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What is an Air Flow Hood?

HVAC systems are far from a “one size fits all” type of technology. The size of a home, its layout, the area’s expected year-round weather, and the needs of its residents all come into play when a technician selects the right pieces for a home’s HVAC system. Should you need a new HVAC system, a technician will use several different tests, like an air flow hood, to get a whole-house picture of airflow throughout the house. 

In homes with existing HVAC systems, a technician will want to assess the airflow throughout the home to see what might be improved. When it comes to tests like these, an air flow hood is integral to seeing how an HVAC system is working in a home and where adjustments might need to be made. Just as technicians work together during installations, maintenance, and repair, so too does their equipment. In this article we’ll be exploring one single piece of equipment, the air flow hood, and see not only what it does but how it fits the process of a whole home diagnostic. 


What is an Air Flow Hood?

At first glance, an air flow hood is a large plastic square with controls attached to a taut, flexible fabric “tent” that sticks out several feet. When used, it is placed over a vent inside a home to measure the air flow that comes out into the room. It can attach to floor and ceiling vents depending on how the home was designed. When used correctly and in tandem with other diagnostic tools, the air flow hood shows technicians if the air flow in a home is “balanced,” meaning that no single room is receiving too little or too much air. The information provided by an air flow hood can help to prevent rooms in a home that “stay hot” or get “far too cold” for residents’ comfort. 


Providing Hard Data

The information provided by an air flow hood may not seem intuitive at first. David Richardson of speaks of his first trials in the article, “Duct Dynasty: Lessons from an Air Flow Hood”. As a technician and installer himself, he took pride in what he considered to be very well balanced HVAC systems until the use of an air flow hood informed him otherwise. The intuition that had been leading him could not stand up to the hard data provided by the diagnostic and forced his team to take a new approach to how they installed HVAC systems. 

When he integrated this tool into his system testing, Richardson realized, “Our designs weren’t doing what we assumed they were, and our customers weren’t getting what we’d promised and sold them.” Bringing in a new level of testing technology with the air flow hood taught Richardson and his team a valuable lesson and helped them to greatly improve their installation practices and, in turn, offer their customers even better air comfort.

SEE ALSO: Why Does My HVAC System Blow Too Little Air?


Diagnostics in Demand

Gathering accurate information about the air in a home cannot be done with a single tool. Although an air flow hood can offer a lot of useful information, it cannot be relied on as a single point from which an HVAC service team can work. In the article, “How to Use an Air Balance Hood” they recommend that a hood is used in tandem with the following measurement devices:


  • Manometer – This measures the pressure of air flow in the HVAC system.
  • Anemometer – An anemometer measures the speed of the air as it moves.
  • Thermometer – A familiar tool, thermometers measure temperature. 
  • Psychrometer – These are used to measure the humidity levels in air. 


All of these tools, together with the use of an air flow hood, paint an accurate picture for HVAC technicians so they can tell where a home’s HVAC system needs improvement or adjustment. These tools can be used during repair, installation, or during maintenance when homeowners notice changes in their home’s air comfort levels. Just like working together with other people to gather information, find problems, and bring the combined skills and knowledge of everyone involved together to create a solution, so too must these tools be used in concert to understand how a home’s airflow is functioning and how it might be made better. 


Call the Experts

If you feel like your home’s air comfort could be improved, or if you suffer with problems like rooms that are too hot/cold, poor humidity control, or loud vents, please get in contact with your local, licensed HVAC service provider. Their technicians will be able to use tools like an air flow hood to spot any issues with your existing HVAC system and make suggestions for improvements. Although it can be hard to admit misconceptions and move towards change, the tools of the HVAC trade all serve to bring your life into balance. 

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