AERMEC MCR Manuel D'utilisation page 32

SEASON CHANGEOVER ON THE BASIS OF THE WATER
If the thermostat is configured as two-pipe hydronic unit (dip7 OFF) and with probe upstream of valve (dip8 ON), the detected water temperature is that actually available on
the terminal, so the season is overrun to Hot or Cold depending on this temperature.
SEASON CHANGEOVER ON THE BASIS OF THE AIR
There are certain types of system in which the season changeover depends on the air:
— 2-pipe systems with a Water Probe downstream of the valve.
— all 2-pipe system without a water probe.
— All 4-pipe systems.
The season changeover takes place on the basis of the following criterion:
— Cooling mode: if the room temperature is lower than the set value and the difference is equal to the dead band (2°C o 5°C), heating mode is activated.
— Heating mode: if the room temperature is higher than the set value and the difference is equal to the dead band (2°C o 5°C), cooling mode is activated.
Attention: The dead zone is set through dip9: if dip9 OFF the dead zone is 5°C whereas if dip9 ON the dead zone is 2°C.
ANTI-FREEZE PROTECTION
The anti-freeze protection function makes sure the ambient temperature never falls to freezing values (even when the selector is OFF).
If the temperature falls below 7 °C, the thermostat works in HEATING with a SET value of 12 °C and AUTO ventilation, as long as the water temperature allows it.
The thermostat quits anti-freeze mode when the ambient temperature rises above 9 °C.
EXTERNAL CONTACT LOGIC
The thermostat also has an external contact that allows it to be set to OFF mode if it is closed.
This contact can be useful for managing inputs such as window contact, faulty circulation pump, etc.
Input status CE (DI1)
Closed
Open
SLEEP FUNCTION
The Sleep function in the chilled beam thermostat is available if the thermostat has been interfaced to a presence sensor (with normally open logic) connected to its DI2 input.
The function consists of varying the control setpoint of the cold beam if the room to be air-conditioned is not occupied, i.e. lowering it if it is operating in hot mode and in-
creasing it if it is operating in cold mode. This function is therefore aimed at saving energy.
In the specific case where the controller has been connected to a presence sensor, the logic of input DI2 is as follows:
Water DI2
Open
Closed
On the basis of Table 7, the new adjustment setting will be defined by the following calculation:
Setpoint = Set value - ∆ (Equation 1: for stand-alone thermostats)
Setpoint = Global setpoint - ∆ (Equation 2: For thermostats connected to a BMS or VMF-E6 panel)
The input is inhibited if the thermostat is operating in anti-freeze mode or emergency mode due to the ambient probe.

N.B.: The season changeover (air side) is inhibited as long as the DI2 input is closed, to prevent any incorrect status changes caused by the variation in the setpoint.
COMFORT FUNCTION
In centralised systems where there are chilled beams connected to the RS485 serial network, the setpoint of these is decided by the supervisor, the user may be given the
option of increasing or decreasing the setpoint according to the table below.
Dead zone [°C]
2
5
EMERGENCY OPERATION
The MCR thermostat provides for the management of emergency operating conditions dictated by the absence or breakage of the control air probe. If this condition occurs,
the controller deactivates the valves and leaves the fresh air damper open.
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Controller status
OFF
ON
Heating
Dip 9 Off Dip 9 On
Δ=0
Δ = 5°C Δ = 2°C
Deviation from set point [°C]
+/- 3
+/- 6
Dip 9 Off
Δ=0 Δ=0
Δ = -5°C
Cooling
Dip 9 On
Δ=0
Δ = -2°C
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