Vallox DIGIT2 SE VKL Manual Download

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VALLOX DIGIT2 SE/VKL/MLV

DESCRIPTION OF OPERATION/ELECTRIC RADIATOR

Control of operation

Power supply to the unit can be controlled with a contactor in the
distribution panel if needed, e.g. with a timer programme. After
starting, the unit first operates at minimum power. After that power is
adjusted based either on the measurement data from air quality sensors
and/or on manual control at the control panel.

Fan speed adjustment

Manual control

Fan speed of the ventilation unit is controlled in 8 steps at control panel

Week-clock control

Fan speed of the ventilation unit is controlled in 8 steps using the week
clock in control panel

. The week clock can be used to programme

the desired fan power option and the setpoint for supply air temperature
for each day of the week and each hour in the day.

Carbon dioxide and humidity control

The fan capacity of the ventilation unit is controlled in multiple steps
depending on loads, and based on the measurement results of the air
quality sensors (CO

and %RH sensors) located in the ventilation zone.

The aim is to keep carbon dioxide and/or humidity content below the
threshold set at control panel

. It is also possible to select an automatic

search for the humidity content setpoint at control panel

. One or

more modes of control may be used simultaneously – the mode
demanding boosting is the dominant one. Fan speed varies depending
on load between the base and maximum fan speeds. The base and
maximum fan speeds can be set at the desired level at control panel

Control through voltage or current signal

The fan power of the ventilation unit is controlled in 8 steps with a
voltage signal of 0...10 VDC, or with a current signal of 0...20 mA.
However, fan power cannot be raised above the set maximum fan
speed. Voltage or current signal control is used to control base fan
speed. This means that fan speed can be raised when necessary, but
not lowered, by the manual, CO

and %RH controls.

Supply air temperature

Supply air temperature can be controlled with either constant temperature
control or cascade control.

Supply air constant temperature control

The control unit directs the operation of post-heating unit

LP2

on the

basis of the measurement data given by temperature sensor

TE2

, aiming

at keeping supply air temperature at the temperature value set on
control panel

(+10…+30 ºC).

Supply air cascade control

The control unit directs the operation of post-heating unit

LP2

on the

basis of the measurement data given by extract air sensor

TE4

, aiming

at keeping extract air temperature at the temperature value set on
control panel

(+10…+30 ºC).

Heat recovery bypass

Heat recovery is enabled whenever post-heating has been switched
on. Automatic heat recovery bypass is active whenever post-heating
has been switched off and outdoor temperature exceeds the setpoint
(to be set between 0 and +25

C). In this case, the control unit directs

the operation of damper motor

on the basis of measurement results

given by outdoor temperature sensor

TE3

and extract air temperature

sensor

TE4

. The aim is to get as cool supply air to the ventilation zone

as possible. Heat recovery is, however, on whenever outdoor temperature
is below the limit set, or whenever outdoor air is warmer than extract
air.

Heat recovery antifreeze

The control centre of the unit controls the operation of preheating unit

LP1

on the basis of the measurement data of temperature sensors

TE1

and

TE3,

preventing freezing alerts and the stopping of supply air fan

. If the capacity of preheating unit

LP1

is not sufficient or it is not on,

the control centre keeps stopping supply air fan

on the basis of the

measurement data on temperature sensor

TE1

and

TE3

, thus preventing

the heat recovery cell from freezing. As soon as the risk passes, the
fan restarts automatically. The threshold temperature (-6...+15

C) and

the difference area (1 ...10

C) for antifreeze can be set at control

panel

. When fan

stops, power supply from radiator

LP1

is stopped

and post-heating radiator

LP2

continues to heat.

For preheating to work, its threshold temperature has to be set at least
one degree higher than the threshold temperature controlling fan
stopping. Temperatures are adjusted at control panel

Overheat protection for the heating element

Overheat protection thermostats

TS1

and

TS2

monitor the surface

temperature of heating unit

LP2

and overheat protection thermostats

TS3

and

TS4

that of

LP1

. If surface temperature exceeds the threshold,

overheat protection is triggered and power supply to the heating unit
is stopped. Overheat protection for

TS1

and

TS3

is reset automatically,

whereas overheat protection for

TS2

and

TS4

is reset manually.

Alarms

Pressure difference switches

PDE1

and

PDE2

monitor the pressure

difference on the supply and extract air sides. If the pressure difference
rises too high because of dirty filters or clogged ducts, an alarm will
be issued. This is indicated by a symbol ( ) in the main display of the
control panel. If the unit is not equipped with pressure difference
switches, the symbol ( ) appearing in the main display of the control
panel reminds of the need of servicing the unit. The reminder interval
can be set at 1...15 months. The factory setting is 4 months. This
function is always active.
The fault signal relay in the unit gives potential-free alarm indications
on the following fault conditions:
•

Alarm of high carbon dioxide content (> 5000 ppm) switches the

relay at 1-second intervals.

•

In other fault situations, such as sensor faults, the contacts of the

relay close.

Booster or fireplace switch function

The booster or fireplace switch function of the ventilation unit is controlled
either at control panel

and/or separate switch

, which can be

connected to the connection box of the unit. The mode of operation
of the switch is selected at control panel

. The booster switch function

raises fan speed to the set maximum fan speed for 45 minutes. The
fireplace switch stops the extract air fan for 15 minutes and produces
overpressure in the ventilation zone. LON remote monitoring control
can be implemented with a VALLOX LON converter. (See a separate
brochure.)

Voltage values
for each fan speed:

0.20...1.25 VDC

1.75...2.25 VDC

2 2.75...3.25 VDC

3 3.75...4.25 VDC

4 4.75...5.25 VDC

5 5.75...6.25 VDC

6 6.75...7.25

VDC

7.75...8.25 VDC

8 8.75...10.00

VDC