M0G140F7-01 06/11/07
pag
24
SET-POINT CORRECTIONS
The correction aim is to optimize the unit energetic efficiency.
To do this the corrections modify the set point in a dynamic way in function of determined variables: for example in summer
operating with low outside temperatures, so with a reduced charge, is possible to obtain the internal comfort also with set point
higher than standard, obtaining an higher energetic efficiency.
CORRECTION
ACTUAL or correct set point
(visible at status 1)
static
set point
The static set point can so be modified in a dynamic way by two CORRECTIONS based on as many unit external factors:
•
correction based on the ext. temp. / enthalpy
•
correction based on the Water reset (4-20 mA signal provided by the Client)
The correct set point, to whom have been summed or removed the corrections, is named ACTUAL set-point and it is visible at
status n°1.
The STATA menu visualizes the compensation value on the ext. temperature (status 5) and WR (status 6)
For further details see the ELECTRICAL CONNECTIONS section
DEFROSTING
The defrosting aim is to maintain the external coil free from ice during the winter mode : to do that the unit is periodically
commuted in “summer” mode for few minutes and the fans are stopped.
The defrosting phase is started when the evaporating pressure falls below a fixed value . A count starts and at its end, if the
temperature on the coil is lower than the threshold, the defrosting starts .
The count changes according to the outside temperature and to the ice quantity on the coil ( by some indirect variables ) .
When defrosting is complete, the unit returns automatically to the Winter mode.
Defrosting is managed according to the outside temperature and humidity in the air:
•
more humidity = frequent defrosting
•
outside temperature next to 0°C = frequent defrosting
By the EXTERNAL HUIDITY PROBE option cod PE2N0005 the defrosting is optimised according to the outside temperature
and humidity .
CIRCULATION PUMP
The pump is always activated with the units ON.
The delivery capacity is variable to soften the thermal shock to the compressors when the plant temperature is close to the
threshold limits.
Delivery capacity depends on the intake temperature:
•
SUMMER: high water temperature reduces delivery
VENTILATION
Fans are controlled with a variable speed:
•
in SUMMER, the speed increases according to the increase of external air temperature
•
in WINTER the speed increases according to the decrease of the external tempe
SET POINT
SET-POINT CALCULATION:
•
desired medium supply water temperature = 7°C
•
Project temperature differential = 5°C (that is return water = 12°C)
•
¼ of the project temperature differential = 5 / 4 = 1.25°C
set-point to be set = 7 – 1.25 = 5.7°C
SECONDARY SET POINT – ECO
A secondary set point can be used with different levels to the “normal” set point.
It is normally set to give lower energy consumption with respect to the comfort setting:
•
The SECONDARY SUMMER set point is higher than the SUMMER setting.
It can be set according to individual requirements.
•
Secondary summer set-point parameter 29
It can be activated from the keyboard, supervisor unit or the remote control.
•
To change it using the remote control refer to the ELECTRIC WIRING paragraph.
If the 3-way valve option for sanitary water is present, the 2° set point in heating can be activated by service/remote keypad
with par 49 =1.
par Description
Meaning
value
49
Comando2°Set
2° set point mode control by parameter
0
