Measuring Airflow For Techs

HVAC School - For Techs, By Techs

Bryan Orr

Training, Careers, Airconditioning, Self-improvement, Hvac, Business, Education, Refrigeration, Heating, Ac, Apprenticeship

4.8 • 985 Ratings

🗓️ 8 March 2018

⏱️ 42 minutes

🔗️ Recording | iTunes | RSS

🧾️ Download transcript

Summary

In this discussion with Bill Spohn from TruTechtools.com, we cover the practical steps and tools for YOU to start measuring airflow today, if not sooner.

There are several ways to measure airflow; when measuring airflow, start with the "why" rather than the "how." Understand what the goal of the airflow is before you begin taking measurements in random places.

You can take a bulk measurement at a return, but you have to be prudent to avoid human error. The best way to avoid error is to use a TrueFlow grid, which replaces the filter and uses a pitot array to measure airflow in the return. Another relatively easy way to get a bulk measurement is to use a flow hood. However, it can be easy to mess up the positioning of a flow hood (or not have enough room for it).

Many techs misuse tools like vane anemometers and collect poor data. Vane anemometers can gather information throughout the duct (mini vane) or over the supply or return (larger vane). You want to pick up the micro-transitions in air velocity to get quality data; you can use either point or traverse measurements and average those readings to come up with your average CFM.

We can take measurements INSIDE the duct with pitot tubes (although we have our reservations about using those), hot wire anemometers, and mini vane anemometers. In-duct measurements require multiple measurements and consistency during testing.

A common system airflow measurement doesn't measure CFM at all; that measurement would be static pressure. However, you need to have the correct tables and understand all of the load requirements to measure static pressure effectively.

Bill and Bryan also discuss:

Pitot tubes vs. static pressure probes
Air movement metaphors
Point vs. traverse measurements
Static pressure drop
Total system airflow setup
Ventilation airflow

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Transcript

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0:20.0	This episode of the HVAC School Podcast is brought to you by Carrier, Mitsub Comfort and Rector Seal. And these three companies, they honestly make HVAC school what it is.
0:27.0	You may have seen recently, we launched a new HVAC school forum which you can find by going to HVAC School Forum.
0:34.8	Very easy. You can sign up there.
0:36.8	You've seen recently, we've made some new calculators on HVACR School.
0:40.3	com and some new resources, and all of that is made possible by the
0:43.9	sponsors by these companies who partnered with HVAC school frankly when we did not
0:48.8	have the audience that we have today we didn't even have the the of people, but they partnered with us. They make
0:54.1	this possible. I really appreciate Carrier, Mitsubishi, and Rector Seal for doing all that they do
1:00.0	for industry education. Meet ZoomL on, the 10 second flame-free refrigerant fitting from Parker.
1:06.0	Reduce labor costs by 60% with no braising, no flame, and no fire spotter.
1:11.0	Discover how Zoomlock can help you be more efficient and productive.
1:15.4	Visit zoomlock.com for more information. The man who still cringes every time he sees equipment flying with a crane, Brian Orr.
1:29.0	Hey, hey, hey, what do you say?
1:31.0	This is the HVac school podcast and I am Brian Orr. I host this thing I guess I guess that's what I'm doing. You can
1:38.0	just imagine that I'm an annoying apprentice who's writing he's riding next to you in the van and spouting all sorts of annoying
1:47.2	apprenticesy things at you and asking you too many questions. That's me. That's me.
1:51.8	And yes, it is true that I was just talking to my brother Nathan about this.
1:56.3	Some of you know Nathan from the Facebook group.
1:58.3	He's kind of a different guy, to say the least.
2:02.4	Anyway, my brother-in-law and him work closely together in my
2:05.0	commercial refrigeration commercial HVax side the big stuff the big box stuff
2:10.1	the grocery stores you walk around and you get lost, you know, those sorts of places.
	...

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