MAXA i-32V5C MIDI 0121 - Defrosting, Set-point Management, and Minimum Hz

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Controllo per i-32V5 MIDI Air/water inverter chillers and heat pumps with axial fans
DHW CALL FROM DIGITAL INPUT
If DHW operaon is enabled and parameter H51 = 28, is set, as an alternave to using the DHW temperature probe (H17 = 0), the DHW funcon
can be acvated by closing/opening digital input DI7. The unit goes into DHW mode when the contact closes and exits DHW producon when
the contact opens.
The polarity of digital input ID7 can be inverted by seng H75 = 64.

This funcon is recommended when using two or more heat pumps in cascade, hydronically connected to the same domesc hot water storage
tank. In this case, the acvaon of the domesc hot water funcon can be set on the rst machine via the DHW probe of the tank, while the
other machines are automacally enabled thanks to the consent given by the digital input.


SYSTEM WATER REMOTE PROBE
In some system soluons (e.g.: heat pump in parallel with the boiler on the same hydronic circuit and exclusion diverter valve) it may be neces-
sary to enable a temperature probe of the system so that the on-board control can process the management correctly. The system remote probe
is acvated by seng parameter H18 = 41.
The system remote probe thermoregulates the heat pump only during the compressor start-up phase, the switch-o is managed by the probe
on the heat pump delivery.
In heang mode, the call is acve if the following condions are veried:
• Flow probe temperature < ;
• Temperature of the system remote probe <  (default b22 = 5,0°C).
In cooling mode the call is acve if the following condions occur
• Flow probe temperature > ;
• Temperature of the system remote probe >  (default b22 = 5,0°C).
14. DEFROSTING CYCLE
The defrost cycle is a funcon acve only in heat pump mode and is used to prevent the formaon of ice on the surface of the nned coil. The
formaon of ice on the evaporator, which occurs more frequently at very low external ambient temperatures, not only considerably reduces the
thermodynamic eciency of the machine, but also leads to the risk of damage to the machine itself.

15. 
This funcon introduces a second working set-point on the plant side, both in cooling and heang mode.
The user terminal board allows a consent to be connected to switch from the rst to the second set-point and congured at digital input DI9 with
parameter H53 = 26. The valve,on the other hand, is connected in the terminal board to digital output DO7 and is congured via parameter H85.
Parameter VALUE 
H53 26 Call for second set-point
H85 25 3-way valve for radiant panels
H129
0 Funcon disabled
1 Funcon congured but not acve
2 Enabled only in cooling mode
3 Enabled only in heang mode
4 Enabled in cooling and heang mode
16. MINIMUM HZ FUNCTIONS
Conguring parameter L02=1 and L03≠0 reduces the nominal operang Hz of the compressor.