User manual

Operation
18
3.2.3 Chilled Water Control
The chilled water control valve is adjusted proportionally as the temperature control varies the
requirement for cooling from 0% to 100%.
Modulating actuators operate 2 or 3 way ball valves which are driven via 0-10VDC analogue outputs.
The Service Menu, Options Setup defines the various parameters necessary to operate the valves.
The Intelligent control algorithm is used to accurately control space conditions, whilst minimising
wear and tear on the actuators that is generally found in traditional control logic systems.
Figure 14 Modulating actuator control (example: cooling)
3.3 Temperature Control—Reheat
If the room air temperature becomes too cold, the control will call for heating. Heating mode is con-
trolled by the Temperature Proportional Band, explained in 3.2.1 - Temperature Proportional Band.
3.3.1 Electric Reheat
The Reheat Proportional Band is divided into three equal parts. As the Temperature Proportional
Band increases the call for heating from 0% to -100%, the reheat stages are switched On, as shown in
Figure 15. Note: PEX models are supplied with one stage heating as standard. Two stage is optional.
Figure 15 Electric staged heating
Requested
actuator position
Cooling
+ 100%
Cooling
0%
Setpoint
Increasing Temperature
0% - Closed
100% - Fully Open
1/2 Proportional Band
Decreasing Temperature
1/2 Proportional Band
Temp Setpoint: 21
o
C
Proportional Band: 4
o
C
Deadband: 1
o
C
2120.52019.51918.5
Heat 1
On
Heat 2
On
Heat 1
Off
Heat 2
Off
- 100%
Heating
0%
Heating
1/2 Deadband