RS PRO 326820 Multifunction Digital Thermostat
Product Overview
The RS PRO 326820 is a multifunction digital thermostat featuring a built-in time switch clock with day, week, and year programming capabilities. It allows for real-time temperature function and course adjustments. The thermostat offers a complex home and water heating, solar heating, and more. It can function as two independent thermostats, a dependent thermostat, a differential thermostat, a two-level thermostat, a zone-based thermostat, or a dead-zone thermostat.
Key features include monitoring for short circuits or sensor disconnection, program setting of output functions, and sensor calibration according to reference temperature (offset). The thermostat operates within a wide temperature range of -40 to 110°C and features a clear, backlit LCD display for set and measured data. It supports various switching modes: AUTO (automatic switching based on program), PROGRAMME (switching based on astro or time), RANDOM (random switching within a 10-120 minute interval), HOLIDAY (holiday mode to block timer functions), and MANUAL (manual control of individual output relays).
The device supports automatic switching programs like TER (switches based on temperature sensors and functions) and TIME PROGRAM (switches or sets temperature according to time program). It offers 100 memory locations for time programs (common for both channels) and can be programmed under voltage or in backup mode. The relay outputs do not function in backup mode. The menu display can be set to multiple languages, including English (EN), Czech (CZ), Russian (RU), Hungarian (HU), Spanish (ES), and Polish (PL).
The thermostat includes automatic daylight savings time transition according to time zone and has a backlit LCD display. It is easy to set using four control buttons and features a pluggable transparent cover on the front panel. The time switch clock has a battery backup (CR2032) for data retention during power outages, with a reserve backup time of up to 3 years. Power is supplied via AC 230V or 24V AC/DC, and it is designed for DIN rail mounting (2-module).
Technical Specifications
| Parameter | Value |
|---|---|
| Supply Terminals | A1 - A2 |
| Supply Voltage | AC 230 V (AC 50-60 Hz) or AC/DC 24 V |
| Consumption | max. 4 VA / 0.5 W |
| Max. Dissipated Power | 3 W |
| Supply Voltage Tolerance | -15%; +10% |
| Backup Battery Type | CR 2032 (3V) |
| Measuring Circuit Terminals | T1-T1 and T2-T2 |
| Temperature Range | -40..+110 °C |
| Hysteresis (Sensitivity) | Adjustable within range 0.5...5 °C |
| Difference | Adjustable 1.. 50 °C |
| Sensor | Thermistor NTC 12 kΩ at 25 °C |
| Sensor Failure Indication | Displayed on LCD |
| Measuring Accuracy | ±5% |
| Repeat Accuracy | < 0.5 °C |
| Temperature Dependance | < 0.1% / °C |
| Number of Functions | 6 |
| Number of Contacts | 1x switching for each output (AgNi) |
| Rated Current | 8 A/AC1 |
| Switching Capacity | 2000 VA/AC1, 240 W/DC |
| Switching Voltage | 250 V AC/30 V DC |
| Output Indication | Symbol ON/OFF |
| Mechanical Life | 1x10⁷ |
| Electrical Life (AC1) | 1x10⁵ |
| Real Time Back-up | Up to 3 years |
| Accuracy (Time) | max. ±1s/day at 23°C |
| Minimum Interval | 1 min. |
| Data Stored For | min. 10 years |
| Number of Memory Places (Programs) | 100 |
| Program Data Readout | Daily, Weekly, Yearly, LCD display with backlight |
| Operating Temperature | -10..+55 °C |
| Storage Temperature | -30.. +70 °C |
| Electrical Strength | 4 kV (supply - output) |
| Operating Position | Any |
| Mounting | DIN rail EN 60715 |
| Protection Degree | IP40 (front panel) / IP20 (clips) |
| Overvoltage Category | III. |
| Pollution Degree | 2 |
| Max. Cable Size | max. 1x 2.5, max. 2x 1.5 / with sleeve max. 1x 2.5 |
| Dimensions | 90 x 35 x 64 mm |
| Weight | (230V) 150 g, (24V) 113 g |
| Standards | EN 61812-1; EN 61010-1; EN 60730-2-9; EN 60730-1; EN 60730-2-7 |
Thermostat Functions Explained
The thermostat supports six distinct functions, each with specific operational characteristics:
- 1. 2 Independent Single-Stage Thermostats: Two separate thermostats operate independently, each controlling its own output (15-18 for T1, 25-28 for T2) based on its respective temperature settings and hysteresis.
