Outdoor Air & Ventilation Strategies with John Semmelhack, Ty Branaman, Tim DeStasio, & Bryan Orr

How much outdoor air does your home actually need — and what's the right strategy to bring it in without wrecking comfort or humidity control? In this HVAC School livestream, Bryan Orr sits down with John Semmelhack, Ty Branaman, and Tim DeStasio for a deep dive into residential ventilation strategies that actually work in the field. The crew covers the three core approaches to managing indoor air — circulation, extraction, and dilution with outdoor air — and breaks down when each one makes sense. You'll hear real talk on ERV vs. exhaust-only systems, why "outdoor air" isn't always "fresh air," and how climate (humid vs. dry) completely changes your ventilation design decisions. Topics covered in this episode include: Why ventilation (the "V" in HVAC) is the most overlooked part of the system ASHRAE 62.2 ventilation requirements and common misunderstandings Blower door testing and air infiltration rates in tight, high-performance homes Moisture and humidity control when introducing outdoor air ERV/HRV systems, exhaust-only ventilation, and balanced ventilation strategies Dehumidifiers and how they pair with mechanical ventilation Range hoods and combustion safety considerations Crawl space and duct design impacts on indoor air quality Filtration, MERV ratings, and pollutant control Real-world retrofit vs. new construction ventilation approaches Whether you're designing new builds, retrofitting older homes, or just trying to wrap your head around outdoor air strategies, this conversation with John Semmelhack, Ty Branaman, Tim DeStasio, and Bryan Orr is packed with practical, real-world insight you can apply on your next call.