20
ENG
easy/easy compact/easy split +030220791 - rel. 3.2 - 13.07.2010
4.7 Defrost
For the correct and safe use of the easy, easy compact and easy split
controllers, it is essential to program defrost cycles.
Type of defrost (parameter d0):
The defrost may be performed by stopping the compressor, heater or
hot gas.
In addition, it can be managed:
• by temperature: using the defrost probe located on the evaporator. In
any case, the defrost will end after a maximum settable safety duration.
The end defrost for maximum duration alarm “Ed” (parameter A8) can
be disabled.
• by time: when there is no defrost probe.
• by time with temperature control (heater only); for a programmable
time: the defrost output is only activated when the temperature is
below the end defrost threshold, guaranteeing energy saving and
defrosting of the evaporator even in more extreme situations (see Fig.
4.g).
1
2
3
dP
ON
dt
dt-1 °C
t
t
t
OFF
ON
OFF
Fig. 4.g
Key
1 defrost call;
2 defrost temperature probe;
3 defrost heater.
d0 type of defrost type of end defrost
0 heater by temperature
1 hot gas
2 heater by time
3 hot gas
4 heater with temperature control
Table 4.e
Important: on the easy and easy compact models and the easy
models without defrost relay, defrost can only be performed by
stopping the compressor. In these cases, the defrost may be managed by
time (recommended d0=2) or temperature (if the defrost probe is present,
recommended d0=0).
How to start the defrost:
• from the keypad pressing the DOWN button for 3 s (manual defrost)
(for easy split H1 must be ≠4. If H1=4 the UP and DOWN buttons can
be pressed together, when H6=1);
• by digital input (in the models where tted, setting parameter A4=3);
• from the supervisor;
• setting the time bands (if RTC available /enabled);
• at the end of the interval between two defrosts (parameter dI>0);
• when switching the instrument on (parameter d4=1).
Important: the easy compact models, not having the RTC nor
the digital input, cannot be set with defrost time bands and
cannot be connected to an external contact for defrost management.
The defrost may be called, but not activated, in the following
cases:
• continuous cycle;
• dripping (dd>0);
• post-dripping ( Fd>0);
• compressor protectors;
• o status;
• disabling from digital input(A4=2);
• setting the time delay (d5>0) for the defrost function when the
instrument is switched on (d4=1);
• direct control mode only without defrost (r3=1) or reverse (r3=2) (in
this case the defrost is not called);
• defrost by temperature (d0=0, 1) and temperature measured by the
defrost probe above the end defrost set point (dt).
The defrost ends correctly:
• at the end of the pre-set time (see parameter “dP”);
• once having reached the set temperature (dt).
When the defrost ends correctly, the dripping (equal to the time set for
parameter dd) and post-dripping (parameter Fd) phases start.
The defrost ends early:
• from the keypad, pressing the DOWN button for 3 s (manual end
defrost, for easy split H1 must be ≠4 or pressing UP+DOWN together
3 s when H6=1);
• due to an immediate external alarm “IA” ;
• due to a dirty condenser alarm “CHt”;
• by setting direct mode only without defrost (r3=1) or reverse (r3=2);
• switching o ;
• when requested from the supervisor;
• from digital input (see parameter A4=2) (the defrost call remains
pending).
In these cases, the early end of the defrost is not followed by dripping
and post-dripping.
Important:
• the defrost is only available in direct mode, that is, when parameters
r3=0 or A4=9 (the latter has priority over r3);
• using parameter d0, and according to the model available, type of
defrost to be activated can be selected;
• the defrost has priority over normal temperature control; it may also
have priority over the compressor protectors (see parameter d9);
• during the defrost, the temperature display can be frozen (see
parameter d6);
• the continuous cycle has priority over the defrost
Parameters for con guring the defrost
dI: interval between defrosts
The defrost is performed periodically at a frequency of every “dI” (in hours
or minutes, see parameter dC).
The interval starts counting from the start of the current defrost. If the time
is equal to 0 (dI=0), the defrost is not performed, except when activated
from the keypad, by digital input, from the supervisor or by time band.
During defrosts the temperature alarms are inhibited.
dt: end defrost temperature set point/defrost temperature threshold
with temp. control
For the models tted with end defrost probe, this parameter allows an
evaporator temperature to be set at which the defrost is stopped (the
evaporator temperature is measured by the defrost probe). The end
defrost temperature di erential is xed at 1° C (defrost with temperature
control, d0= 4).
If at the start of a defrost cycle with the controlled output by temperature
(d0=0, 1) the temperature measured by the probe is greater than the
value set for “dt”, the defrost is not performed.
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