Assortment / System Description

Heat pump application
Actuators
20
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20.12 Actuators
The DRX2 automation station controls heating/cooling valves via Triac and
analog outputs, regardless of available I/Os. 3-position actuators, thermal pulse
width modulation (PWM) actuators, PWM actuators with return spring can be
connected to the Triac outputs.
A maximum of 1 thermal valve can be connected to each Triac on the DXR2
automation station with AC 230 V power.
Conventional 0…10V actuators as well as 6-port valves can be connected to
analog outputs.
20.13 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
20.14 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.
20.15 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
Outside air temperature
dependent heating
curve