User Manual

29
AUTOMATIC CONTROL
1 HEATING CONTROL BT Reason for energy savings
1.2 Emission control of TABS (heating mode) 5
0
No automatic control of the room temperature The highest supply output is continuously
delivered to the TABS, resulting in the supply of
unnecessary thermal energy under part load
conditions.
1
Central automatic control
The central automatic control for a TABS zone
(which comprises all rooms which get the same
supply water temperature) typically is a supply
water temperature control loop whose set-point is
dependent on the filtered outside temperature,
e.g. the average of the previous 24 hours.
6
Supply output is controlled depending on the
outside temperature, for example
(corresponding to the probable heat demand of
the consumers). Energy losses under part load
conditions are reduced, but no advantage can
be taken of individual heat gains in the rooms.
2
Advanced central automatic control
This is a central automatic control of the TABS
zone that is designed and tuned to achieve an
optimal self-regulating of the room temperature
within the required comfort range (specified by the
room temperature heating set-point). “Optimal”
means that the room temperatures of all rooms of
the TABS zone remain during operation periods in
the comfort range, to meet comfort requirements,
but also is as low as possible to reduce the energy
demand for heating.
7
Supply output is controlled depending on the
outside temperature, for example
(corresponding to the probable heat demand of
the consumers).
Taking advantage of self-regulating effects
during operating times fulfills comfort
requirements in all the rooms and reduces heat
demand as much as possible.
Different setpoints for heating and cooling (e.g.
through the use of a setpoint range for the flow
temperature) can prevent unnecessary
overheating or undercooling. Additional energy
can be saved by compensating for known heat
gains in the building (e.g. by adjusting the flow
temperatures over the weekend in office
buildings – if there are no internal heat gains).
Within a specified outside temperature range
(transition period), the changeover between
heating and cooling occurs (indirectly) based
on heat gains in the building. This may
enhance comfort and automate operation (no
need for the operator to manually change
over).
3
Advanced central automatic control with
intermittent operation and/or room temperature
feedback control:
a) Advanced central automatic control with
intermittent operation. This is an advanced
central automatic control according to 2) with
the following supplement: The pump is
switched off regularly to save electrical energy,
either with a fast frequency - typically 6 hours
on/off cycle time - or with a slow frequency,
corresponding to 24 hours on/off cycle time. If
the TABS is used for cooling, intermittent
operation with 24 hours on/off cycle time can
also be used to reject the heat to the outside
air if the outside air is cold.
b) Advanced central automatic control with room
temperature feedback control. This is an
advanced central automatic control according
to 2) with the following supplement: The
supply water temperature set-point is
corrected by the output of a room temperature
feedback controller, to adapt the set-point to
non-predictable day-to-day variation of the
heat gain. Since TABS react slowly, only day-
to-day room temperature correction is applied,
an instant correction cannot be achieved with
TABS. The room temperature that is fed back
is the temperature of a reference room or
another temperature representative for the
zone.
c) Advanced central automatic control with
intermittent operation and room temperature
feedback control
Even more electricity can be saved through
pump cycling operation. In addition, the on
phases can be executed in some cases if
energy efficiency can be gained or at times
when energy is available at lower rates (e.g.
cooling at night at low outside temperatures or
at lower rates).
Heat gains can be used to save energy through
the use of room temperature control in a
reference room by readjusting the flow
temperature setpoint. Room temperature
control automates the compensation of
additional or missing heat gains and, if required
corrects incorrectly set weather-compensated
control in a restricted range.