Siemens RDF30U Technical Instructions

RDF30U

Technical Instructions

Document No. 155-335

September 27, 2007

Room Temperature Controller
with LCD for Four-Pipe Fan
Coil Units

Siemens Industry, Inc.

Description

Room temperature controller with LCD for four-pipe fan coil units.

Features

• Outputs for separate, heating and cooling on/off valve actuators.

• Outputs for a three-speed fan.

• Control depending on the room or the return air temperature.

• Operating modes: Normal, Economy and Standby.

• Operating mode changeover input for remote control (Day/Night).

• Air movement control function for avoiding damage resulting from moisture.

• Selectable installation and control parameters.

• Display of room temperature or setpoint (selectable).

• Electronic minimum and maximum setpoint limits.

• Operating voltage 24 Vac.

Application

Typical use:

• For controlling room temperature in individual rooms that are heated or cooled with

four-pipe fan coil units.

• For opening or closing two valves and for switching a three-speed fan.

Suitable for four-pipe fan coil unit systems with:

• automatic heating/cooling changeover.

• continuous heating or cooling mode.

Product Number

RDF30U

Technical Instructions RDF30U Room Temperature Controller with LCD
Document Number 155-335 for Four-Pipe Fan Coil Units
September 27, 2007

Page 2 Siemens Industry, Inc.

Accessories

ARG70 Adapter plate for 4-inch × 4-inch or 2-inch × 4-inch conduit boxes
141-570 Lockable thermostat guard
QAH11.1 Changeover/remote temperature sensor

Warning/Caution
Notations

WARNING:

Personal injury or loss of life may occur if you do not perform
a procedure as specified.

CAUTION:

Equipment damage may occur if you do not follow a
procedure as specified.

Operation

The controller acquires the room temperature via its integrated sensor or optional
external return air temperature sensor (QAH11.1) and maintains the setpoint by
delivering two-position valve control output commands.

The switching differential is 2 K (3.6F) in Heating mode (adjustable in Parameter 10)
and 1 K (1.8F) in Cooling mode (adjustable in Parameter 11).

Fan Operation

The fan is switched to the selected speed via control output 12, 11 or 10.
When the “Temperature-dependent fan control“ function is activated (can be selected

with DIP Switch No. 1), the fan is switched on/off depending on the temperature,
together with the valve. It is switched off when any of the following occurs:

• leaving the heating or cooling sequence, provided the “Temperature-dependent fan

control“ function is activated.

• manually changing to Standby provided no setpoints (example, for freeze

protection) are set and active.

• activating an external operating mode changeover switch, provided application

conditions do not call for Economy mode.

• turning off the controller’s power supply.

Display

If DIP Switch No. 2 is set to ON (factory setting), the controller displays the measured
room or return air temperature (unless parameters or setpoints are temporarily
changed). If the DIP switch is set to OFF, the controller displays the Normal operating
mode setpoint. In this case, the value of the current temperature reading can only be
visualized temporarily by selecting Parameter P14.

Water-based Fan Coil
Application (Heating
mode)

When used in connection with four-pipe fan coils set DIP Switch No. 4 to ON.
Use in conjunction with two valves, for heating and cooling operation.

Heating Mode
Terminals 4 and 2 (neutral) or 5 and 2 command the control valve.

Output terminals 4 and 2 are closed (24 Vac) when:

1. the measured room temperature is half the switching differential below the setpoint
(W, Heating mode), and

2. the valve has been closed for more than one minute (Parameter P20).

Output terminals 4 and 2 are open (0 Vac) when:

1. the measured room temperature is half the switching differential above the setpoint
(W, Heating mode), and

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 Standby “ ”
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".