Siemens RDF20U User Manual

RDF20U
Technical Instructions
Document No. 155-334
September 27, 2007
Room Temperature Controller
with LCD for Two-Pipe Fan Coil
Units with Electric Heat
Siemens Industry, Inc.
Description
Room temperature controller with LCD for two-pipe fan coil units with electric heat.
Features
• Output for an on/off valve actuator
• Output for electric heat.
• Outputs for a three-speed fan.
• Control depending on the room or the return air temperature.
• Automatic heating/cooling changeover.
• 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:
• Control of the room temperature in individual rooms that are heated or cooled with
two-pipe fan coil units equipped with electric heat.
• Opening or closing a valve.
• Switching electric heat.
• Switching a three-speed fan.
Suitable for two-pipe fan coil unit systems with:
• Automatic heating/cooling changeover.
• Continuous heating or cooling mode.
Product Number
RDF20U

Siemens RDF20U Specifications

General

Brand	Siemens
Model	RDF20U
Category	Temperature Controller
Language	English

Summary

Accessories

Warning/Caution Notations

Operation

Fan Operation

Details fan switching based on temperature and operating modes.

Display

Explains how the controller displays temperature or setpoint based on DIP switch settings.

Water-based Fan Coil Application

Heating Mode

Describes valve control logic for heating mode based on room temperature and setpoint.

Cooling Mode

Describes valve control logic for cooling mode based on room temperature and setpoint.

Automatic Changeover

Explains switching between heating/cooling based on water temperature.

Automatic Changeover, Continued

Purging Function (Optional)

Details optional purging function for correct medium temperature acquisition.

Return Air Temperature (Optional)

Explains operation based on return air temperature sensor.

Electric Heat, Active in Heating Mode

Describes ON/OFF command logic for electric heat during heating.

Electric Heat, Active in Cooling Mode

Describes ON/OFF command logic for electric heat during cooling.

Operating Modes

Normal Mode

Controller maintains setpoint with auto changeover and manual fan speed.

Economy Mode

Operating mode changes to Economy via input, maintaining setpoints.

Standby

Relevant setpoints maintained in Standby mode; specific temperature settings available.

Setting the Control Parameters

Avoiding Damage Due to Moisture (continuous fan)

Ensures fan runs to avoid moisture damage in humid climates.

Ordering

Mechanical Design

Setting and Operating Elements

Engineering Notes

Mounting, Installation and Commissioning Notes

Calibrating the Sensor

Specifications

Operational Data

Specifications (Continued)

Environmental Conditions

Details transport and storage temperature and humidity ranges.

Agency Approvals

Lists agency approvals, such as UL Listing.

General

Covers connection terminals, weight, and housing front color.

Wiring Terminals

Wiring Diagrams

Dimensions In Inches (Millimeters)