What is the reference pressure and the static pressure multiplier?

Issue:

What is the reference pressure and the static pressure multiplier?

Resolution:

The VariTrac CCPIII measures the static pressure reference during calibration.
The static pressure reference is the pressure generated in the following situation:
- fan on
- bypass closed
- all VAVs at their maximum airflow

The static pressure multiplier can range from 1.0 to 2.0.
The static pressure setpoint = multiplier times reference pressure.
The bypass damper is modulated to control to this pressure.

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If you change the static pressure multiplier, the CCP must go through calibration before the new static pressure setpoint will take effect.

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The Tracker book, BMTK-SVU01C-EN, page 63 and 64 says that you can change the Static Pressure Setpoint from the Tracker display.
This is not correct.
You cannot change the Static Pressure Setpoint directly.
You cannot change it from the Tracker display or the CCP display or the Tracker software or the CCP software.
The only way to change the Static Pressure Setpoint is by changing the Static Pressure Setpoint Multiplier.
Or have the CCP go through the calibration process again to the change the Static Pressure Reference.

Notes:

We occasionally see the Reference Static Pressure value on Status tab 2 displays "???" instead of the actual static sensor value determined during a Varitrac calibration cycle. The calculated AHU static pressure displays correctly as does the Static Pressure Setpoint and the bypass damper appears to maintains correct static.

Changes:

 

Other Question/Problem/Cause Statements:

• What is the reference pressure and the static pressure multiplier
• In Setup tab 1 of the VariTrac III CCP, we were able to change the static pressure setpoint multiplier but it does not change the setpoint. WHY?
• How does the CCP calculate its duct static pressure setpoint?
• Can I change the static pressure setpoint?

Facts:

• VariTrac III Central Control Panel (CCP)
• VARITRAC III CENTRAL CONTROL PANEL (CCP)
• Tracker EMTK

Original wave: wave4876