EVCO S.p.A.
c-pro 3 OEM HRV | Application handbook ver. 4.0 | Code 144CP3OHE404
page 105 of 138
7.29
Ambient temperature probe error
If an error occurs on the control probe, the speed defined by the manual set point FSM will be used or if the time bands are active, the set point of the active time band
(FSC, FSE or FSN depending on the band).
8
Main controls
The unit regulates both the temperature and the humidity. Both adjustments include a Neutral Zone (parameter
Pb03
for temperature and
PU02
for humidity) within
which no adjustment is made. The adjustment logic is shown below.
The
temperature regulation
works on the heating and cooling coils in order to maintain the temperature as close as possible to the setpoint.
The diagram below shows a purely proportional system even if the regulation includes an integral part enabling errors to be cancelled while up and working.
Pb01:
Proportional band for temperature regulation
Pb02:
Integral time for temperature regulation
Pb03:
Neutral zone temperature regulation
Humidity regulation
acts on the humidifier and on the dehumidification process (using the cooling coil) to keep the humidity as close as possible to the setpoint. The
humidification process can be carried out using an On-Off humidifier.
The diagram below shows a purely proportional system even if the regulation includes an integral part enabling errors to be cancelled while up and working.
PU02:
Neutral zone humidity control
PU03:
Humidity regulation proportional band
PU04:
Humidity regulation integral time
For both of the controls (humidity and temperature), the
Neutral Zone
is positioned around the setpoint. The starting point of the respective regulation functions are
respectively:
SP + (ZN/2)
and
SP - (ZN/2)
.
8.1
Cooling and heating regulation
It is possible to configure which probe, either the supply or return probe, to use for adjustments, using parameter
PC10 - Control probe
. In direct expansion units, this
parameter is forced by using the return probe so any change will have no effect. If both probes are present and an error condition occurs on the selected probe, the
other probe will be used until the error condition of the adjustment probe is solved.
If there is a return/room probe as well as the supply probe and having chosen the latter as the control probe, the adjustment will be in a “cascade”. The temperature
setpoint for the supply air depends on the differential in room temperature in relation to the setpoint.
The valve is controlled by a proportional algorithm (P) or by a proportional integral controller (PI). The reference probe is the for the supply temperature as described
in the following sections.
Proport. range for
humidity regulation
Set Point
Humidity (%)
PU02: ZN
Differential
0%
100%
Humidification
Dehumidification
Set Point
Temp. (°C)
Pb03: ZN
Differential
Proportional range for
temperature regulation
0%
100%
HEATING
COOLING
