Compressors; Rotation; Timing; Compressor Alarms - Lennox @DNOVA pCO1 User Manual

2.7 Compressors

Compressors are managed in ON-OFF mode. Maximum 2 compressors can be present.

2.7.1 Rotation

Compressors rotation follows the F.I.F.O. (first in, first out) logic. The first compressor turned on is the first to
turn off, the first compressor turned off is the last to turn on. This logic allows comparing the compressors
working hours and obtaining the same ageing. The rotation can be disabled.

2.7.2 Timing

START MINIMUM TIME
It represents the compressors start minimum time (in seconds) after they have been enabled. If a stop
request arises, compressors are disabled only after the established time has elapsed.
STOP MINIMUM TIME
It represents the compressors stop minimum time (in seconds) after they have been disabled. If a start
request arises, compressors are enabled only after the established time has elapsed.
MINIMUM TIME BETWEEN DIFFERENT COMPRESSORS STARTS
It represents the minimum time interval (in seconds) between start of a device and the following one. This
interval allows preventing contemporary peaks, which would cause a high energy absorption.
MINIMUM TIME BETWEEN COMPRESSOR STARTS
It represents the minimum time interval (in seconds) between two starts of the same device. This parameter
allows limiting the number of starts per hour. If, for example, the maximum number of starts per hour allowed
by the default values is 10, this limit can be respected by setting a 360-second time interval.

2.7.3 Compressor alarms

Compressors alarms are distributed in two digital inputs, the alarms mean Thermal alarm / High and Low
pressure alarm.
HIGH PRESSURE – THERMAL ALARM
Immediate alarm originated by external pressure switch or compressor overload; the digital input switches
from closed to open and compressor is immediately stopped. To start the compressor again, the user has to
rearm the alarm manually by pushing the display Alarm button, provided that the pressure switch or
compressor overload have rearmed energising the digital input. After the compressor has turned off, timing is
enabled; for this reason, after alarm rearming, the compressor could not immediately turn on again.
LOW PRESSURE ALARM
Delayed alarm originated by an external pressure switch. When opening, the digital input enables two timers;
if, when the timers delay time (programmable by screen) elapses, the contact is open, the compressor turns
off and the alarm goes off. On the contrary, if the contact closes before delay time elapses, the alarm does
not go off and timers reset. Timers are: running compressor delay time and compressor start delay time.
Running delay is always counted, whereas compressor start delay is counted only if the input opens
immediately after compressor start and allows for fluid stabilisation. The two timers are counted in sequence.
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