28
Table 11 – Operating Issues and Concerns
Issue or Concern Possible Cause and Remedy
My outdoor temperature reading on the STATUS men u
is not accurate
Check the sensor wiring:
S Enthalpy sensors are to be wired to the S- Bus terminals.
S TemperaturesensorsaretobewiredtotheOATandMATterminals.
If my enthalpy sensor drifts in accuracy over time, can I
re- calibrate it?
The sensor is not able to be re- calibrated in the field. However there is a menu item under the A D-
VANCED menu where you are able to input a limited off set in temperature and humidity for each
sensor you have connected to the economizer.
Can I go back to factory defaults and start over? Under the SYSTEM SETUP menu you can change the setpoints to the factory defaults.
Will I be able to see LCD screen when it is in the unit? The LCD screen has a backlight that is always illuminated.
What is a good setpoint for Mixed Air Temperature
(MAT)?
The mixed are temperature is the temperature of air that you want to supply to the space. In a com-
mercial building, this is between 50 to 55° F (10 to 13° C). The mixed are is the mixing of the return air
and the outdoor air.
I am using enthalpy sensors. Why did the control ask
me to input a dry bulb changeover temperature?
In the even the humidity sensor in the enthalpy sensors fails, the backup algorithm in the control is to
default to the temperature sensor in the enthalpy sensor.
In checkout, the outdoor damper closes when I com-
mand it to open.
Check the actuator lin kage or rotation. In the CHECKOUT mode, the outdoor damper shoul d drive
open or closed with the return air damper having the opposite effect.
How do I set my minimum position? Minimum position is set using VENTMIN and VENTMAX setup in SETPOINTS menu. VENTMIN is
minimum ventilation required when using an occupancy sensor and VENTMAX is minimum
ventilation when not using an occupancy sensor for Demand Control Ventilation. VENTMAX position
is set the dame as with the poten tiometer on the analog economizers and is the output voltage to the
damper actuator. The range is 2 VDC closed OA damper and 10 VD C open OA damper.
What if my damper does not go completely closed in
the checkout operation?
Check the damper linkage or hub to make sure the damper is able to close completely.
How do I set the OCC? There are two setting for OCC setting, INPUT and A LWAYS, I NPUT is from space thermostat, if it has
an occupancy output. ALWAYS is unit in the occupied mode, if the economizer is powered (fan on).
Doestheeconomizersavemyprogramvaluesifthe
unit loses power?
Yes, once the changes are stored in controller they will be stored until changed by the operator.
If the unit is left in checkout, how long will the unit stay
in checkout mode without input?
The unit will remain in checkout for ten minutes, then return to normal operation.
0
500
1000
1500
2000
2500
0 0.05 0.1 0.15 0.2 0.25 0.3
RELIEF FLOW (CFM)
Small
RETURN DUCT STATIC PRESSURE (in. wg)
Cabinet
Fig. 33 - Barometric Relief Flow Capacity
40QQ
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