- 2. Dependent Functions of 2 Thermostats: Output 15-18 is closed when both thermostats' temperatures are below an adjusted level. The contact opens when either thermostat reaches its set level. This functions as a logical AND operation between the two thermostats.
- 3. Differential Thermostat: Used to maintain two identical temperatures, such as in heating systems or solar systems. The output switches based on the difference between measured temperatures and a set difference value.
- 4. 2-Stage Thermostat: Suitable for applications like boiler rooms with a main and auxiliary boiler. It manages a primary boiler based on set temperature and activates a secondary boiler when the temperature drops below a set difference.
- 5. Thermostat with "WINDOW": The output is closed (heating) only if the temperature is within an adjusted range. If the temperature falls outside this range, the contact opens. This is useful for protecting gutters from freezing.
- 6. Thermostat with Dead Zone: Allows setting a temperature T1 and a dead zone width (D). For cooling, the output switches ON if the temperature is higher than T1 and OFF if it drops below T1. For heating, the output switches ON if the temperature is below T and OFF when T is exceeded. This maintains temperature within a specific range.
Mode Precedence
The device prioritizes operating modes as follows:
- Manual Control
- Holiday Mode
- Time Program (Prog)
- Thermostat (TER)
Note: TER and TIME PROGRAM can operate simultaneously on a single channel.
Control Description
The device features intuitive control using buttons for navigating menus, setting values, and confirming actions. Specific button presses (short <1s, long >1s) trigger different functions. After 30 seconds of inactivity, the device automatically returns to the starting menu. The display can be toggled between date and measured temperature by pressing a button on the start screen.
Language Settings
The thermostat supports multiple languages for its interface, including English (EN), Czech (CZ), Russian (RU), Hungarian (HU), Spanish (ES), and Polish (PL). The language can be selected through the settings menu.
Temperature Sensor
The device utilizes an NTC thermistor sensor (12 kΩ at 25°C) for temperature measurement. The resistance values vary with temperature, as detailed in the technical specifications. The tolerance of the sensor is ±5% at 25°C.
Programming and Settings
Time and Date Setting
Users can set the current time and date, including year, month, day, hour, and minute. The device also supports setting the switch between summer and winter time based on regional standards (e.g., EUR, USA, RUS). Date and time formats can also be customized.
Time Program
The thermostat allows for the creation and management of time programs. Users can add, edit, or delete daily and yearly programs. Each program can define specific time intervals, temperature settings, or constant ON/OFF states for the outputs. The device has memory for 100 programs.
Switching Modes
The thermostat can operate in several switching modes:
- AUTO: Automatic switching based on programmed schedules.
- RANDOM: Random switching within a set interval.
- HOLIDAY: A vacation mode to keep the timer inactive for a specified period.
- MANUAL: Direct manual control of the output channels.
Settings Options
Additional settings include language selection, operating hours for individual channels, and time correction. Time correction allows for fine-tuning the real-time clock's accuracy, with a factory setting that can be adjusted by the user. Upon a device RESET, the time correction returns to its factory settings.
Deleting Programs and Resetting
Deleting All Programs
All set programs can be deleted by simultaneously pressing the 'PRG' and 'OK' buttons in the starting menu. The display will prompt for confirmation to complete the deletion.
Resetting the Device
The device can be reset by pressing the hidden 'RESET' button with a blunt-pointed object. A reset will restore the device to its default settings, including language (EN), zeroed data, and factory default program options.
Battery Replacement
The backup battery (CR2032) can be replaced without disassembling the device. It is crucial to disconnect the device from the power supply before replacing the battery. After replacement, the date and time must be reset.
Example of 326820 Programming
An example demonstrates programming the thermostat for two dependent thermostats with specific temperature and hysteresis settings. It also shows how to set an automatic temperature change at a future date and time.
Warning
The device is designed for connection to a 1-phase main alternating current voltage (AC 230V or 24V AC/DC) and must be installed according to applicable norms. Installation, connection, setting, and servicing should only be performed by qualified electrician staff who have familiarized themselves with these instructions. The device includes protection against overvoltage peaks, but higher-degree protection (A, B, C) should be installed upstream. Ensure proper air circulation for optimal operation, especially in high ambient temperatures. Use a screwdriver of approximately 2 mm for installation and setting. The device is fully electronic. Proper transportation, storing, and handling are essential for non-problematic function. If any signs of damage or malfunction are observed, do not install the device and contact the seller. The device can be recycled or stored in a protective dump after its lifetime.
