Why a Thicker HVAC Filter Can Have Less Pressure Drop Than a One-Inch Filter - Part 1

In this episode of HVAC Know It All, host Gary McCreadie talks with Chris Howells, Senior Training & Development Manager at AprilAire, about applying indoor air quality solutions during shoulder seasons and making filtration part of a complete HVAC approach. They cover humidity concerns, filter selection, MERV ratings, pressure drop, airflow, and ways technicians can explain system performance to homeowners.

Chris draws on his work educating contractors about filtration and indoor air quality. He explains why increasingly sealed homes and modern variable-speed equipment require technicians to assess the full system, including duct design, filter surface area, and delivered airflow, before recommending higher-efficiency filtration.

Key Takeaways How to use shoulder-season humidity and comfort concerns to start an ethical indoor air quality conversation.

Why indoor air quality solutions should address human health and comfort rather than focus on selling products.

The relationship between filter MERV rating, pressure drop, surface area, and delivered airflow.

How deeper media filters can provide more filtration surface area without equating filter depth with restriction.

Why variable-speed ECM motors can be more affected by restrictive filters than older single-stage PSC motors.

How static-pressure measurements and visual evidence can help homeowners understand filtration-related system issues.

Key Timestamps

00:00 – Factory Direct Filters Ad

00:42 – Episode overview and Guest introduction

04:14 – Providing indoor air quality solutions during shoulder season