York VAV Air Handlers | HVAC ZoningYork VAV Air Handlers | HVAC Zoning - This York air handling unit serves several VAV boxes and runs on a static pressure control set point determined by a DDC program. This program has a static pressure control setpoint and sends a signal to the variable frequency drive to speed up or slow down the blower to maintain the proper static pressure control setpoint. When the VAV boxes need more air the drive speeds the air handler blower up. When the VAV boxes need little the drive slows the blower down. The VAV boxes are controlled by a thermostat in their respective zones.

York VAV Air Handlers | HVAC Zoning

When the space is too warm the thermostat sends a signal to the controller. The controller gets this input from the thermostat and determines that more air flow is needed. It opens the damper more using more air supplied by the air handler blower. The static pressure transducer reads this loss of static pressure and sends a signal to the DDC controller. The DDC controller sees that the duct static pressure is below the set point and sends an analog signal to the variable frequency drive.

This analog signal tells the variable frequency drive to speed up to make up for the loss in duct static pressure as determined by the static pressure transducer. This same scenario is reproduced over and over again during the occupied hours that the building is open. During the unoccupied hours, which is programmed into the building automation system, the entire system shuts down unless manually overridden by an occupant such as a worker working late to finish a project. The system will automatically end the override after a set amount of hours and return the system to normal.

High Performance HVAC

York VAV Air Handlers | HVAC Zoning

To learn more about heating systems and HVAC use this resource.

See the About the Author page for information about the author of this article.

Share your HVAC Photos or ask a question about your HVAC System by uploading a photo of it.

Photo Uploads
Enter your name so we can credit you
If you have a website enter your website URL for additional credit
If you want to include a description then do so here.
Drop a file here or click to upload Choose File
Maximum upload size: 33.55MB
jpe, jpeg, jpg, gif, png, bmp, docx, doc, txt and PDF files allowed to be uploaded. Limit 15 files total and 100 mb/s max size.