Zehnder/Acova IHD Immersion Heater
Model: Immersion Heater Design (IHD)
This document provides comprehensive operating instructions and technical information for the Zehnder/Acova IHD immersion heater, a modern design solution for bathroom radiators. It covers installation, usage, features, troubleshooting, connectivity options (Easy Control Unit, Zehnder Connect app, Connect-Box), and technical specifications.
Introduction
Thank you for choosing the Zehnder/Acova IHD immersion heater. The IHD is either integrated into your chosen bathroom radiator or available as a separate accessory to equip your existing bathroom radiator. The IHD was developed with a wide range of applications in mind, designed to be the perfect aesthetic solution for your radiator, available in matching colours and compact dimensions. It meets various needs, such as surface temperature adaptation, and is easy and comfortable to use.
The optional Easy Control Unit (RCE) allows for IHD operation. If the IHD is ordered as an accessory for a mixed-use kit, the control unit must be ordered separately. Alternatively, control is possible via smartphone using the Zehnder Connect application.
For ease of use, a quick start guide is included. This document provides detailed information on all product aspects for optimal use. If the immersion heater is purchased separately from the bathroom radiator, installation on a compatible radiator must be performed by an authorized and qualified technician. Please check the package contents upon unpacking.
Index
The document is structured into the following sections:
- 1. Functions of the Appliance
- 2. Usage (Commissioning, LED Status Indicator, Confirmation, Reset, Troubleshooting)
- 3. IHD with Easy Control Unit (Functions, Commissioning, Coupling, Mode Selection, Standby, Temperature, Boost, Reset, Other Displays, Troubleshooting)
- 4. IHD with Connect App (Functions, Commissioning, Coupling, Time Program, Surface Temp Limitation, LED Brightness, Adaptive Heating, Energy Consumption, Troubleshooting)
- 5. IHD with Connect-Box (Functions, Commissioning, Coupling, Troubleshooting)
- 6. Connecting Multiple IHD Units
- 7. Technical Information
- 8. Disclaimer, Service, Warranty, Delivery Content, Disposal
1. Functions of the Appliance
The IHD features a push button for coupling, activating the LED, and status display. It also includes an LED status indicator for connection status, heating status, and errors, along with a temperature sensor.
Diagram: IHD Components illustrates the push button, LED status indicator (showing connection status, heating status, error), and temperature sensor.
Note on LED Brightness: The LED indicator reduces its brightness after ten seconds of inactivity. Brightness can be adjusted via the Zehnder Connect app. Pressing the button restores full brightness.
2. Usage
2.1 Commissioning
After electrical connection, the IHD enters an initialization phase, indicated by the status LED lighting up white for four seconds. For initial setup, the IHD must be paired with the Easy Control Unit (see Section 3.3). During pairing, the LED lights up violet.
2.2 LED Status Indicator
The LED status indicator provides information on the IHD's operational state:
| Illustration | Colour | Description |
|---|---|---|
| Violet | Device not yet paired. Starts coupling process (see 3.3). | |
| Violet flashing | Coupling in progress. | |
| Green | Radiator is heating. Desired ambient temperature not yet reached. | |
| White | Radiator is not heating. Desired ambient temperature reached. | |
| Violet + red flashing | Connection lost (see 5.5). | |
| Red | Error (see 2.5). |
Confirmation of Change: When settings are modified (via Easy Control Unit or app), the IHD flashes green or white twice to confirm the settings have been applied.
2.4 Reset
To reset the IHD, press and hold the button for ten seconds until the status LED flashes white. The device will emit three audible signals and restart according to section 2.1. A reset returns all parameters to default values and disconnects the unit; re-pairing is required.
2.5 Troubleshooting
Problem: IHD not working (LED off)
Cause: IHD element not powered.
Repair: Ensure correct connection and power supply. Contact after-sales service if issues persist.
Problem: IHD indicates error (constant red LED)
Cause: Temperature sensor issue or hardware malfunction.
Repair: Reset the IHD (see 2.4). Contact customer service if the error recurs.
