#velocity

Tech Tips:

A few weeks ago, I was hired to consult on a multi-family new construction project. The building was already framed, and the ducts were roughed in. The owner of the building was concerned with the quality of the ductwork. He noticed that the HVAC company was not following the mechanical engineer's plans. This was my […]

The Ten Duct Commandments (Plus a Few More)

This article was written by my good friend, Neil Comparetto. He is one of the all-around best dudes in the industry and a guy who practices what he preaches on duct design. Thanks, Neil! These are some fundamentals for designing and installing duct systems that I’ve learned over the years. Included are links to […]

Reading CFM and Duct Velocity with a Testo 510i, the Smart Probe app and a Pitot Tube

Reading CFM and Duct Velocity In this video, we cover the basics of using the Testo 510i with a pitot tube to do a duct traverse and easily calculate Velocity in FPM and volume in CFM on a small 8″ duct. Using this method is handy because you can use the reliable, accurate and inexpensive […]

Measuring Airflow Podcasts w/ Jim Bergmann

In this two-part podcast series, Jim Bergmann covers measuring airflow in HVAC systems. He covers a wide range of airflow measurement instrumentation and readings. In the HVAC industry, many techs confuse static pressure for airflow. Although you need static pressure to have airflow, it is NOT airflow and can fluctuate rather wildly depending on the […]

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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/.

Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

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