Close Control Units With Single Water Coil; Humidity Control - Lennox @DNOVA pCO1 User Manual

2.1.4 Close control units with single water coil

In these close control units, the coil provides for both heating and cooling, depending on the type of water
circulating inside it. In practice, the unit works as it was equipped with two different coils. The coil operation
depends from a Summer / Winter digital contact that "reports" whether the circulating water is warm or cold
to the board; if the "type of water" circulating inside the coil complies with the ambient request, the valve is
modulated to regulate temperature.
In addition, heating can also be executed by heaters or a warm coil. For any information about coil and
heaters operation, refer to the previous paragraphs.

2.2 Humidity control

The humidification and dehumidification devices are managed based on the humidity value measured by the
ambient (or room temperature) probe. The measured humidity is compared to the set humidity (set point);
the devices are enabled based on the difference between the two values. The proportional band identifies
the air-conditioning unit working range and can take different values in humidification and dehumidification
mode. The 0.2% fixed dead zone identifies the devices non-action zone round the set point.
Dehumidification enables the available cooling devices and a contact for an external dehumidifier or for
reducing the outlet fan speed.
Dehumidification can be executed as follows:

On-Off contact for an external dehumidifier or for reducing the outlet fan speed

compressors enabling (active capacity controls included, if any)

100% enabling of the 0-10Volt or three-position modulating cooling valve
The dehumidification On-Off free contact is always managed, whereas the cooling devices depend on unit
configuration and User selection. The 0-10Volt modulating output of the dehumidification outlet fan is
automatically reduced by 50% (modifiable); with On-Off fan, use the digital contact for reducing speed.
The following diagrams show the humidification and dehumidification devices action. The percentage values
indicate the modulating valves opening range.
6 INNOV@-pCO1-IOM-0907-E