Data Sheet for Product

7/16
Building Technologies Fan coil controller for wall mounting ACR12 CE1N3578en
HVAC Products 03.10.2005
Fan Operation
When the fan is automatically controlled (manual fan speed selector switch on the con-
troller set to "Auto“) then in the neutral zone (control-free zone) of the normal operating
mode the fan remains either constantly on or is switched off after 2 to 3 minutes. The
actual behaviour is defined by P08.
In the reduced mode the fan is always switched off in the neutral zone.
When the fan starts from zero, then it starts with speed 3 for 1 second in order to guar-
antee a safe start (to overcome inertia and friction).
In automatic mode the fan is switched to speed 1 (if not already there) when the con-
troller output crosses 10 %. At 80 % speed II is switched on and at 100 % speed III.
The switching hysteresis of the fan speeds are shown in the following diagram.
Q1
Q2
Q3
010
50
80
100
0105080100
3573D06
Q
K
[%]
Q
H
[%]
W
H
W
K
X
p
X
p
X
dz
This behaviour is selected with P08 = ON or 1
If an external temperature sensor (e.g. return air sensor) is connected (only possible
with 4 pipe fan-coil mode), then the fan is periodically switched on for 2 min. every 30
min. as long as the controller is in the neutral zone.
W
H
W
K
X
p
X
p
X
dz
Q1
Q2
Q3
50 80 1005080100
3573D07
Q
K
[%]
Q
H
[%]
This behaviour is selected with P08 = OFF or 0.
In automatic mode a freeze (or hold time) of 1 minute is active. This means that the fan
remains at least for one minute at one speed until it is switched to the next.
Q1 Fan speed 1 W
H
Heating set-point
Q2 Fan speed 2 W
K
Cooling set-point
Q3 Fan speed 3 X
p
P-band
Q
H
Heating load X
dz
Neutral zone
Q
K
Cooling load
Valve Actuators
Thermal valve actuators for AC 230 V voltage must be used.
The control algorithm is optimised for STA21 and STP21 actuators.
Motor on/off valves must not be used.
Neutral zone
Start
AUTO mode
Ventilation OFF in
neutral zone
Periodical Fan
V
entilation always ON
Freeze time
Legend
Important note