Guides
Pick a guide below to see the math worked out in full, not just the answer a calculator gives.
Reading the charts
Which PT Chart Do I Need? A Refrigerant Routing TableOne routing table to find the right refrigerant chart, plus which saturation point to read for superheat and which for subcooling.
What EPA's A2L Listing Means for R-454B and R-32What changed when EPA's SNAP program listed R-454B and R-32 as A2L, which of this site's five refrigerants that covers, and what it doesn't tell you.
Rules on the job
Refrigerant Leak Repair: Which EPA Rule Applies?Two separate EPA leak-repair rules cover refrigerant appliances: 40 CFR 82.157 for ozone-depleting refrigerants and the 2024 AIM Act rule for HFCs.
Recovery, Reclaim and Cylinders: The 2024 AIM Act ChecklistThe 15% virgin-HFC cap on reclaimed refrigerant, which sectors must service with reclaimed HFCs by 2029, and what to do with disposable cylinders.
R-22 and the HCFC Phase-Out: What's Left to KnowThe Clean Air Act's HCFC phase-out timeline through 2030, where R-22 sits on EPA's class II list, and the service, retrofit or replace decision.
EPA 608 study
EPA 608 Certification Types: Type I, II, III and UniversalWhat EPA Section 608's four certification types cover, how each test is built and graded, and the mail-in option for Type I.
What Each EPA 608 Test Covers: A Study Checklist by GroupA group-by-group study checklist for the EPA 608 core and technical questions, plus the areas this site's saved regulation text doesn't reach.