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Room temperature controller | Room temperature controller - General
Advantages:
This setting ensures continuous water flow through the radiators, thus facilitating uni-
form heat emission into the room.
If only one valve drive is triggered the controller can continuously adapt the com-
mand value to compensate the mean value shift caused by the short cycle time, thus
setting the desired room temperature.
Disadvantages:
If more than one drive is triggered at the same time the desired mean value will be-
come the command value, which will result in a very poor adjustment of the required
room temperature, or in adjustment of the latter with major deviations, respectively.
The continuous flow of water through the valve, and thus the continuous heating of
the drives causes changes to the dead times of the drives during the opening and
closing phase. The short cycle time and the dead times means that the required com-
mand value (mean value) is only set with a possibly large deviation. For the room
temperature to be regulated constantly after a set time, the controller must continu-
ally adjust the command value to compensate for the mean value shift caused by the
short cycle time. Usually, the control algorithm implemented in the controller (PI con-
trol) ensures that control deviations are compensated.
This setting is recommended for quick-reaction heating systems (such as sur-
face radiators).
Adapting the PI control
In a building, different systems can be installed which heat up or cool down a room.
One option is to uniformly heat or cool the surroundings via heat transfer media
(preferably water or oil) in connection with room air convection. Such systems are
used, for example, with wall mounted heaters, underfloor heating or cooling ceilings.
Alternatively or additionally forced air systems may heat or cool rooms. In most cases
such systems are electrical forced hot air systems, forced cool air systems or refriger-
ating compressors with fan. Due to the direct heating of the room air such heating
and cooling systems work quite swiftly.
The control parameters need to be adjusted so that the PI control algorithm may effi-
ciently control all common heating and cooling systems thus making the room tem-
perature control work as fast as possible and without deviation. Certain factors can
be adjusted with a PI control that can influence the control behaviour quite signific-
antly at times. For this reason, the room temperature controller can be set to pre-
defined control parameters for the most common heating and cooling systems. In
case the selection of a corresponding heating or cooling system does not yield a sat-
isfactory result with the default values, the adaptation can optionally be optimised us-
ing control parameters.
Predefined control parameters for the heating or cooling stage and, if applicable, also
for the additional stages are adjusted via the "type of heating" or "type of cooling"
parameters. These fixed values correspond to the practical values of a properly
planned and executed air conditioning system and will result in an ideal behaviour of
the temperature control. The heating and cooling types shown in the following tables
can be set for heating and cooling operation.
Heating actuator 6-gang with controller | Order no. 2139 00 | 21393100
Page 128 of 257
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