Problem: IHD in Standby or Frost-free mode
Repair: Switch to Eco, Comfort, or Boost mode.
Problem: Radiator not heating (white status LED)
Cause: Setpoint temperature is lower than the current ambient temperature.
Repair: Increase the setpoint temperature.
Problem: Radiator not heating (white status LED)
Cause: Maximum surface temperature setting is too low, limiting performance.
Repair: Increase the maximum surface temperature via the Connect app (see 4.5).
Problem: Setpoint temperature not reached
Cause: Maximum surface temperature setting is too low.
Repair: Increase the maximum surface temperature via the Connect app (see 4.5).
Problem: Setpoint temperature not reached
Cause: Room heat load exceeds radiator output.
Repair: Consider additional heating options for the room.
Problem: Setpoint temperature not reached
Cause: Ambient temperature sensor is disturbed.
Repair: Avoid heat sources near the sensor. Use calibration in the Zehnder Connect app.
Power Failure: After a power outage, the IHD restarts with the last selected heating mode and setpoint. If Boost mode was active before the outage, it restarts in the mode that was active prior to Boost.
If problems persist, reset the device and recheck steps. If unresolved, contact customer service.
3. IHD with Easy Control Unit
If products (control unit, app) have already been paired, the IHD must first be reset (see 2.4).
3.1 Functions of the Easy Control Unit
The Easy Control Unit (RCE) features controls for heating modes (Standby, Frost-free, Eco, Comfort, Boost), a screen displaying set temperature and boost duration, and status indicators for mode, connection, and errors. It also includes buttons for mode selection, increasing (+), and decreasing (-) values.
Diagram: Easy Control Unit (RCE) shows the buttons (Standby, Mode, Plus, Minus) and display elements (Screen showing set temperature, boost duration, error status; Status indicators for Time Program (AUTO), low battery warning, connection status, temperature override).
Note on Screen Timeout: The screen turns off after ten seconds of inactivity. The next button press will reactivate the screen, displaying the active heating mode without changing settings.
3.2 Commissioning: Remove the battery protection strip to activate the control unit. During initialization, all LEDs light up for two seconds. The first power-on automatically starts the pairing process.
Battery Replacement
To replace batteries, open the battery compartment and insert two new AA 1.5V batteries, observing polarity. Rechargeable batteries are not recommended.
3.3 Coupling Easy Control Unit and IHD
To connect the Easy Control Unit (RCE) to the IHD, initiate the coupling process on the IHD by pressing the button twice until the status LED flashes violet. The coupling process remains active for 60 seconds. During this time, press any button on the RCE. Successful coupling is confirmed by "ok" on the RCE, and the IHD status LED turns white or green (depending on heating status).
3.4 Mode Selection
Cycle through heating modes (Comfort, Boost, Frost-free, Eco) by pressing the Mode button.
3.5 Standby Mode
Hold the Standby button on the RCE for two seconds to put the RCE and connected IHD into Standby mode. In Standby, all heating functions are deactivated. This is confirmed by two audible signals from the IHD. Exiting Standby is confirmed by one audible signal. Buttons on the RCE have no effect in Standby mode, except to wake the screen.
3.6 Ambient Temperature Selection
The desired ambient temperature for Comfort and Eco modes can be set in 0.5°C increments using the Plus or Minus buttons. Note: The ambient temperature in Eco mode cannot be higher than the Comfort mode temperature minus 1°C. The selectable ambient temperature range is: Comfort: 7-28°C (default 21°C), Eco: 7-19°C (default 16°C), Frost-free: 7°C (fixed).
3.7 Boost Mode
Boost mode can be activated via a quick access function: briefly press any button to wake the screen, then hold the Plus button for two seconds. The desired duration can be set using the Plus or Minus buttons, in 5-minute increments (0-95 minutes) or 1-hour increments (2-4 hours). The default duration is 60 minutes.
3.8 Reset
To reset the Easy Control Unit, simultaneously press and hold the Mode and Standby buttons for five seconds until "rES" flashes on the screen. The RCE will then restart as described in section 3.2. After a reset, all settings revert to default values, and the connection to the IHD is removed; re-pairing is required.
