Hi-T2
Centralised controller
30
The parameters to be set for the management of dehumidification are accessible from the service menu (
Configuration
->
Service
menu
->
Parameters
->
Keyboard
):
Parameter Name
Unit
Default Min. Max.
Par 42/65 Dew-point temp. margin
°C
5.0
0.0 50.0
Par 43/65 Min. time in dehumidification Seconds
300
0
600
Par 44/65 Max. time in dehumidification Seconds
600
0
1200
Table 5. Service keyboard parameters for dehumidification.
Note 1: set the lower limit of the first winter setpoint at 25°C
•
set the parameter
H129
= 3 or 4.
•
Set the secondary winter setpoint from 35°C to 25°C
•
Reset the parameter
H129
at 0
•
You may now lower the winter setpoint to 25°C.
Note 2
: if the presence of a digital input for management of the second set point is configured on the chiller (chiller parameter
H44=26
, output to second setpoint terminals, see Chiller manual), the humidity control is not managed from the remote control.
The digital input is also possibly used for switching between the first and second set point during operation in winter mode.
With double set-point function enabled, if the chiller controls the temperature on the second set-point (radiant panels side), the
double set-point icon displayed in the toolbar of the functions in the chillers and fan coils pages remains transparent.
Whereas if the chiller controls the temperature on the first setpoint (fan coil side), the double setpoint icon will be coloured.
Likewise entering into dehumidification is indicated in the chiller and fan coil toolbar by the icon switching from transparent to
coloured.
Parameter
H129>1
, means:
FLOOR SIDE FUNCTION
(2nd SET-POINT)
FAN COIL SIDE OPERATION
(1st SET-POINT)
DOUBLE SET-POINT ICON
DEHUMIDIFICATION ICON
if dehumidification is active
Table 6. Double set-point/dehumidification icons.
4.9.1
DEW POINT CONTROL
The dew point temperature will be calculated by reading the internal temperature and humidity probes.
Given the room temperature and room humidity, the controller calculates the dew point temperature (Td).
The formula used to calculate the dewpoint temperature is the Magnus – Tetens approximation. This approximation applies for
dewpoint temperatures between 0°C and 50°C. Therefore, if the calculation gives a value outside of these limits, the limit value is
assumed as the dewpoint temperature (respectively 0°C and 50°C).
Meaning of parameters:
•
Tint: room temperature detected by the indoor temperature probe (°C)
•
Tr: calculated temperature of the dew point (°C)
•
odr: adjustment offset (°C)
•
Hy: adjustment hysteresis (°C)
•
tAr: adjustment time (min.)
•
Relay activation time: 0-100% of tAr
The room temperature measured by the probe inside the controller will be compared with the dew point (evaluated at the last
moment of tAr) added to the parameters odr and Hy:
•
if Tr < Tint < Tr + odr → Double setpoint active valve output
•
if Tr + odr < Tint < Tr + odr + Hy → Double setpoint active valve output for the value in % of tAr identified on the ramp
•
if Tint > Tr + odr + Hy Double setpoint deactivated valve output for all the subsequent tAr time
The parameters tAr, odr and Hy are set in the factory and cannot be changed.
Given the environmental temperature and humidity, the Hi-T2 remote control calculates the dew point.
With plant operating in summer mode, with a double setpoint function active on chillers and temperature control normally
performed with radiant panels (second work setting), a controller is activated to maintain the dewpoint temperature at least at an
amount defined by the keyboard service parameter
Par42
:
"Dew-point temp. margin "
°C below the ambient temperature detected
by the controller itself.
