KNX Journal 2011-1

KNX System
KNX HVAC RF made easy
Energy Efficiency with KNX: new Easy channels for KNX RF based solutions
Window contact
Scheduler
Solar panels
Heat pump
Presence
Detector
At the 2008 edition of the ish
fair and when hearing about
the then new specification
for OpenTherm KNX RF
realizations, a group of HVAC
manufacturers joined forces
and set up a new Task Force.
The goal of the Task Force
was to extend the KNX specifications
in such a way that it
would be able to develop a fullfledged
KNX central heating
system, including hot water
production, influencing heat/
cool production depending on
the valve positions in individual
rooms and taking into account
systems like heat pumps and
solar panels.
As this application allows to
not only heat/cool rooms
individually but also informs
the producer of heat or cooling
on the current needs, it
contributes significantly to the
energy efficiency of homes and
buildings.
During the elaboration of
the extensions to the KNX
Standard, the Task Force
agreed that the solution should
enable the installer to set up
the system without the help
of a tool and that the solution
should permit devices to
communicate only wireless.
KNX RF and the KNX Easy
installation principle were
the natural consequence,
whereby it was agreed to take
into account the new KNX
flexible E-Mode concept. The
latter enables to develop Easy
compatible products, of which
the number of data points is
not rigidly fixed but extendible.
The agreed application has
now been published in the
KNX Application Note 138
and principally works as
follows:
- The core of the system
consists of a Room Regulator
and a Central Heating
Controller.
- The Room Regulator can
receive the necessary input
data from amongst
others a scheduler, window
contacts, a presence detector
and possibly a Room
and Outside temperature
sensor.
- On the basis of the above information,
the Room Regulator
controls the connected
heating or cooling valves.
- The application can be
extended with a Maximum
Position Selector, which
collects the valve positions
as sent by the available
Room Regulators. The
Maximum Position Selector
Room Regulator
Room / Outside
Temperature Sensor
Heat / Cooling Producer
then calculates the maximum
position and provides
this to the central heating
controller.
- The Central Heating Controller
may:
• receive the calculated
maximum position of the
installed valves;
• receive a shift/correction
of the central heating flow
temperature
• receive commands from
a connected heat pump, allowing
to turn off the central
heating system;
• receive commands from a
connected solar controller,
allowing turning off the
domestic hot water production;
Heating / Cooling valves
Pump
Heat meter
• inform a connected heat
meter on the actual consumed
heat
• influence the set point of
the revolution speed ration
of the connected heating
pump.
Next to the manufacturers
involved in the before-said
Task Force, members of KNX
are invited to start developments
on the basis of this
newly available extension to
the KNX specifications. More
information can be obtained
from the TF Chairman, Mr.
Joost Demarest (joost.demarest@knx.org
– 0032 2 775
86 44).
18 Journal 1/2011