Next-Gen Filtration - Pressure Drop, MERV 16, and Bypass Prevention w/ Chris Howells · HVAC School - For Techs, By Techs summary

Key takeaways

A thicker filter is primarily about the surface area and face velocity, not just the media depth.
Using the full face of the filter and proper sealing of the media minimizes bypass air, improving system efficiency and protecting equipment.
Measuring pressure drop accurately with the right tools and referencing manufacturer data is essential for system optimization.
High MERV ratings do not automatically mean high restriction; media design and system conditions influence pressure drop.
Proper cabinet design, including sealed edges and correct sizing based on airflow, helps prevent bypass and maintains system performance.
Technicians should approach indoor air quality discussions with simple, natural questions to engage homeowners effectively.
Ongoing education and understanding system design principles are crucial for selecting the right filters and improving system performance.
Designing systems with low static pressure, especially with modern ECM blowers, enhances longevity and efficiency.

Summary

Introduction and Episode Overview

Bryan Orr introduces the episode, noting that he's speaking with Chris Howells from AprilAire. They plan to explore the performance of filtration systems, addressing misconceptions about filter thickness and emphasizing the importance of surface area, face velocity, and pressure drop. Bryan admits that his own contracting business is considering using more AprilAire filters, framing the discussion as both educational and practical for field application. Chris shares his background, highlighting nearly 30 years in HVAC, with 15 years as a technician, and his current role leading training at AprilAire.

Understanding Filter Thickness and Surface Area

The hosts discuss common misconceptions about thicker filters, clarifying that thickness often refers to media depth but that surface area and face velocity are more critical factors in filtration performance. Chris explains that a deeper media doesn't automatically mean more restrictive airflow; instead, how the media is loaded and the system design matter more. They emphasize the importance of using the full face of the filter to maximize performance and reduce uneven loading, which can cause bypass and inefficient operation. Proper cabinet design and seal quality are vital to ensure air is forced through the media and not around it, thus protecting equipment and optimizing airflow.

Filter Media and Pressure Drop

The conversation shifts to the technical aspects of media construction, including how to measure pressure drop correctly with proper tools like dual-port manometers and static pressure probes. Chris stresses using manufacturer data at specific face velocities (around 500 feet per minute) to evaluate filter performance. They discuss that higher MERV ratings do not necessarily mean higher restriction, especially when comparing filters. A common mistake is to assume deeper or higher-rated filters always create more resistance, but the media design and system conditions significantly influence this.

Design and Bypass Prevention

Chris describes how AprilAire cabinets are designed to prevent bypass air through features like top and bottom rails and self-sealing media overhangs. They highlight that full-face contact and proper sealing reduce static losses and prevent unfiltered air from bypassing. The hosts also discuss how to size media cabinets based on actual CFM and face velocity rather than just dimensions. They point out that good design results in lower static pressure and longer filter life, contributing to better system performance and longer-lasting equipment.

Effective Communication and Continuous Learning

Bryan and Chris talk about how technicians can start meaningful indoor air quality conversations with homeowners, focusing on improving air quality and system performance rather than just selling filters. Asking simple questions like, 'Would you like to improve the air quality in your home?' can initiate these discussions. Chris encourages ongoing education, recommending resources such as AprilAirePartners.com and the AprilAire Academy. He emphasizes never stopping learning and understanding the 'why' behind best practices in filtration, system design, and building science to better serve customers and improve system longevity.

Show notes

In this episode of the HVAC School Podcast, Bryan sits down with Chris Howells, senior training manager at AprilAire, to talk about what really makes a filtration system perform. Chris has nearly thirty years in the industry, including fifteen as a technician, and brings a field-first perspective on why filtration is more than just "a filter." Bryan also admits up front that his own contracting company is looking to put more high-efficiency filters into the field, so this conversation doubles as a practical learning session.

The discussion starts with a common misconception: that a "thicker" filter is simply a filter with thicker media. Chris explains that what matters is surface area, face velocity, and pressure drop, not the width of the cabinet. They cover why using the full face of the filter is one of the easiest wins, how a poorly designed return can load just one section of the media, and why a high MERV rating does not automatically mean high resistance. Cabinet design, media construction, and overall system design all play a role, and modern ECM blowers make low static pressure more important than ever.

From there, the conversation turns to bypass air and measurement. Chris describes how AprilAire's cabinets use top and bottom rails and a self-seal media overhang to force air through the filter, backed by a 10-year clean coil guarantee. He and Bryan stress using the right tools, including a dual-port manometer and a proper static pressure probe, and checking pre-filter and post-filter pressure drop against manufacturer performance data at around 500 feet per minute. Chris also debunks the idea that deeper media is always more restrictive, pointing out that a typical retail one-inch pleated filter can raise pressure drop dramatically compared with a basic fiberglass filter.

The final stretch is about communication and growth. Chris and Bryan share simple, natural questions technicians can use to start air quality conversations without sounding like a sales pitch, and they encourage listeners to stay curious and keep asking "why." Chris closes with resources for learning more, including AprilAirPartners.com and the AprilAire Academy, and mentions that the Santa Fe and UltraAire product lines are now part of the AprilAire family.

Topics Covered

Why "thicker" filters are really about surface area, face velocity, and pressure drop
Using the full face of the filter and avoiding uneven loading
How filters affect blower performance, system capacity, and equipment protection
Why filtration is a high-value upgrade compared with bulbs and modules
AprilAire's new high-efficiency product line and its three-layer media design
Reducing bypass air with rail design, self-sealing media, and the 10-year clean coil guarantee
Measuring static pressure correctly and using manufacturer pressure drop charts
Sizing media cabinets by CFM and face velocity instead of what fits under the air handler
Common myths about MERV ratings and restriction
Conversation starters that help technicians talk about indoor air quality
How to learn more through AprilAirePartners.com, the AprilAire Academy, and local distributors

This episode contains embedded sponsor messages from Refrigeration Technologies, Carrier, Copeland, Santa Fe Dehumidifiers, and TruTech Tools.

Resources

Purchase your tickets or learn more about the 8th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

Next-Gen Filtration - Pressure Drop, MERV 16, and Bypass Prevention w/ Chris Howells