AERMEC WMT20 User Manual Download Page 16

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set at 0.0 Economy function is actually disabled. Economy saving mode is
started from the menu button, as explained in the ‘Operation’ section. In
case the remote heating/cooling mode is not conﬁgured, terminal 7 can be
used to start the ‘Economy’ function from remote even at the same time
on several different regulators.
When the wire connected at this terminal is linked with the Live voltage
of power supply, the function is started; the same function is terminated
when this terminal is left unconnected (open). The regulator detects the
state changes of the terminal, not the level itself, therefore it is always
possible to override the Economy state set by terminal 7 with a manual
action on the menu button.
When Economy mode is active, being an energy saving mode, the fan motor
speed will be limited to the lowest one (ﬁrst) or at the value set in

P30

case of fan proportionally driven.

Dirty ﬁlter warning function

Fan-coils and other devices including a fan are often equipped with a
ﬁlter for the air in the suction path, which needs a periodical maintenance
and cleaning or replacement. This regulator can warn the user when the
maintenance has to be made, provided the ‘Dirty ﬁlter warning’ function
has been enabled.
The function is enabled by setting the time-to-maintenance value (each unit
means 100 hours) in parameter

P35

: the regulator will count the operating

time of the fan and when the value stored in

P35

(x 100 hours) is reached

it will warn the user through a message on the display.
In this situation the regulator shows on the display, in place of the room
temperature, the two words

FIL-TER

alternating. If any key is depressed

the warning disappears and the display returns to its normal mode.
Whenever the regulator is turned off and then on again, the warning will
reappear. This is an extremely useful function for the maintenance service,
which can easily check whether the ﬁlter needs to be cleaned.
In order to reset the warning and the relevant time-counter, once the
cleaning has been made, just keep depressed the speed button for at least

10 seconds, until the regulator will conﬁrm to have reset the warning by
showing again the words

FIL-TER

Temperature regulation

This device can drive in a proportional way the fan speed in order to
control room temperature with the highest comfort and energy saving.
Nonetheless each different environment needs a different set for some
parameters in order to get an accurate regulation.
Parameters devoted to the regulation accuracy are:
- Proportional band:

P26

and

P27

- Integrative time:

P28

and

P29

For each of the settings two parameters are available, because the user is
allowed to set different values for heating and cooling mode. Proportional
band, measured in °C, is intended as the difference between set-point and
room temperature which is needed to change the fan speed from zero to
maximum.
The narrower the proportional band, the fastest is the regulator to
counteract temperature variations in the room.
Yet a value for this parameter too ‘narrow’ can result in room temperature
oscillations or system instability. A value too ‘wide’ could result in the
impossibility to reach the set-point temperature in the room. When the
integrative time is set to zero, no integral action is made and therefore
the regulation is purely proportional (P type). When an integrative time
different from zero is set the resulting regulation is made of a Proportional
plus an Integral action (P + I type).
The smaller the integrative time, the greater the inﬂuence of the integral
action and vice-versa: with a greater integrative time the resulting integral
action is softer.
A too soft or null integral action could result in the impossibility to reach
the set-point temperature, meanwhile a too strong integral action could
possibly generate oscillations in the room temperature. It is necessary
to adjust these parameters according to the actual environment in which
the regulator is installed for the purpose of the best possible regulation