The default low limited mixed air configuration is 56°F. This can be adjusted by Pelican Technical Support.
What is an economizer low limited mixed air temperature?
When an economizer cycle is active, the PEARL will modulate the outside damper to prevent the mixed air temperature from dropping below the low limited temperature configuration.
How does the PEARL calculate where to place the outside damper during an economizer cycle?
The PEARL analysis the delta temperature (ΔT) between the room and the outside to calculate what position to initially place the outdoor damper to, with a goal of not exceed the low limit temperature. It continually modulates the outdoor damper to prevent the mixed air from exceeding this low limit.
It is important the PEARL’s outdoor sensor is placed in a location where it is not being influenced but sun load or wind, so that it can accurately calculate this initial position. It is also important for the PEARL’s supply sensor to be reading an accurate supply temperature to prevent low limits from being met.
Why does the PEARL use the supply sensor veruses a mixed air sensor?
The supply sensor reads the same as a mixed air temperature and includes of any mechanical systems (ERV, HRV, DX compressors, reheats, etc.) influencing the temperature of air being supplied into the room. For most installations, even in extremely cold climates, as long as the outdoor and supply sensors are installed correctly and reading accurate temperatures, the PEARL will reliably limit the mixed air temperature.
Does Pelican alarm if the mixed air gets colder than the configured low limit when economizer and compressors are active?
This is not a default alarm notification, but can be configured.
This configuration can be found in the Pelican Web-App > Admin > Thermostat Configuration > ‘select any thermostat‘ > Input Sensor > Function: Supply Temperature > Cool Safe Range.
The Cool Safe Range tells the thermostat that if the thermostat is in a cooling cycle (compressors are enabled) and the supply temperature is not within the configured temperature range within 4 minutes after the compressors were enabled, then to send an alarm.