RDF30U Room Temperature Controller with LCD
Technical Instructions
For Four-Pipe Fan Coil Units
Document Number 155-335
September 27, 2007
Siemens Industry, Inc.
Page 3
2. the valve has been open for more than one minute (Parameter 19)
NOTE:
Output terminals 5 and 2 are the inverse of terminals 4 and 2.
Cooling Mode
Output terminals 6 and 2 (neutral) are open (0 Vac) when:
1. the measured room temperature is at half the switching differential below the
Cooling mode setpoint (W + Xdz
– 1/2 SDC), and
2. the valve has been open for more than one minute (Parameter P19).
Output terminals 6 and 2 (neutral) are closed (24 Vac) when:
1. the measured room temperature is at half the switching differential above the
Cooling mode setpoint (W + Xdz + 1/2 SDC), and
2. the valve has been closed for more than one minute (Parameter P20).
T
Room temperature
SDH Switching differential, Heating
SDC Switching differential, Cooling
Xdz
Dead zone
w
Room temperature setpoint
YH
Heating valve, 24 Vac control output
YC
Cooling valve, 24 Vac control output
Figure 1. Water-based Fan Coil
Heating and Cooling Mode.
Return Air Temperature
(Optional)
The RDF30U provides control based on the measured room temperature or the fan coil
unit’s return air temperature. It detects if a QAH11.1 cable temperature sensor is
connected to input 9-8 and then operates automatically according to that temperature.
Operating Modes
Normal Mode
Heating or Cooling mode with automatic changeover and manually selected fan speed
(III, II or I). In Normal mode, the controller maintains the adjusted setpoint in Heating
mode and; in Cooling mode, a temperature level represented by the setpoint plus the
dead zone.
Economy Mode
A potential-free operating mode changeover switch can be connected to status input
D1-GND. When the switch closes its contact (due to an open window, for instance), the
operating mode will change from Normal to Economy. In this operating mode, the
relevant setpoints of heating or cooling are maintained (adjustable in Parameters P01
[setback temperature for heating] and P02 [setback temperature for cooling]). The
operating action of the switch (NC or NO) can be selected.
Standby
The relevant setpoints of heating and cooling are maintained when in Standb
y “ ”
mode, provided those setpoints have been adjusted. The standby temperature setting
for Heating mode in Parameter P03 is adjustable from 41°F to 68°F (5°C to 20°C) or
“OFF” and the setting for Cooling mode in Parameter P04 is adjustable from 70°F to
95°F (21°C to 35°C) or "OFF".
