Operation Description - Lennox PCUS User Manual

The heating / cooling valves are activated, according to the chosen operating mode, according to the difference
between the set point and the chosen control probe, which can be the room temperature probe or the supply
temperature probe.in both cooling and heating mode and provide reliable and accurate operation in all conditions
all year round.

2.8 OPERATION DESCRIPTION

An important feature of the PCUS system is its adaptability to various possible solutions through the destination
programming of hardware inputs / outputs through the use of dip switches and parameters at the manufacturer level.
There is a user parameter menu accessible for changing the various set points.
The manufacturer parameters are set directly in the factory in the unit construction phase and must not be changed
under any circumstances since incorrect programming does not allow the unit to function properly.
In normal operation, the fans operate at low, medium, high speed and the transition from one speed to another
occurs by pressing the ventilation button (3).
The indication of the active speed is shown by the vertical bars of line 9, where two bars on indicate low speed,
three bars on indicate medium speed, five bars on indicate high speed.
The temperature is adjusted through the use of active devices (if any) such as water valves or electric resistances.
The modification of the set point is possible with the + and - keys and is automatically saved after a few seconds
of waiting without having pressed any key.
It is possible to adjust the temperature in hot mode, in cold mode or automatically in accordance with the mode
chosen with the Mode key as long as this adjustment is appropriately configured at the manufacturer level.
If at the manufacturer level only heating mode adjustment is envisaged, this mode will be fixed with the 10C icon
always active and pressing the Mode key will have no effect.
Similarly, if at the manufacturer level only adjustment in cold mode is provided, the 10C icon will be permanently
active and pressing the Mode key will have no effect.
Finally, if no temperature adjustment is selected at the manufacturer level, none of the icons 10 A, 10B, 10C will be
active and pressing the Mode key will have no effect.
In the graphic area identified by line 3 in the figure you can see the recovery section represented by the central
diamond, the flashing arrows indicate the status of the fans in operation.
This line is noteworthy because there can be different signals on unit operation: if only the recovery section without
the arrows is visible, it means that the fans are not in operation (typically this situation occurs when the unit is
equipped with shutters and at start there is the shutter opening waiting time during which the fans are off); if, on
the other hand, only the arrows are visible without the recovery section, it means that the bypass of the recovery
section has been activated (typically this situation occurs when the free coooling or free heating operation is active
if provided for in the unit).
Also in this line, the activation of the recovery defrost function (if active) is highlighted, detectable by the fact that
the recovery section starts flashing.
The icons of the exhaust air fan (identified by E A) and fresh air (identified by F A) and the temperature of the
ambient probe if the unit is equipped with this probe are visible in the graphic area indicated by line 2.
In the graphic area identified by line 4 there are four icons that indicate respectively: dirty filters signal, active
antifreeze signal, active water valve signal, active heater signal.
These signals will be visible when the unit is equipped with these devices and if one or more of them are active.
Lines 7 and 8 display the current time and day of the week respectively.
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