24
Since 1965
MicroMetl
TROUBLESHOOTING
For a list of common operating issues and concerns see Table 15.
Power Loss (Outage or Brownout) — All setpoints and advanced
settings are restored after any power loss or interruption, as all
settings are stored in the economizer controller’s non-volatile ash
memory.
NOTE: If power goes below 18 Vac, the W7220 module assumes a
power loss and the 5-minute power up delay will become functional
when power returns above 18 vac.
Alarms — The economizer module provides alarm messages that
display on the 2-line LCD.
NOTE: Upon power up, the module waits several seconds before
checking for alarms. This allows time for all the congured devices
(e.g. sensors, actuator) to become operational.
If one or more alarms are present and there has been no keypad
activity for at least 5 minutes, the Alarms menu displays and cycles
through the active alarms.
The Alarms menus can be navigated at any time. See Table 11 for
the Alarms menu.
Clearing Alarms — Once the alarm has been identied and the
cause has been removed (e.g. replaced faulty sensor). They can
be cleared from the display.
To clear an alarm, perform the following:
1. Navigate to the desired alarm.
2. Press the button.
3. ERASE? displays.
4. Press the button.
5. ALARM ERASED displays.
6. Press the ↑ (Menu Up/Exit) button to complete the action and
return to the previous menu.
NOTE: If the alarm still exists after you clear it, it is redisplayed
within 5 seconds.
Table 15 - Operating Issues and Concerns
Issue or Concern Possible Cause and Remedy
My outdoor temperature reading on the
STATUS menu is not accurate
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.
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 eld. However there is a menu item under
the ADVANCED menu where you are able to input a limited o 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 the LCD screen when it is in
the unit?
The LCD screen has a backlight that is always illuminated.
What is a good setpoint for the Mixed Air Tempera-
ture (MAT)?
The mixed are temperature is the temperature of air that you want to supply to the space.
In a commercial building, this is between 50 to 55
o
F (10 to 13
o
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 tempera-
ture?
In the event 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
command it to open.
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 eect.
How do I set my minimum position when using a
CO2 sensor?
The minimum position is set using the VENTMIN and VENTMAX setup in the SETPOINTS
menu. VENTMIN is the minimum ventilation required when using an occupancy sensor
and VENTMAX is the minimum ventilation when not using an occupancy sensor for
Demand Control 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.
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.
Does the economizer save my program values if
the unit loses power?
Yes, once the changes are stored in the controller they will be stored until they are
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 10 minutes, then return to normal operation.
Manufacturer reserves the right to discontinue, or change at any time, specications, designs and prices without notice and without incurring obligations.
Copyright MicroMetl Corporation 2018 All rights reserved.
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3035 N. Shadeland Ave.,
Suite 300 Indianapolis, IN 46226
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201 Kodak Blvd.
Longview, Texas 75602
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905 Southern Way
Sparks, Nevada 89431
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