There are a few reasons why a thermostat is turning the fan ON.
Fan is set to ON.
Anytime the thermostat’s Fan button is set to ON (or if you have a two speed fan: Low or High), the thermostat will enable the supply fan.
For unitary equipment: the thermostat will enable its (G) output. This output is most commonly used to start the HVAC equipment’s supply fan.
For unity equipment with two speed fan: The thermostat will enable (G) for low speed fan and (Y2) for high speed fan.
For zoned equipment: the thermostat will request a fan/ventilation cycle from the Pelican central HVAC equipment controller. From the web-app the thermostat will indicate “waiting” until the central HVAC equipment controller confirms a ventilation/fan cycle can start. The thermostat will enable (Y) to open its damper.
How does fan switch between AUTO to ON?
- Manually at the thermostat or through the web-app.
- By the thermostat’s schedule.
What is the difference between Fan AUTO, ON, LOW, and HIGH?
AUTO: The fan will only run during a heating, cooling, and/or demand ventilation (high CO2) cycle.
ON: The fan will run as explained above.
LOW: The fan will run in low speed.
HIGH: The fan will run in high speed.
Fan is set to AUTO, but there is an active heating or cooling cycle.
Anytime the thermostat is running a heating or cooling cycle, it will enable the fan.
Note: Some HVAC have their own internal timers and/or temperature sensors to decide when to turn the supply fan on during a heating cycle. Units with their own sensors automatically enable the supply fan once the heat exchanger has reached a factory set temperature. The Pelican thermostat can be configured to not enable the fan when a heating cycle is active. Click here for more information.
Note: If you have a two speed fan (High and Low) the fan speed will automatically adjust as explained here.
Fan is set to AUTO, but there is an active Demand Ventilation cycle (High CO2 levels)
Anytime a Pelican thermostat with a CO2 sensor detects the room’s CO2 ppm above the CO2 Ventilation configuration, it will start a Demand Ventilation cycle. A demand ventilation cycle requires the supply fan to be running.
How do I turn OFF the fan even though the CO2 readings are high in my room?
Demand ventilation is considered a critical function and cannot be disabled through conventional means to prevent unintentionally leaving it disabled. If the demand ventilation must be temporarily turned OFF, you will need to set the thermostat’s CO2 Ventilation configuration above the room’s CO2 readings. Click here for more information.
Minimum Fan Circulation Minutes is being enforced.
Fan Circulation Minutes automates the thermostat to run the fan for a minimum number of minutes each hour of the day. For more information on this configuration click here.
When is minimum Fan Circulation Minutes active?
This configuration can be scheduled to always be active or only be active during specific periods of the day. Thermostats which have minimum Fan Circulation Minute configurations can be set to follow their own Customer schedule and in those schedules you can set Fan Circulation Minutes to be ON or OFF at different times.
Automated balancing is ocuring between a master and its remote thermostat(s).
If you have a master Pelican thermostat averaging its internal temperature with remote sensors, then if the temperature differences between the remotes and the master thermostat’s are far apart, the master thermostat will automatically enable the supply fan to balance out the space.