They will go to 70% if unoccupied or if the airflow is invalid. What does your airflow trend look like?

 

They are occupied, and time is synced. Airflows are reading correctly but are reading above or below setpoint due to the damper staying at 70%. Fortunately these are the last jobs I used the canned non programmable junk on.

 

Does airflow ever drop out? Have a pic of the trend? might need to increase sample frequency in order to catch it.

 

Airflow doesn't drop out until the buildings go unoccupied at night. I've even tried scheduling 24/7 to take it out of the equation. It would make sense 9f it was a few VAVs under one AHU but it's over 200 VAVs under over a dozen AHUs across 2 buildings.

 

Do you have air source linkage setup to them? If so, when the air source mode goes to "Off" the damper is fixed to 70% regardless of the schedule or heating/cooling need in the controller. Except when a parallel fan is in heat mode, then the damper is closed. The master vav receives the air source mode and sends it to it's associated vav's, can check there.

What are the terminal modes of the VAV's?

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Do you have air source linkage setup to them? If so, when the air source mode goes to "Off" the damper is fixed to 70% regardless of the schedule or heating/cooling need in the controller. Except when a parallel fan is in heat mode, then the damper is closed. The master vav receives the air source mode and sends it to it's associated vav's, can check there.

What are the terminal modes of the VAV's?

View attachment 892951​

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Do you have air source linkage setup to them? If so, when the air source mode goes to "Off" the damper is fixed to 70% regardless of the schedule or heating/cooling need in the controller. Except when a parallel fan is in heat mode, then the damper is closed. The master vav receives the air source mode and sends it to it's associated vav's, can check there.

What are the terminal modes of the VAV's?

View attachment 892951​

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I'm not using linkage at these particular sites and never have. They've been running fine for years until now. Terminal modes currently are reheat, vent, or cooling.

 

You got me for a loss on this one. Been working with Carrier VAV's since the TSM days in the late 80's, then CID's, then VAV-B1's and with VAV-B2's. I got thousands+ of these out there, 500+ in one building alone. Never has an issue like this one. Looks like you may need to send thru your support channel on this.

As a side note, if the power was out for days as you state .... did you loose a configuration parameter setting in the controllers. Not sure the age of the OPN-B3's, but they do have a backup battery. It also too easy in i-Vu to select upload versus a download to the controller that has parameter differences.