Overview
HVAC code moved more in the last cycle than it had in a while, and the A2L refrigerant provisions alone changed what is allowed in equipment rooms and how you handle charge. If your working knowledge of the IMC is a few years old, some of it is now wrong in ways that matter.
This is the IMC condensed to what gets looked up on install and service work, covering the 2021 and 2024 editions side by side so you can work under either.
What's inside
- Ventilation rates, residential and commercial
- Duct sizing and material requirements
- Combustion air requirements
- Appliance clearances and venting
- Refrigerant piping references
- IMC 2021 and 2024 editions
- Excel and PDF formats
Where the 2024 edition changes your install
A2L refrigerants being permitted is the headline, and it carries through into equipment room provisions and leak detection. Clothes dryer exhaust terminal placement moved. Plenum material restrictions tightened. Condensate discharge now wants identification markings that most techs are not yet in the habit of applying.
None of those are difficult. They are all easy to miss, because they are changes to things you have been doing the same way for years. The full rundown of what moved is worth ten minutes before your next changeout.
Who it's for
HVAC installers and service techs working residential and light commercial who need combustion air, clearance, and venting answers on site rather than back at the shop.
Works best with
Code tells you what the install has to be. Pricing tells you what it is worth. Keep both on the tablet.
- HVAC Flat Rate Price Book, 190 services priced, including the install work this guide governs
See the full system on our How It All Works page.
Why buy this one
Organised around install and service decisions rather than chapter order, and updated for the 2024 changes that quietly invalidated a few habits.
- Built for the truck. Clearance and combustion air answers without unrolling anything.
- Two formats. Excel for searching, PDF for printing and for the days your phone is dead.
- One payment. No subscription and no renewal to forget about.
- Answered by the builder. Message on Etsy and you get a reply from the person who made it.
What it is not
It is not the IMC and carries no authority. Your AHJ decides. Manufacturer installation instructions also govern in places where they are more restrictive than code, and this guide does not replace reading them. Refrigerant handling is additionally governed by EPA rules that sit outside the mechanical code entirely.