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Fan Control
Your fan will be on when any of these conditions are present (it
can take up to 20 seconds for the fan to turn on).
FAN ON:
This setting means that your fan runs 100 percent
of the time during this period.
FAN AUTO: The AUTO setting means the fan runs only with
your heating or cooling system.
FAN CIRC:
In this setting, the fan runs at least 30 percent of
the time, including the time the fan is on while the
heating or cooling system is running. When the
heating or cooling system is not running at all, the
fan runs for ten minutes on and 20 minutes off.
Protection against fan short cycling is built into
the device.
The installer setup has the ability to extend fan operation
following a cooling cycle. When selected, the fan run time at the
end of a cooling cycle is extended 80 seconds.
Humidity Control with Fan
Select models of the W8900 can be configured to control
humidity levels while the fan is energized. This type of humidity
control does not require the heat ouput to be energized. For the
humidity terminals (HUM) to energize, the following conditions
must be met:
1. System must be in the heat mode.
2. The call for humidity (Sensed relative humidity, RH, is
below RH setpoint).
3. Fan terminal (G) must be energized through program-
ming or by pressing the fan button on the PC8900.
Cool Mode Humidity Control
(Select Models Only)
Cool dehumidification is activated when there is a call for
cooling or the sensed RH is above the setpoint. This can cause
overcooling; see Cool Mode with Reheat Feature.
