Art. No. SC 1000 KNX
4.2.4.3.3 Adapting the control algorithms
Adapting the PI control
There are several systems available, which may heat or cool 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 refrigerating
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 efficiently
control all common heating and cooling systems thus making the room temperature 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 significantly at times. For this reason, the room
temperature controller can be set to predefined ‘experience values’ for the most common
heating and cooling systems. In case the selection of a corresponding heating or cooling system
does not yield a satisfactory result with the default values, the adaptation can optionally be
optimized via control parameters.
Predefined control parameters for the heating or cooling level and, if applicable, also for the
additional levels 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 specified for heating and cooling
operation.
Type of heating Proportional
range (preset)
Reset time
(preset)
Recommended
PI control type
Recommended
PWM cycle time
Heat water
heating
5 Kelvin 150 minutes Continuous / PWM 15 min.
Underfloor heating 5 Kelvin 240 minutes PWM 15-20 min.
Electrical heating 4 Kelvin 100 minutes PWM 10-15 min.
Fan coil unit 4 Kelvin 90 minutes Continuous ---
Split unit (split
climate control unit)
4 Kelvin 90 minutes PWM 10-15 min.
Predefined control parameters and recommend control types for heating systems
Cooling type Proportional
range (preset)
Reset time
(preset)
Recommended
PI control type
Recommended
PWM cycle time
Cooling ceiling 5 Kelvin 240 minutes PWM 15-20 min.
Fan coil unit 4 Kelvin 90 minutes Continuous ---
Split unit (split
climate control unit)
4 Kelvin 90 minutes PWM 10-15 min.
Predefined control parameters and recommend control types for cooling systems
If the "Type of heating" or "Type of cooling" parameters are set to "Via control parameters" it will
be possible to adjust the control parameter manually. The feedback control may be
considerably influenced by presetting the proportional range for heating or for cooling (P
component) and the reset time for heating or for cooling (I component).
i Even small adjustments of the control parameters will lead to noticeable different control
behaviour.
Page 177 of 347
Software "Smart Control 501511"
Functional description
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