Assortment / System Description

Ceiling heating/chilled ceiling application
Valve protection
16
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16.7 Valve protection
Valve actuators are operated from time to time to prevent them from seizing
after long periods of inactivity (e.g. heating valve during the summer). The valve
actuator is controlled to lose as little heating energy as possible.
The central function for the hot water supply chain performs the valve
protection function and can be changed in the parameters as needed.
Description Name Default value
Kick value KickVal 50 [%]
Kick time TiKick 2 min
Kick cycle KickCyc 500 h
16.8 Determination of heating/cooling state
All DXR2 applications analyze heating/cooling state by comparing the present
room temperature against the setpoints and active control sequence. The
present state is displayed on the room operator unit and the BAC system.
A sequence controller prevent simultaneous heating/cooling.
16.9 Heating/cooling demand
Each DXR2 automation station calculates heating and cooling demand for a
room and makes the result available through a group of the central function
(supply chain hot water/chilled water).
The hot water demand setpoint is calculated in the central function using a
heating curve based on the outside temperature.
Sp Flow temperature setpoint TOa Outside air temperature
SpTFlDs 70 °C TOaDs -11 °C
SpTFlHi 25 °C TOaHi 15 °C
Figure: Characteristic curve for the outside temperature-dependent heating
curve
Valve positions in the various rooms correct the demand setpoint in the central
function based on the number of valves between a value of 70...100%.
Description Name Default value
Setpoint correction, if 100% of all consumers are
within 70…100%.
SpCorrTFlHi 5 [K]
Setpoint correction, if 0% of all consumers are within
70…100%.
SpCorrTFlLo -5 [K]
Outside air temperature
dependent heating
curve
Demand correction by
collected valve
positions