…
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Dryer Vent Cleaning: The Venting Code and the Federal Fire Data
What IRC Section M1502 requires of a dryer exhaust duct, what the USFA and CPSC fire numbers actually show, and what a real dryer vent cleaning covers.
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Range Hood Ventilation: Ducting, Airflow, Makeup Air and the Code Minimums
A range hood only removes cooking pollutants if it is ducted outdoors. Here is what DOE, ENERGY STAR and the IRC set for airflow, duct routing, termination and…
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Bathroom Exhaust Fan: How to Size, Vent and Run One to Code Minimums
A bathroom exhaust fan needs at least 50 cfm intermittent or 20 cfm continuous, ducted outdoors. How to size, duct, terminate, control and verify one, from DOE, ENERGY…
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The HVAC Compliance Deadline Registry: Every Federal Rule, Date and Status
A maintained registry of federal HVAC requirements: refrigerant restrictions, efficiency standards, leak rules and the 25C credit, each with date, status, citation and a last-verified date. The 2026…
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Every HVAC Rule That Took Effect in 2026, With Dates
Four federal changes took effect during 2026: leak repair rules, VRF restrictions, new room air conditioner minimums, and an EPA rule that removed the R-410A installation cutoff.
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DOE Proposes Changing How It Sets Efficiency Standards
DOE proposed revising the process rule that governs how efficiency standards are justified. It shapes the pipeline of future HVAC standards without touching the ones already in the…
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Gas Furnaces Must Hit 95% AFUE From December 2028
Non-weatherized gas furnaces manufactured from December 18, 2028 must reach 95% AFUE, up from 80%. That effectively requires condensing equipment, and the venting conversion is the real problem.