User Manual

9
3.3.2 tx2 control
Figure 3-3
tx2 control – Determination of the room setpoint and cascade control for temperature and absolute
humidity.
Both room temperature and humidity are controlled as follows using the
Economizer tx2:
The comfort area determines the room air setpoint for temparature and humidity
based on the present room air state and the defined comfort area. The comfort
area is not actively controlled. When elements are activated, control is exercised to
the field's limit.
The temperature and humidity controller are used as room air supply sequence
cascade controllers. The reference controller calculates the reference variable for
supply air from the room-side control deviation. The supply air controllers calculate
the positioning signals for heating, cooling, humidification and dehumidification
from supply air-side control deviations.
Defining the room setpoint
Economizer tx2 (Figure 3-3) identifies the best room setpoint at the border or within
the comfort area and applies optimized ERC (Figure 3-4).
Demand for heating, cooling, humidification, and dehumidification or a combination
thereof is based on the preconditioned air state and supply air setpoint.
– For "heating and humidification", "cooling and dehumidification" and
humidification and possible reheating", the related setpoint is identical to the
most energy-efficient corner point within the comfort area.
– For "cooling only", the setpoint is achieved by projecting the actual value to the
upper limit of the comfort area.
– For "heating only", projection is to the lower limit. The range with relative
humidity forming the limit represents a special case. Here, the temperature
setpoint is shifted along the relative humidity line. This results in greater heating