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English 05/09
ACCURATE AX - AW - AD - AT - AF
CALIBRATING THE AIR FLOW SENSOR
A
I
U
The differential pressure switch F3 must be activated if the fan is
not working (when there is one fan) or one of the fans is not
working. The factory calibration of the differential pressure switch
to control the air flow (F3) is 0.5 mbar (=50Pa).
As the difference in pressure between the fan intake and outlet
depends on the air flow-rate, the instrument may need to be
recalibrated after installation, checking that the contact closes
when the fan is operating normally.
To calibrate the pressure switch:
• simulate a fault in the fan system (stop the fan - if there is just
one - or one of the fans on the unit) and check that the pres-
sure switch is activated;
• if the device is not activated, progressively increase the calibra-
tion value of the pressure switch.
To calibrate the pressure switch, remove the plastic cover (A) by
unscrewing the two screws (B).
Use the adjustment screw (E) to calibrate the differential pressure
switch on a scale from 0.5 to 4.0 mbar (50 to 400Pa).
If having to replace the pressure switch, unscrew the two fasten-
ing screws (D), remove the rubber hoses connected to the pres-
sure test points (+) and (-) and remove the electrical cables con-
nected to terminals 1, 2 and 3.
To install the new pressure switch, perform the same operations
in the reverse order, inserting the cables from point (C).
+
-
A
m
bar
B
B
1
3
2
m
bar
D
C
D
E
CALIBRATING THE DIRTY FILTER SENSOR
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U
The factory calibration of pressure switch F4 is 3 mbar (=300Pa).
Pressure switch F4 must be calibrated according to the pressure
drop, which depends not only on the filter being dirty, but also on
the air flow-rate.
The calibration must be performed with a clean filter, as follows:
- switch the unit on
- progressively cover the surface of the air filter and make sure
that the pressure switch is activated when around 50-60% cove-
red;
- if the device is not activated, progressively reduce the calibra-
tion of the pressure switch;
- if the device is activated too early, increase the calibration.
Pressure test points
CALIBRATING THE PRESSURE CONTROL VALVE
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I
U
(option available for water-cooled models)
The pressure control valve, by managing the flow of water, pre-
vents the condensing pressure from lowering excessively and, at
the same time, saves water consumption.
If necessary, calibrate the pressure control valve using the adjust-
ment knob (the pressure is increased when turning clockwise)
until the condensing pressure stabilises at the recommended val-
ue of 18 bar (equivalent to a satured temperature of around 45°C
when using di R407C) and 27 bar (equivalent to a satured tem-
perature of around 45°C when using di R410A), measured using a
pressure gauge connected to the pressure test point on the out-
let valve.
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2
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