Carel FLSTDMAHUE, User Manual

Page: 41 / 94

ENG
“FLSTDMAHUE” +030220961 - rel. 1.1 - 28.08.2019 41
Temperature control
The control differentials used are those that apply to normal temperature
control.
Screen index Display description Def Min Max UOM
Gfc05 Cooling regulation
Differential
2 0 99.9 °C
Gfc06 Heating regulation
Differential
2 0 99.9 °C
When the function has been activated, the fresh air damper and mixing
damper are controlled proportionally to the cooling/heating request with
the percentages defined on Gfc20/ Gfc21. The fresh air damper opens and
the mixing damper closes to compensate for the pressure drop. If the fresh air
damper and exhaust damper are used, the two control signals are identical.
0% Min_Mix_Damper
100%
Min_Ext_Damper
Max_Mix_Damper
Max_Ext_Damper
Req_Cooling/
Req_Heating
100%
Freecooling/ Freeheating
Free_C/H
Min_Request
Free_C/H
Max_Request
Fig. 9.h
Key
Max_Mix_Damper Mixing damper maximum opening
Max_Ext_Damper Fresh air damper maximum opening
Min_Mix_Damper Mixing damper minimum opening
Min_Ext_Damper Fresh air damper minimum opening
Req_cooling/heating Cooling/heating request
The limits for opening the damper are set in the manufacturer parameters
menu, Hc02.
Screen index Display description Def Min Max UOM
Hc02 Dampers limits setting
Fresh air damper - min
- 0 100 %
Fresh air damper - max - 30 100 %
Mixing damper - min - 0 100 %
Mixing damper - max - 0 100 %
To exploit freecooling/freeheating to the maximum, a delay can be set when
starting the unit for activation of the other devices in cascade control.
Screen index Display description Def Min Max UOM
Hc03 Damper setting
Coil start delay
0 0 120 min
Note :
•
if air quality control is also enabled (see. Ha02), when both functions are
active the fresh air damper will open according to the higher request;
•
in the winter season, freecooling is especially useful for cooling. A
typical example a crowded shopping centre or conference centre. To do
this, enable “auto” mode on Gfc04 and set the freecooling parameters
accordingly.
Activation by enthalpy
Note : the following graphs consider the outside enthalpy to be constant.
Freecooling and freeheating by enthalpy are activated when:
1.
the outside enthalpy is closer to the enthalpy set point than the return
enthalpy, or alternatively
2. the outside and return enthalpy straddle the set point.
FREECOOLING ENTHALP Y
Set
ABILITAZIONE/
ENABLE
Ret_enth
Ext_enth
E
ON
diff_enth
OFF
Set
ABILITAZIONE/
ENABLE
Ret_enth
Ext_enth
E
ON
diff_enth
OFF
Fig. 9.i
ON: Ret_Enth- Ext_enth>diff_enth; OFF: Ret_Enth-Ext_Enth<0
FREEHEATING ENTHALP Y
Set
ABILITAZIONE/
ENABLE
Ret_enth Ext_enth
E
ON
diff_enth
OFF
Set
ABILITAZIONE/
ENABLE
Ret_enth
Ext_enth
E
ON
diff_enth
OFF
Fig. 9.j
ON: Ext_Enth-Ret_enth> diff_enth; OFF: Ext_enth-Ret_Enth<0
Key
Ret_enth Return enthalpy Set Enthalpy set point
Ext_enth Outside enthalpy E Enthalpy
Screen index Display description Def Min Max UOM
Gfc15 Freecooling/ Freeheating
damper setting
Enthalpy activation differential
4 0 53.5 kJ/kg
Enthalpy control
The enthalpy control set point and supply, return and outside enthalpy values
can be seen on screen D06. The control differential is set on screen Gfc15.
Screen
index Display description Def Min Max UOM
D06 Enthalpy
Supply
- 0 99.9 kJ/kg
Return - 0 99.9 kJ/kg
External - 0 99.9 kJ/kg
Setpoint - 0 99.9 kJ/kg
Gfc15 Freecooling/ Freeheating dampers
settings
Enthalpy differential
5 0 99.9 kJ/kg
When the function has been activated, the fresh air damper and mixing
damper are controlled proportionally to the freecooling/freeheating
enthalpy request. The fresh air damper opens and the mixing damper closes
to compensate for the pressure drop. If the fresh air damper and exhaust
damper are used, the two control signals are identical.
0% Min_Mix_Damper
100%
Min_Ext_Damper
Max_Mix_Damper
Max_Ext_Damper
Req_enth
Freecooling/ Freeheating
Free_C/H
Min_Request
Free_C/H
Max_Request
Fig. 9.k
Key
Max_Mix_Damper Mixing damper maximum opening
Max_Ext_Damper Fresh air damper maximum opening
Min_Mix_Damper Mixing damper minimum opening
Min_Ext_Damper Fresh air damper minimum opening
Req_enth Enthalpy request
In the case of freecooling by enthalpy, the control request will depend on
the deviation from the control set point. Control for freeheating by enthalpy
is similar.