#blower door

Tech Tips:

The Ups and Downs of High-Performance HVAC

This tech tip recaps the livestream by the same name, featuring HVAC School contributors Matt Bruner and Adam Mufich and special guests Michael Housh, Chris Hughes, and Dustin Cole. You can watch that livestream on our YouTube channel HERE. “High-performance HVAC” is a term we hear quite a bit these days, but it’s not easy […]

Solving Comfort and IAQ Issues in a Vintage Home: A Case Study

This tech tip is a recap of the Santa Fe Dehumidifiers and Comfort Dynamics, Inc. case study about a 1941 vintage home in Miami, FL. You can listen to the podcast about that case study by clicking the play button below, and you can read the case study at https://hvacrschool.com/case-study. Special thanks to Nikki Krueger […]

What is the Difference Between ACH & ACH50?

This photo is of a blower door test we performed at my own house using a Retrotec blower door. You will notice the 15-passenger van outside the window, which is a dead giveaway. A blower door is used to measure the tightness of a building and is often discussed in terms of an ACH50 number. […]

Blower Door Testing, Building Performance & More w/ Corbett Lunsford (Podcast)

In this podcast episode, Bryan talks to Corbett Lunsford about blower door testing and the coming building performance revolution. Building performance and HVAC have been becoming much more closely linked lately. So, it's a good idea for HVAC techs to learn a bit about building performance. In the HVAC world, we often see homes with […]

Bryan Brantley

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HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

Chris Hughes and Steve Rogers from The Energy Conservatory discuss TEC’s TrueFlow technology and its crucial role in predicting airflow issues in the sales process, particularly for heat pump retrofits. They explain how the TrueFlow app helps contractors accurately measure both static pressure and airflow in existing systems, enabling them to predict whether proposed equipment changes will work effectively. This is especially vital when considering the growing trend of replacing gas furnaces with heat pumps, as the airflow requirements can differ significantly.

The conversation delves into a detailed example of replacing an 80% efficient 48,000 BTU furnace with a heat pump. They demonstrate how the airflow requirement would nearly double from 652 CFM to 1,200 CFM, potentially causing the static pressure to quadruple due to Fan Law 2 principles. This dramatic increase could lead to significant performance issues if not properly addressed during the system design phase. The experts emphasize that using TrueFlow during the sales process allows contractors to identify potential problems and necessary modifications before installation rather than discovering issues during callbacks.

The discussion also covers the ideal workflow for system assessment and sales, starting with customer comfort evaluation and proper load calculations. It’s important to reduce loads through envelope improvements when possible, particularly in cold climates where heat pump retrofits are becoming more common. Proper system sizing often means going smaller rather than larger, contrary to common industry practices, and the worst HVAC systems are often found in expensive custom homes rather than tract housing.

Key Topics Covered:

TrueFlow technology and its role in system forecasting
Fan Law 2 and its impact on static pressure when changing airflow
Heat pump retrofit challenges and considerations
The importance of accurate load calculations
Dual fuel systems as a solution for cold climates
The relationship between airflow and static pressure
Sales process integration of technical measurements
Common issues with oversized equipment
The importance of envelope assessment
Methods for reducing system loads
Proper duct sizing and modification strategies
The role of proper filter sizing and selection
The benefits of flat-rate pricing for duct modifications
Training resources and support available for TrueFlow users

Check out TEC’s YouTube channel at https://www.youtube.com/@energyconservatory, and you can visit TEC’s website at https://energyconservatory.com/.

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