Intro to Pneumatic Controls w/ Jim Loring

HVAC School - For Techs, By Techs

Bryan Orr

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

4.8 • 985 Ratings

🗓️ 18 January 2018

⏱️ 44 minutes

🔗️ Recording | iTunes | RSS

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Summary

In today's podcast episode, Bryan talks to west-coast commercial tech Jim Loring about pneumatic controls and variable air volume (VAV) systems.

People sometimes confuse pneumatics and hydraulics. Hydraulics use liquid to provide pressure; conversely, pneumatics use air to provide pressure. Pneumatic controls use a bit more energy than other controls, but they are less costly all around. Nowadays, direct digital controls (DDCs) provide greater energy savings than pneumatics. However, pneumatic controls were a precursor to the DDC technologies we use on actuators today, and they are still a prevalent technology.

The air compressor is a critical component of pneumatic controls. That is because pneumatic controls require clean, dry air. Air compressors have an auto-drain and auto-dryer to help purify the air for peak performance. However, while air compressors are basic, their maintenance practices are often overlooked.

Variable air volume (VAV) units vary airflow throughout the building via zones. Each zone has a damper and a thermostat. The thermostats control the dampers, which control airflow to the zone and move via actuators. In a pneumatic control system, the air pressure release or gain at the thermostat moves the dampers. Thermostats also have to bleed off some of that air via direct or reverse-acting controls. Bypasses help regulate static pressure when dampers close.

Thermostats can help modulate the dampers; they don't merely open and close. The modulation occurs within a certain pressure range on a VAV system. (For example, 8 PSI would close the damper while 13 PSI would leave the damper wide open.) In addition to damper modulation, velocity controllers help control the air velocity based on signals from the thermostat.

Jim also covers:

Common air compressor problems
Pressure-reducing valves (PRV)
Restrictor tees
Direct-acting vs. reverse-acting controls
Heating and cooling in VAV systems
Damper position

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Transcript

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0:00.0	The following podcast is made possible by our sponsors carrier, rector seal, and Mitsubishi
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0:21.0	Discover how Zoomlock can help you be more efficient and productive.
0:25.3	Visit zoomlock.com for more information. Allow me to introduce the guy who actually says actually after every word actually
0:42.0	Brian or this is word actually, Brian, or.
0:44.6	This is actually the H.P.
0:47.0	School podcast.
0:48.4	Everybody has their verbal ticks, the words that they say over and over again, especially when they get nervous, and
0:54.3	mine is the word actually.
0:55.3	I actually switch between vocal ticks at different times.
0:59.9	I've learned mostly to stop saying, all the time but anyway this is the
1:04.3	HVAC school podcast I also say anyway a lot this is the HVAC school podcast I am Brian or
1:08.8	and this podcast is the podcast that reminds you of all the things that you might have forgotten about the HVACR industry as well as remind you
1:16.0	to some things that you might have forgotten to know in the first place and I want to
1:19.7	remind you of something quickly before we move on in this podcast and that is that this
1:24.1	podcast is a support to the industry it is not a replacement for anything that
1:28.0	existed before so this does not replace trade school it does not replace
1:31.9	apprenticeships it does not replace apprenticeships. It does not replace
1:33.2	hands-on training. It is simply a supplement to what a lot of technicians are
1:39.0	already doing and what a lot of Trade Schools are already doing, which is the
	...

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