There are five common reasons why an outside damper remained closed:
The thermostat's fan is set to AUTO and there is no heating or cooling cycle active.
If there is not heating or cooling cycle active and the thermostat’s fan is set to AUTO, then the thermostat is essentially in “waiting” mode. This means that the PEARL will not open the outdoor damper until the next cycle is initiated.
To make sure a room is being ventilated during all occupied hours, schedule the thermostat’s fan to ON. This keeps the fan running and the outdoor damper will remain open for ventilation.
Outside Ventilation is scheduled to OFF or has been set to OFF.
Thermostat have a sequence option called “Outside Ventilation”. If this setting is set to OFF, either through the web-app or by the thermostat’s schedule, it tells the PEARL to not open the outdoor damper during heating, cooling, and/or fan cycles. This is a common setting during after hour (unoccupied) operations, because the facility needs to stay within certain temperature limits, but the rooms are unoccupied and do not require ventilation.
To adjust this, open your web-app > select the group the thermostat is in > select the thermostat > and set Outside Ventilation to ON to enable normal ventilation sequencing or OFF to disable all ventilation.
To adjust this in a schedule > navigate to the thermostat’s schedule and set Outside Ventilation to the correct setting during the correct times.
Note: Only thermostats that have Pelican PEARL controllers provide this setting.
An economizer and compressor cycle is active and the low limit mixed air temperature has been met.
If the outdoor temperature allows for an economizer cycle to be active, but the economizer was unable to cool the room on its own, so the PEARL enabled the compressor(s) as well: then the outside damper might be set to fully closed during the cooling cycle. This is due to the mixed air temperature going below the low limit mixed air setting, so the PEARL is preventing the outdoor damper from opening to prevent freezing the coils or damaging the HVAC unit. The PEARL will still indicate that it is in an economizer and compressor cycle even though the outside damper is closed.
Prevent Outside Ventilation - Shelter In Place is active.
In emergency situations, the Pelican web-app allows administrators to shut all outdoor dampers through a sequence call Prevent Outside Ventilation. When this is active, the thermostats will still allow heating, cooling, and fan cycles, but the outside damper will remain shut.
This setting can be found in the Pelican Web-App > Admin > Shelter In Place > Prevent Outside Ventilation
There is an alarm or issue detected by the PEARL controller.
If the PEARL has detected any issues with the outside damper actuator, its supply or outside temperature sensors, or its communication to its Pelican thermostat; then it will not open the outdoor damper.
To trouble shoot the issues, you will want to contact your HVAC contractor. Pelican Technical Support can assist with troubleshooting.
Note: If the PEARL is detecting an issue or generating an alarm, it is a good controller (it is just detecting the issue, not the reason for the issue). The reason for the alarm is a mechanical issue, not a controller issue and the problem needs to be physically addressed.
