HVAC Tech Tip - Controlling a VAV box with the only Pneumatic controller you will ever need.

In this edition of Tim's Tech Tips, Tim's going to show you how to control a VAV box with a Pneumatic Controller. Controllers like the KMC CSC 3000 are reset volume controllers that are
designed for use on heating or cooling systems with
(normally open or normally closed) VAV terminal
units and (direct or reverse acting) thermostats.
They are sub-master air velocity controllers. Each is
equipped with separate adjustment knobs for minimum
and maximum airflow setpoints. Models are
available with various reset start points. A master
controller, typically a room thermostat, resets the
CSC-3000 between the minimum and maximum
velocity setpoints.
The universal design of the CSC-3000 series is intended
for new or replacement applications that call
for direct or reverse acting reset on normally open or on normally open or normally closed VAV terminal units , which makes them very flexiable. You only need one for your truck and you will be prepared for any vav reset controller replacement.

[robertcastleberry]

Tim, been awhile hope you see this. Thanks to you and your classes I took 10 years ago ive advanced my career And im inline to be the Big boss now. I became a lead tech in my field and quickly moved up in my feild of work. I now have my own team now and Ive also have learned all the new controls systems. However there are still so many pneumatic buildings out there the demand is still out there for this knowledge for all you beginners. Please watch all Tims classes. It will help you alot. It will help you to know this technology before learning electronic devices. You will understand more how they function. Tim is no longer with stromquist and has moved on because his classes were canceled. However he is still in the business and i hope he is successful. Best wishes to all.

[theNdrexel]

8 years later and still the best video I've come across in terms of explanation and demonstration. Thank you for the resource.

[DynaGlyde]

Thank you for this video on the kreuter.

There's much to learn about commercial HVAC, especially when you're never done it.

[leonardpopper]

Great very hands on video. Just want to mention one thing you said it backwards in the beginning of the video. Air pressure going in to the censor is velocity pressure and port at the back measures static pressure. Difference between those two is true velocity pressure and not total pressure. Total pressure is velocity pressure plus static pressure which is opposite of true velocity pressure. True velocity pressure = differential pressure which we all want to measure. Refrigeration & air conditioning 6th edition unit 37 air distribution and balance - figure 37-11 for reference.

[ACHVACTAB]

Pretty good display. Points to note: Use / put a gauge in the Actuator line to see an adjustment / reaction in PSI
This allows you to work fast and determine if you have control of the damper. Also, the DP taken at the probes is a rough ballpark of your Cfm, a flowhood at the outlets is the best/simply determination of Cfm. 2. The main control air is best from
15 - 20 PSI or it gats sluggish or non-responsive. Bobby: Your question is confusing. The controller is the same regardless of
size. Size matters as related to the flow you want and the static / velocities your system can handle. The newer DDC electronic
controller's do get set / programmed for inlet size since it usually allows actual Cfm viewing. Happy for questions.

[michaelpajewski]

Great video, thank you for doing a great job explaining this. You just made my job easier when I’m only making some adjustments on these maybe once a year if that.

[geraldschilli]

Good video. Looks like several techs have a lot of questions. Wish more techs would see this. I was told by a counter man at a parts supplier that some “rookie” techs would come in & purchase the t-stat, velocity controller, damper actuator & valve actuator because they didn’t know how to troubleshoot the system. By replacing all the parts, they were bound to get lucky & somehow get the zone working again. Never mind that they probably didn’t know how to calibrate and or adjust & fine tune the controls. These type of techs should not be working in this industry!!!

[ronerwin]

Thanks Tim, awesome video, I was having problems with reverse acting stat on system, didn't know that controls knobs had to be used in reversed as well, home run :-)

[roqueherrera]

THANK U!!!! Best physical presentation I have seen!

[grangus]

Thank you for your video can you please recommend any books in pneumatic thermostat, VAV boxes and mix boxes i got this new job in a old building full of pneumatic

[diegosti]

Work with those animals everyday! Branch is always used for damper and for a cooling vav with hot water valve you need to T the t from t stat to the actuator valve and end in the T of controller.

[nickmiller]

please make a video of Siemens Rc 195 receiver controller calibration, thanks

[gearhead]

Thanks for your great videos Tim, One question; at 5:17, I hear you say D.A. Stat with a N.O. box, that would mean that as the temperature increase the air signal to the n.o. box would also increase which would close the box (air flow ) for cooling. Am I missing something?

[MiguelDecase-xh]

I have a question direct vs reverse acting seems similar to. How do you identify the difference,

[Dan]

Does a R/A NO vav box also have the adjustments reversed?

[cristianhernandez-hnwp]

make a video explaining how to control 2 different temperatures

[mikeyangel]

Hi, Mr Tim I'm working for a commercial real estate company and i really need
to learn how to troubleshoot and repair VAV systems, can you recommend a
company or materials to edify myself, thx.

[DotNetProductions]

Here's where Ya got me confused. what is the relationship between the Actuator and the Position of the damper? Normally Open could be Actuator fully extended or it could be fully closed depending on the mounting of the actuator and direction of travel. Working on a Dual Deck system and Direct Acting Thermostat. Using the controller position NO/NC. One Actuator will be Full extended and the Damper be Full closed or Full Open. The the same is true pf the Hot Deck the actuator could be fully extended and the Damper be fully open or fully closed. So having the controller set to Normally Open or NOrmally closed works how? The video even when played on a 65 inch TV I wasn't able to see the position of the Actuator weather you had it set to NO and was the actuator fully extended or NC and the Actuator fully extended.

[DotNetProductions]

OK, let me know if I'm understanding this correctly
Direct Acting Normally Closed = Damper closed or at minimum position when pressure is 7.5psi or lower?
SO on a dual Deck system. Having a NC for the hot side also. Using the same DA thermostat when there no pressure or low pressure. You're saying this controller will work to increase the Damper opening as the Thermostat pressure drops below 7.5 psi? Wouldn't that actually not allow the damper to open?
Both sides are using the same DA thermostat and different controllers and air supplies. SO during the summer there is no pressure to Hot Controller so the Normally Closed state is by default with no pressure.


How does the controller know that the hot side needs low pressure from the thermostat to open and the cold side know that the cold side needs more pressure to open. Seems to me one side would need to be set to NC and the other to NO even though they are both Normally closed when there is no pressure to the system. Am I wrong what am I missing?

[tymetabooker]

If my VAV is calling for an 7" contoller can I use an 8" contoller instead, with proper adjustments of high or low stat deltas? I am wondering if the size only has to do with how the controller is adjusted?!!!