3.9 Other Displays
Open Window Detection: If the IHD is in Eco or Comfort mode and detects a rapid temperature drop (e.g., from an open window/door), it automatically switches to Frost-free mode to save energy. This is indicated on the RCE by a flashing frost-free symbol. If the window/door is closed, the system automatically returns to the last selected heating mode. Manual deactivation of active open window detection is possible by pressing the Mode button on the RCE or the button on the IHD.
3.10 Easy Control Unit (RCE) and Connect App
The Connect app can be used with the Easy Control Unit for advanced settings and weekly programming. First, pair the IHD with the RCE. Then, use the app as described in section 4.3.
Time Program: Once the IHD and RCE are connected to the app, the system enters programmed mode, automatically switching between Eco and Comfort modes based on a pre-set weekly schedule. The Time Program is indicated on the RCE by the "AUTO" symbol. This feature can only be activated/deactivated within the Connect app.
Note on Pilot Wire: If the IHD is controlled by a pilot wire (French market only), the RCE displays the current mode with a flashing symbol. Mode changes via RCE are only possible for modes lower than the pilot wire mode (e.g., Eco to Frost-free or Standby, but not Eco to Comfort).
3.11 Troubleshooting
Error Messages:
| Error Message | Cause | Repair |
|---|---|---|
| E1 | Connection to IHD interrupted. | Ensure IHD is powered on. Check distance between control unit and radiator; move RCE closer to IHD. Reset RCE and re-pair if error persists. |
| E5, E6 | Detected hardware malfunction. | Reset RCE or briefly remove batteries. Contact after-sales service if error recurs. |
Other Problems:
| Problem | Cause | Repair |
|---|---|---|
| RCE unresponsive (screen off) | No batteries inserted or low battery level. | Insert two new AA 1.5V batteries (avoid rechargeable). |
| RCE unresponsive (screen off) | Batteries inserted incorrectly (polarity). | Insert batteries correctly, observing polarity. |
| Low battery warning symbol illuminates. | Low battery level. | Insert two new AA 1.5V batteries (avoid rechargeable). |
| RCE display flashes rapidly. | Batteries inserted incorrectly (polarity). | Insert batteries correctly, observing polarity. |
| RCE displays "nok". | Coupling with IHD failed. | Ensure IHD is powered on. Check distance between control unit and radiator; move RCE closer to IHD and repeat coupling. Reset RCE/IHD and re-pair if error persists. |
| Eco mode ambient temperature cannot be adjusted. | Linked temperatures setting is active. Eco temperature is set to Comfort temperature -3.5°C. | Check settings in the Connect app and disable linked temperatures. |
3.12 RCE Technical Information
Device Name: Easy Control Unit (Remote Control Easy)
Operating Voltage Range: 2-3V
Radio Frequency: 868.2 MHz
Operating Temperature Range: 0°C - 40°C
Dimensions (L x W x H): 4.7 cm x 13 cm x 1.8 cm
Weight: 116 g
Certification: CE
Technical Specifications Summary: Includes nominal voltage, power ratings (e.g., 300W), IP protection, max service pressure, various lengths, protection class, Bluetooth/Comfo-RF frequencies, and certification marks.
4. IHD with Connect App
The IHD can also be controlled via Bluetooth using the Zehnder/Acova Connect app, available on the Play Store (Android) and App Store (iOS). If products are already paired, reset the IHD first (see 2.4).
4.1 App Functions
The Connect app offers advanced features including:
- Weekly program creation for automated ambient temperature regulation.
- Setting maximum surface temperature for heating regulation.
- Recording energy consumption history.
- Adjusting LED status indicator brightness.
- Adaptive heating control settings and information.
- Setting boost duration.
- Activating/deactivating open window detection.
- Activating/deactivating linked temperatures.
- Sensor calibration for precise ambient temperature regulation.
- Absence planner.
- IHD software updates.
4.2 Commissioning: Download and install the Zehnder/Acova Connect app. Minimum requirements: Android 6.0+ or iOS 13.0+, Bluetooth 4.0+. Grant necessary permissions during first use.
