HVAC APPLICATIONS
HVAC APPLICATIONS
The VAV (Variable Air Volume) systems are designed for room ventilation according
to the actual needs, having inside the appropriate boxes (2) motorized dampers (1)
that act as a regulator of the fresh air flow. In combination with the home automation
sensors installed in the room, the system guarantees high energy efficiency, since the
room can be ventilated according to one or more parameters measured in the room.
The use of an EK-TM1-TP time digital switch (A), possibly with optional GPS module
(B), allows not only to define the operating time scheduling for the ventilation system
according to the expected occupation of the building, but also advanced functions like,
for example, the activation of a washing cycle of the room air before the beginning of
working hours.
The use of a presence sensor EK-DF2-TP (D) is indicated when you want to make
an automatic control of simplified type with opening of the damper of the VAV box in
conditions of occupied room and setting the minimum flow rate to save energy when
the room is not occupied. Higher efficiency is achieved by using a multisensor (C) that
can adjust the flow rate of incoming air according to the measurement of air quality and
the predefined thresholds.
The signal of a window contact (5), detected by an input interface EK-CC2-TP (E), allows
to temporarily deactivate the ventilation so as not to waste unnecessarily energy; the
reactivation takes place automatically when the window is closed.
Control based on CO2 or TVOC values
The choice of the control parameter depends mainly on the intended use of the rooms.
Where the variability in the occupancy rate is very high or unpredictable (such as
in meeting rooms, classrooms or small commercial environments) CO2 is the most
used indicator because its concentration is directly related to human activity and,
in particular, to breathing. Although CO2 is not harmful to human health (except in
very high concentrations, which are difficult to achieve), it has a direct impact on the
concentration capacity and productivity of the occupants. When the number of people
in the room is predictable and limited, the detection of volatile organic compounds (or
TVOC), a set of organic chemicals continuously emitted from furniture, paints, cleaning
solvents, adhesives or other synthetic materials due to their high volatility, may be more
significant.
Air renewal with VAV boxes
Air extraction
Air supply
M
M
1
1
2
2
3
4
5
EK-TM1-TP
Digital time / Astronomical switch
A
B
C
D
E
Example
Ekinex devices
A) Time / astronomical digital switch EK-TM1-TP
B) GPS module EK-GPS-1
C) Multisensor EK-ET2-TP
D) Presence sensor EK-DF2-TP
E) Universal interface EK-CC2-TP
Other system components
1) KNX servomotor for dumper (not delivered by Ekinex)
2) VAV (Variable Air Volume) box
3) Air supply outlet
4) Air extraction outlet
5) Window contact
The high level of insulation and the high-performance windows and doors used in new
buildings or in buildings that have undergone major renovation to meet the energy
efficiency requirements of EPBD directive (91/2002/EC and following releases) have
greatly reduced heat losses to the outside and, at the same time, have in many cases
made it necessary to use mechanical ventilation units for air renewal with energy
recovery. The manual control of these units alone is inadequate to ensure energy
efficiency in their operation and even a simple time scheduling is not fully satisfactory.
As pointed out by EU Regulations no. 1253 and 1254 of 2014, for these ventilation
units it is necessary to use an environmental control by measuring one or more
parameters to automatically adjust the flow of fresh air to be introduced into the rooms.
Control with Ekinex
The EK-ET2-TP multisensor (D) measures three environmental parameters that are
representative of the ventilation requirement: the main one is the air quality (as CO2
concentration in ppm), together with the relative humidity (in %) and the temperature
(in °C). Other useful environmental parameters are the detection of the presence or
movement of people inside the rooms by means of the EK-DF2-TP sensor (E) or
signals due to the activation of other home automation functions, such as lighting
switching by means of the pushbutton (F) of 20venti series. The EK-TM1-TP (B) digital
time / astronomical switch (B) also provides start / stop command for the ventilation
system according to predefined time scheduling and is constantly synchronised with the
date and time by the (optional) GPS module EK-GPS-1 (C).
The EK-BO1-TP-RMA interface (A) for RDZ mechanical ventilation units with energy
recovery provides bidirectional communication between KNX devices and the control
board (2) of the unit. The EK-CC2-TP universal interface (G) acquires signals from
traditional components, such as a manual switch for seasonal changeover (3) or a
window contact (4).
Demand controlled ventilation
Thanks to the many environmental parameters made available by the Ekinex® home
automation system, it is possible to carry out ventilation control according to the actual
need for air renewal (a strategy known as DCV or Demand Controlled Ventilation). This
allows to constantly adjust the air flow rate to be introduced into the rooms to the
real needs with the aim of maintaining a constantly high air quality, while minimizing
the energy consumption. Air quality can typically be controlled by measuring the CO2
concentration. With this kind of control, energy savings are twofold: the operating time
of the fan units is reduced and the flow rate of fresh air to be handled, before release
into the rooms, through heating, cooling, humidification and dehumidification processes.
Air renewal with energy recovery ventilation units
General consensus
(EK-TM1-TP)
Temperature
Air quality
Relative
humidity
Presence
of people
Manual
control
Other
(EK-ET2-TP)
(EK-ET2-TP)
(EK-ET2-TP)
(EK-Dx2-TP)
(EK-E12-TP)
Ventilation
system
Additional information from ekinex KNX devices
(communicating real needs)
Domotic system (environmental parameters)
EK-TM1-TP
Digital time / Astronomical switch
B
C
TVOC
CO2
traffic
R
Error
Modbus / KNX interface for
RDZ air handling units
EK-BO1-TP-RMA
Modbus
Power
RX
TX
green
red
A
B
KNX
Progr.
RS-485 Modbus
A
D
E
F
COMFORT
OFF
ECONOMY
BOOST
G
3
4
1
2
5
6
8
7
Example
6
7
6
7
5
1
8
Ekinex devices
A) Modbus / KNX interface for RDZ air renewal units
B Time / astronomical digital switch EK-TM1-TP
C) GPS module EK-GPS-1
D) Multisensor EK-ET2-TP or EK-ES2-TP
E) Presence sensor EK-DF2-TP
F) Pushbutton Serie 20venti
G) Universal interface EK-CC2-TP
Other components
1) Mechanical ventilation unit with energy recovery
2) Control board of RDZ ventilation unit
3) Two-position switch
4) Window contact
5) Fresh air (from outside)
6) Stale air (from inside)
7) Pre-heated air (to inside)
8) Exhaust air (to outside)
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