Danfoss RESD Series - User Manual

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RESD Series Electronic Thermostat User Manual

RESD series thermostat adopts a button-hidden fashion appearance design. It

is used to control temperature for light industry, commercial and residential

environments. Models are available for heating, cooling and ventilating control. The

application is for the control of Fan Coil heating/cooling equipment.

RESD series thermostats are microprocessor controlled and have a big LCD

display, which displays the current working state (cooling, heating, ventilating), fan

speed, ambient temperature, setting temperature etc. pushbutton includes turn on/off

(

), mode ( ), clock (



), fan speed (

) and temperature adjustment ( 

 ).

MODEL DENOMINATIONS

BASIC FEATURES STATUS DISPLAY



Room temperature setting



Manual or Auto 3-speed changeover



Defrost (low temperature protection)



Clock, Timer

7 days programmable (-T74)



Blue backlight



Auto Restart ( Option )



Keypad Lock ( Option )



Working Status: Cool , Heat , Ventilation



Fan Speeds: Low , Medium , High and Auto



Room temperature display



Temperature setting display



FCU valve



Clock week display

SPECIFICATIONS

 Sensing element: NTC

 Accuracy: Temperature ± 1°C Time ± 1 min/month

 Set-point range: 5 to 35°C

 Display range: 0 to 55°C

 Operation environment: T min 0°C T max 45°C)

 Power supply: 85 to 260V~, 50/60Hz

 Switch current rating: Resistive: 2 A, Inductive: 1 A

 Switching action Type 1B

 Control pollution degree 2

 Rated impulse V 2.5kV

 Ball Hardness 75°C

 Power reserve 24 hrs minimum

 Setting accuracy ±0.5°C ±1 minute

 Rated Power: < 1 W

 Wirings: Screw-in terminals, each terminal capable of

accepting 2 × 1.5 mm

or 1 x 2.5 mm

wires

 Housing: PC + ABS Flame Retardant

 Dimensions: 86 × 86 × 13 mm ( W × H × D )

 Hole pitch: 60 mm ( Standard )

 Protection Class: IP30

 Display: LCD

RESD -

HC2: Control Motorized Valve and 3-speed fan. When the temperature reaches the set-point, it will close the

Motorized Valve and Fan both.

HC4: Control 4 pipe fan coil units, Control two Motorized Valves and 3-speed fan. When the temperature reaches the

set-point, it will close the Motorized Valve and Fan both.

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Summary

RESD Series Electronic Thermostat User Manual

Model Denominations

Differentiates HC2 and HC4 models for fan coil control applications.

Basic Features

Lists core functionalities like temperature setting, fan control, defrost, and clock.

Specifications

Details technical specifications including sensing element, accuracy, power, and dimensions.

Status Display

Explains the information shown on the thermostat's LCD screen.

Operation

On;Off and Temperature Setting

Instructions for powering the device and adjusting the target temperature.

Mode Selection

How to choose between cooling, heating, and ventilation modes.

Fan Speed Control

Guide to selecting fan speed: Low, Medium, High, and Auto.

Clock Calibration

Procedures for setting the current time and date accurately.

Timer Functions

Steps to set, modify, and cancel timer schedules for operation.

Advanced Features

7 Days Programming

Detailed guide for setting up four daily events with start times and temperatures over seven days.

Keypad Lock

How to enable and disable the keypad lock feature for security.

Auto Restart

Explains the thermostat's behavior and status after a power interruption.

Defrost (Low Temperature Protection)

Details the function that activates heating to prevent freezing.

Alarm Codes

Information on error indicators (E1, E2) and temperature alerts (HI, LO).

Installation

Opening the Clip

Step 1: Instructions on how to open the thermostat's retaining clip.

Wiring Connections

Step 2: Guide for correctly connecting the electrical wires to the thermostat terminals.

Securing the Thermostat

Step 3: How to mount the thermostat firmly to the wall using screws.

Final Assembly

Step 4: Process for attaching the thermostat surface and completing the installation.

Installation Attention

Important safety and maintenance notes for proper installation and device protection.

