Orion System VAV/Zone Controller - Manual (Page 21)

VAV/Zone Controller
Technical Guide
21
If all the above tests are passed, the zone temperature and setpoints are
then included in the HVAC Mode decision, otherwise, this zone is ig-
nored.
Testing for Maverick Zones
During the HVAC Mode decision process, a zone cannot be included in
the Voting if it has been declared as Maverick. A zone is determined to
be a Maverick if it stays 4 ºF below the Space Heating setpoint for 1
hour or 4 ºF above the Space Cooling setpoint for 1 hour. During this 1
hour time period, the zone is still included in the voting, but it generates
a PRIORITY call for heating or cooling to the MiniLink PD. During
this 1 hour time period, if the Space Temperature moves to within 2 ºF
of its Space Heating or Space Cooling Setpoint, the PRIORITY is can-
celed. If the zone stays in PRIORITY for greater than 1 hour it then
becomes a Maverick zone. At that point its PRIORITY is canceled and
the zone is ignored in the voting process, until the Space Temperature
changes to within 2 ºF of its Space Heating or Space Cooling Setpoint.
If at least 75% of the zones go Maverick simultaneously, the MiniLink
Polling Device assumes an abnormal condition has occurred in the build-
ing and resets all the zones back to normal. It then restarts the 1 hour
Maverick test over again for all zones. Maverick testing can be dis-
abled if your system is connected to a personal computer with the Prism
computer front end software installed.
Alarm Detection And Reporting
The VAV/Zone controller continuously performs self diagnostics dur-
ing normal operations to determine if any operating failures have oc-
curred. These failures can be reported to the user in several ways, de-
pending on the type of system and options installed by the user. If a
System Manager or a Modular Service Tool is connected, the alarms
will be reported on the Status Screens. If the Prism computer front end
software is installed, the alarms will be reported on the main screen of
the program and be logged to disk. If the remote communications op-
tion is installed, all alarms except the Damper Feedback Failure con-
dition can initiate a callout to a pager to alert someone to the alarm
condition. See the computer front end program operations manual for
further information on this topic.
Internal Trend Logging
The VAV/Zone controller continuously maintains an Internal Trend Log,
which records a fixed set of values at an interval programmed by the
user. These values can be retrieved only with the graphical front-end
program. In order to utilize these logs, a computer with Prism front end
software installed must be connected to the Orion system.
There are 120 log positions available. Once the last (120th) position
has been recorded, the log jumps back to the first position and begins
overwriting the old data. This means the user is required to retrieve the
logs at an interval that is shorter than the duration of the last 120 logs.
Shown below are some log intervals and the duration of 120 logs.
1 Minute Interval .......................... 2 Hour Duration
15 Minute Interval ........................ 30 Hour Duration
30 Minute Interval ........................ 60 Hour Duration
60 Minute Interval ........................ 120 Hour Duration
The fixed items in the log are listed below:
•
Date
•
Time
•
Space Temperature
•
Active Cooling Setpoint
•
Active Heating Setpoint
•
Supply Air Temperature
•
Airflow on Pressure Independent Terminal Units
•
Damper Position
Note: For proper time and date stamping of the tenant log,
you must configure VAV/CAV Controller to broadcast
the time so that the VAV/Zone controllers can read it and
use it in their tenant and trend logs.
Caution:
These logs are subject to loss if a power outage
occurs because there is no battery backed memory
on the VAV/Zone controllers.
Force Modes or Overrides
The VAV/Zone controller damper can be forced to one of several posi-
tions. These force modes aid the user during troubleshooting or air bal-
ancing, etc.
•
Force Damper Full Open (Ignores Airflow Reading )
•
Force Damper Full Closed (Ignores Airflow Reading )
•
Force to Maximum Airflow/Damper Setpoint
•
Force to Minimum Airflow/Damper Setpoint
•
Force to Fixed Airflow/Damper Setpoint
•
Force Damper to Re-Calibrate
The Force to Fixed Airflow/Damper mode also has a setpoint associ-
ated with it. This allows the user to provide a non-changing fixed amount
of air into the space that doesn’t affect the Minimum or Maximum
setpoints. That means the user doesn’t have to disturb the real minimum
and maximum setpoints to achieve a nonstandard setting during their
troubleshooting or air balancing modes.
The Force to Minimum mode uses the currently active minimum set-
ting based on the Vent, Cooling or Heating modes. Whatever mode the
VAV/Zone controller is in, sets the minimum used by the force mode.
The damper force modes will remain in effect until cancelled by the
user, or until the power is removed. Unlike the VAV/CAV Controllers,
which require the initiating device to be present at all times during a
force mode, the damper force modes are more permanent since they are
less likely to damage any equipment. There are no force commands
available for the auxiliary relays.