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Siemens
RDU340… Basic Documentation
CE1P3078en
Building Technologies
Functions
2014-11-03
4.6.2
Single duct with electrical heater
If the selected application is "single duct & el. heater", then the controller works in
heating and cooling mode.
The output can be limited to a minimum and maximum value if required.
See section 4.5 "additional features".
In single duct applications with electrical heater, the controller controls an actuator
(valve, damper, VAV system, etc.) plus an auxiliary electrical heater.
Note: The setpoint for the electrical heater is limited by parameter “Maximum
heating setpoint” (P10).
Remote enabling/disabling of the electrical heater is possible via digital input X1/X2
for tariff regulations, energy saving etc.
Input X1 or X2 must be commissioned accordingly. See section “4.9 Multifunctional
input”.
The diagram below shows the control sequence for continuous PI control.
Cooling and heating with electric heater
TR[°C] Room temperature
Vmin Min. limitation for output
W
Room temperature setpoint
Vmax Max. limitation for output
Y10
Control
command
“actuator”
XpC Proportional band
“Cooling”
Y21
Control command “electrical heater”
Xdz Dead
zone
SDH Switching
differential
Note: The diagrams show the PI controller's proportional part only.
Single duct
with el. heater
Digital input “Enable
electrical heater”
Control sequence