The Danfoss RESD Series Electronic Thermostat is a microprocessor-controlled device designed for temperature regulation in light industry, commercial, and residential settings. Its modern design features a hidden button interface and a large LCD that displays the current operating status, including cooling, heating, ventilation modes, fan speed, ambient temperature, and set temperature. The device is suitable for controlling Fan Coil heating/cooling equipment.

Function Description

The thermostat controls motorized valves and a 3-speed fan. The HC2 model manages one motorized valve and a 3-speed fan, closing both when the temperature reaches the set-point. The HC4 model is designed for 4-pipe fan coil units, controlling two motorized valves and a 3-speed fan, also closing both when the set-point is met.

Important Technical Specifications

Sensing Element: NTC
Accuracy: Temperature ± 1°C, Time ± 1 min/month
Set-point Range: 5 to 35℃
Display Range: 0 to 55℃
Operation Environment: T min 0℃, T max 45℃
Power Supply: 85 to 260V~, 50/60Hz
Switch Current Rating: Resistive: 2 A, Inductive: 1 A
Switching Action: Type 1B
Control Pollution: Degree 2
Rated Impulse Voltage: 2.5kV
Ball Hardness: 75℃
Power Reserve: 24 hours minimum
Setting Accuracy: ±0.5℃, ±1 minute
Rated Power: < 1 W
Wirings: Screw-in terminals, each capable of accepting 2 x 1.5 mm² or 1 x 2.5 mm² wires
Housing: PC + ABS Flame Retardant
Dimensions: 86 x 86 x 13 mm (W × H × D)
Hole Pitch: 60 mm (Standard)
Protection Class: IP30
Display: LCD

Usage Features

The thermostat offers several user-friendly features:

Room Temperature Setting: Users can easily adjust the desired room temperature.
Manual or Auto 3-speed Changeover: The fan speed can be manually selected or set to automatic mode. In auto mode, the fan speed changes based on the difference between room temperature and set temperature: low speed when the difference exceeds 1°C, medium speed when it exceeds 2°C, and high speed when it exceeds 3°C.
Defrost (Low Temperature Protection): This feature automatically turns on the heating mode with the fan running at high speed if the room temperature drops below 5°C, turning off when it rises above 7°C. This function can be enabled or disabled.
Clock, Timer, 7 Days Programmable (-T74): The device includes a real-time clock and a 7-day programmable timer with four events per day, allowing users to set specific start times and temperatures for each event.
Blue Backlight: Provides clear visibility of the display in various lighting conditions.
Auto Restart (Option): If enabled, the thermostat will resume its previous operating status (from one minute before power loss) after a power cut, provided it was in the ON state for at least 6 seconds prior to the outage. If it was OFF for 6 seconds, it will remain OFF.
Keypad Lock (Option): After 30 seconds of standby, the keypad can automatically lock to prevent unintended operation. It can be unlocked by pressing a specific button for 5 seconds.
Status Display: The LCD shows the working status (cool, heat, ventilation), fan speeds (low, medium, high, auto), room temperature, set temperature, FCU valve status, and clock/week display.
Mode Selection: Users can select cooling, heating, or ventilation modes, with the selected icon flashing for 6 seconds before confirmation.
Temperature Adjustment: Temperature can be adjusted in 0.5°C increments.
Override Function: When the 4-period function is active, adjusting the set-point will activate "Override" mode, causing the thermostat to run according to the current setting instead of the programmed schedule.

Maintenance Features

Alarm System: The thermostat includes an alarm system that indicates issues with the sensor, fan, or valve. "E1" signifies a short circuit in the sensor, while "E2" indicates an open circuit. "HI" is displayed if the temperature exceeds 55°C, and "LO" if it falls below 0°C. In case of an alarm, the fan and valve will be turned off.

Installation

Installation requires a standard electrical box. Wiring must be performed according to the provided wiring diagram. It is crucial to keep water, mud, and other impurities out of the thermostat to prevent damage. The installation process involves opening a clip, wiring the device, fixing it with two bolts, and then locking the surface cover.