To watch a video version of this podcast, click here: https://youtu.be/-Tsv9suvZwc In this episode, Reuben Saltzman and Tessa Murry discuss kitchen hood fans and exhaust ventilation, focusing on CFM, hood design, ductwork, makeup air, and combustion safety. They explore common ventilation problems found during inspections, explain how excessive exhaust can affect homes, and discuss Minnesota’s makeup-air requirements. The episode also introduces AI-powered calculators to help homeowners determine fan and makeup-air requirements, along with practical tips for improving kitchen ventilation and indoor air quality. For Reuben's calculator on the Maximum Exhaust Fan Rating Without Makeup Air, go to https://docs.google.com/spreadsheets/d/1VT9XTGvmk7RVMfh4D-_iveF8LyNhYBelOeqSKS6vPds/edit?usp=sharing. For the Makeup Air Calculator with Opening Sizing and Home Age, go to https://docs.google.com/spreadsheets/d/1b_899bkGIt8WNK8H6KwrErB9_YO80jAYb2zVy5dIEDk/edit?usp=sharing Here’s the link to Inspector Empire Builder: https://www.iebcoaching.com/events Takeaways Effective kitchen ventilation depends on proper hood design, placement, ductwork, and capture efficiency—not just CFM. Larger fans can increase energy use and may cause depressurization or backdrafting in homes with combustion appliances. Common inspection issues include blocked dampers, disconnected ducts, restrictive ductwork, and improperly configured microwave hoods. Minnesota makeup-air requirements vary based on fan size, home characteristics, and combustion appliances. AI-powered calculators can help homeowners and inspectors determine appropriate fan, makeup-air, and duct-sizing requirements. Proper ventilation helps improve indoor air quality, including when using electric cooking appliances. Homeowners should use exhaust fans while cooking, check exterior dampers, use back burners, and choose properly designed, quieter hoods. The key takeaway: Good kitchen ventilation is about effective capture and proper system design—not simply installing the largest fan. Chapters 00:00 Introduction and AI Report Reviewer Update 02:43 Sponsor Spotlight: Inspector Empire Builder and Rapid Gain Training 04:39 Introducing the Kitchen Hood Fan Topic 05:35 Why Kitchen Ventilation Matters for Indoor Air Quality 07:14 CFM vs. Hood Design and Capture Efficiency 08:11 Why Hood Shape and Placement Matter 10:28 Typical Kitchen Hood CFM Ratings 11:40 Oversized Fans and the Energy Penalty 12:15 Makeup Air for High-CFM Exhaust Fans 13:13 How Ductwork Affects Actual CFM 14:42 Duct Restrictions, Exterior Terminals, and Airflow Problems 15:10 Stuck Dampers and Common Inspection Findings 17:20 Microwave Hood Fans and Recirculating Systems 19:17 How Many Homes Have Proper Exterior Kitchen Ventilation? 20:05 Indoor Air Quality, Cooking Pollutants, and Code Requirements 21:03 Gas Cooking, Carbon Monoxide, and Ventilation 22:15 Minnesota Ventilation Requirements 22:58 The Truth About the 300 CFM Makeup-Air Rule 23:28 National Code Requirements for Makeup Air 26:14 Why One-Size-Fits-All Makeup-Air Rules Can Be Problematic 27:39 Backdrafting Risks in Tight Homes 28:59 Reuben's New AI-Powered Maximum CFM Calculator 30:39 Factors Used in the Minnesota CFM Calculation 32:50 When a 300 CFM Fan Requires a Calculation 33:31 Calculating Makeup-Air Requirements and Duct Size 34:25 AI-Powered Makeup-Air Calculator 35:23 Making Complex Code Calculations Easier 37:03 Minnesota Code Exceptions and Combustion Safety Testing 38:22 Worst-Case Depressurization Testing 39:06 When Makeup Air May Be Avoided 40:31 Practical Kitchen Ventilation Tips 41:13 Using Back Burners and Choosing a Quiet Hood 41:54 Microwave Vents vs. Proper Capture Hoods 44:30 Why Capture Efficiency Matters More Than CFM Alone 45:25 The Difference an Exhaust Fan Makes in an Airtight Home 47:49 Closing Thoughts and Listener Feedback