HVAC 101

9 snips

Apr 11, 2025

Matt welcomes Travis Brungardt, a licensed master mechanic and host of Prairie Sun & Timber, for a deep dive into HVAC fundamentals. They emphasize the necessity of accurate manual J load calculations over outdated methods. The duo discusses the benefits of rigid metal ducts for superior airflow and advises against unconditioned attic runs. They debate two-stage versus variable-speed systems and suggest ductless mini-splits for expansions. With practical tips on user education and maintenance access, they stress that a well-designed HVAC system enhances energy efficiency and indoor comfort.

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ADVICE

HVAC Planning

Don't just give HVAC contractors plans and expect a good design.
Provide clear direction and specifications to avoid first-cost optimization, which leads to suboptimal systems.

ADVICE

Manual J Importance

Treat mechanical system design with the same respect as structural design.
Get a proper Manual J load calculation to determine heating and cooling needs accurately.

ANECDOTE

Outdated Rule of Thumb

Matt Risinger recalls the outdated rule of thumb of 500 sq ft per ton of AC.
Travis Brungardt confirms this inaccuracy in modern building practices.

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Matt welcomes fellow Build Expert, Travis Brungardt, back to the studio for a “back to basics” conversation: HVAC 101, which includes foundational concepts, practical advice, and common mistakes in residential HVAC systems. Emphasizing the importance of proper planning, they stress starting with accurate manual J load calculations to avoid outdated “rules of thumb” like sizing based solely on square footage.

Matt & Travis also break down the crucial roles of manuals D (duct design), S (equipment selection), and T (terminations). Both champion rigid metal ductwork for optimal airflow, using minimal flex duct only at final connections to reduce noise. Also, they warn against unconditioned attic duct runs and advocate for dedicated return ducts in each major room to maintain balanced airflow and comfort. The conversation explores the pros and cons of two-stage and variable-speed systems, promotes ductless mini-splits for additions, and strongly advises against zone damper systems due to reliability issues.

They also highlight the importance of user education: set thermostats and forget them, avoid "fan on" mode, and design systems for future maintenance access. Matt and Travis remind builders that a well-designed and properly installed HVAC system not only improves energy efficiency but also delivers lasting comfort and better indoor air quality.

To see a practical application of the strategies outlined in today’s episode, check out Prairie Sun & Timber, a Build Original® series hosted by Travis.

Thank you to episode sponsors Pella & Huber! Learn more at pella.com and huberwood.com.

Find Travis on the Web:

Build Original Series®: Prairie Sun & Timber
Travis’ Build Show Videos: https://buildshownetwork.com/go/travisbrungardt
Travis’ Instagram: @catalystbuilt
Travis’ Website: https://www.catalystbuilt.com/

Find Matt and The Build Show on the web:

Build Show Videos: https://buildshownetwork.com/go/mattrisinger
Instagram: @risingerbuild and @thebuildshow
YouTube channel: https://www.youtube.com/@buildshow
Websites: https://risingerbuild.com/ & https://buildshownetwork.com/

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