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ISSUE OR CONCERN
My outdoor temperature reading on
the STATUS menu is not accurate.
If my enthalpy sensor drifts in accu-
racy over time, can I re-calibrate it?
Can I go back to factory defaults and
start over?
Will I be able to see the LCD screen
when it is in the unit?
What is a good setpoint for the Sup-
ply Air Temperature (SAT)?
I am using enthalpy sensors. Why did
the control ask me to input a dry bulb
changeover temperature?
In checkout, the outdoor damper
closes when I command it to open.
How do I set the minimum position?
What if my damper does not go
completely closed in the checkout
operation?
How do I set the OCC?
Does the economizer save my pro-
gram values if the unit loses power?
If the unit is left in checkout, how
long will the unit stay in checkout
mode without input?
Table 18 — Operating Issues and Concerns
Check the sensor wiring:
• Enthalpy sensors are to be wired to the S-Bus terminals.
• Temperature sensors are to be wired to the OAT and MAT terminals.
See Fig. 77.
Sensors cannot be re-calibrated in the field. However, the ADVANCED menu includes an item where you
can input a limited offset in temperature and humidity for each sensor connected to the economizer.
Under the SYSTEM SETUP menu you can change the setpoints to the factory defaults.
The LCD screen has a backlight that is always illuminated.
The supply air temperature is the temperature of air that you want to supply to the space. In a commercial
building, this is 50°F to 55°F (10°C to 13°C). The supply air is the mixing of the return air and the outdoor
air.
If 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.
Check the actuator linkage or rotation. In the CHECKOUT mode, the outdoor damper should drive open or
closed with the return air damper having the opposite effect.
The minimum position is set using the VENTMIN and VENTMAX setup in the SETPOINTS menu. VENT-
MIN is the minimum ventilation required when using an occupancy sensor and VENTMAX is the minimum
ventilation when not using an occupancy sensor for Demand Controlled Ventilation. The VENTMAX position
is set the same as with the potentiometer on the analog economizers, and is the output voltage to the
damper actuator. The range is 2 Vdc closed OA damper and 10 Vdc open OA damper.
Check the damper linkage or hub to make sure the damper is able to close completely.
There are two settings for OCC, INPUT and ALWAYS. INPUT is from the space thermostat, if it has an
occupancy output. ALWAYS is the unit in the occupied mode, if the economizer is powered (fan on).
Yes, once the changes are stored in the controller they will be stored until they are changed by the operator.
The unit will remain in checkout for 10 minutes, then return to normal operation.
Fig. 77 — Typical Economi$er
POSSIBLE CAUSE AND REMEDY
X Wiring Diagram
®
62
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