Assortment / System Description

Radiator application

Determination of heating/cooling state

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The downdraft compensation functions slows down sinking cold air current at

large window surfaces and prevents in this manner a cold wall effect on large,

cold surfaces. The function activates the radiator if the outside temperature

drops below a configured value by increasing the minimum radiator control to a

higher value. A linear reset function implements the downdraft compensation.

The control sequence is only active in the Comfort room operating mode. The

following graphic provides the factory settings for the downdraft compensation

parameters.

Y Output signal TOa Outside air temperature

Y1 100 % X1 -5 °C

Y2 0 % X2 10 °C

Figure: Downdraft compensation characteristic curve

14.3 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.

14.4 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

Downdraft

compensation

Outside air temperature

dependent heating

curve