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To replace the battery
If the VVT Bypass II experiences a power outage and the control program stops functioning, replace the
battery.
You need to replace the battery if the voltage measures below 2.9 volts when the controller is not powered.
1
Verify that the VVT Bypass II's power is on.
CAUTION If the controller's power is not on when replacing the battery, your date, time, and trend
data will be lost.
2
Remove the VVT Bypass II's cover.
3
Remove the battery from the controller, making note of the battery's polarity.
4
Insert the new battery, matching the battery's polarity with the polarity indicated on the controller's cover.
5
Replace the VVT Bypass II's cover.
6
Download the VVT Bypass II.
To clean the airflow sensor orifice
In less than .02% of installations, small particulates (micron/submicron-level) can build up in the airflow
sensor's internal orifice causing airflow restriction. Symptoms of airflow restriction are:
•
Diffuser noise increases over time
•
Space overcools at minimum airflow
•
Frequency of dampers opening to maintain flow setpoint increases over time
•
AHU fan speed increases over time
To check for these symptoms, set up trending of:
•
Damper position to look for long term increase
•
AHU fan speed for maintaining static pressure
If you see these symptoms, you should clean the flow sensor.
To clean the flow sensor
You can use a can of compressed air to clean the sensors while the controller is installed or on a repair
bench.
1
Disconnect the High and Low flow sensor tubes.
VVT Bypass II Controller
Installation and Start-up Guide
37
Troubleshooting
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