AP Expert VT-110, User Manual

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Chapter 9: Ventilation and Cooling
Variable speed fans
Variable outputs are activated when their associated fan stage starts. They start running at their absolute
minimum speed and their speed gradually increases as the room temperature increases. Variable outputs
reach their full speed when the start temperature of the following fan stage is reached.
Transition between fan stages 1 and 2
If the next stage is an ON/OFF fan stage, the variable output is deactivated when the new stage starts. If
the next stage is another variable fan stage, the speed of the first variable stage is reduced to its stage 2
and above minimum speed (set in the installation menu) when the second variable stage starts. This
ensures a smooth transition between both stages.
The bandwidth is the temperature interval over which variable outputs go from their minimum to their
maximum speed. This is true even if full speed is never reached as in the example below: when stage 2
starts, the controller decreases the speed of variable outputs to the initial speed associated with stage 2.
It then uses the bandwidth to increase the fan speed as the room temperature rises.
If an outdoor temperature probe is used, it is possible the controller can automatically adjust bandwidths
1-2 as a function of the outdoor temperature as shown in the following graph.
36 890-00081 Expert VT-110