4.3 Coupling App and IHD
To connect via Bluetooth, initiate pairing in the Connect app. Search for available devices, select your IHD, enter a username (optional), and tap "Connect". Press the IHD button within 30 seconds when its LED flashes violet to confirm pairing. The status LED will turn white or green upon successful connection.
4.4 Time Program
Once connected to the app, the IHD enters programmed mode, automatically switching between Eco and Comfort modes based on a weekly schedule. This feature is activated/deactivated in the app under "Settings" → "Mode".
4.5 Surface Temperature Limitation
The maximum surface temperature is defaulted to 80°C but can be adjusted in the app. A lower setting is recommended for chrome radiators for safety, though it may affect heating performance.
4.6 LED Status Indicator Brightness
The brightness of the LED status indicator can be adjusted in the app. At 0% brightness, the LED turns off after ten seconds of inactivity. Pressing the IHD button restores maximum brightness.
4.7 Adaptive Heating Control
In programmed mode, adaptive heating determines the time needed to reach the target temperature when switching from Eco to Comfort, initiating heating earlier. This feature is enabled by default and can be deactivated in the app. It is only available in programmed mode.
4.8 Energy Consumption Information
After initial connection to the app, the IHD continuously measures energy consumption. Historical data (daily, monthly, annual) is available in the app. Resetting the IHD erases this data. Time program and energy monitoring require current time/date information; re-open the app after a power outage.
4.9 Troubleshooting
Problem: App not finding Connect-Box
Cause: Connect-Box not configured correctly.
Repair: Ensure Connect-Box and app are on the same network.
Problem: IHD not found/added to app
Cause: No connection to IHD.
Repair: Confirm coupling (violet LED, press button within 30s). Check distance; move smartphone closer to IHD and retry. Reset and re-pair if persists.
Problem: App/IHD link interrupted
Cause: Distance between smartphone and IHD too great.
Repair: Move smartphone closer to IHD and retry.
Problem: IHD LED flashes violet again
Cause: Coupling with app failed.
Repair: Confirm coupling (violet LED, press button within 30s). Check distance; move smartphone closer to IHD and retry.
Problem: IHD LED flashes red/violet
Cause: Connection to Connect-Box interrupted.
Repair: Ensure Connect-Box is powered on. Check distance; move Connect-Box closer to IHD and retry.
Problem: System not accessible remotely
Cause: Connect-Box not connected to Internet.
Repair: Ensure "Connect to Internet" is enabled in app settings.
5. IHD with Connect-Box
The IHD can be integrated into the Zehnder Smart Home system via the Zehnder Connect-Box, which acts as a central gateway for intelligent networking of multiple Zehnder products across different rooms. The Connect-Box is available separately.
If products are already paired, reset the IHD first (see 2.4).
5.1 Connect-Box Functions
The Connect-Box, in conjunction with the Connect app, offers advanced functions including centralized control of multiple devices and rooms, remote access via the internet, and Zehnder Cloud access.
5.2 Commissioning
Configure the Connect-Box according to its manual. Open the Connect app, search for devices, select your Connect-Box, enter a username, and tap "Connect". Confirm the coupling process by pressing the Connect-Box button. The IHD LED will flash violet, then turn white or green.
5.3 Coupling Connect-Box and IHD
The coupling process must be completed within 60 seconds. Once the IHD is coupled to the Connect-Box, it cannot be connected to the app via Bluetooth or directly to the Easy Control Unit. A reset is required to change connection settings. In the Connect app, navigate to "Settings" → "Rooms and devices", select a room, tap "Add devices", and follow the on-screen instructions and IHD prompts.
5.4 Coupling Connect-Box and Easy Control Unit
First, reset the Easy Control Unit (see 3.8). Then, couple the IHD to the Connect-Box (as per 5.3). Finally, add the RCE via "Add devices" in the app within the same room. Note: RCE overrides in Time Program mode are temporary (see 3.10).
RCE Mode Selection: If the IHD and RCE are connected to the Connect-Box, certain modes (Boost, Standby) can be selected on the RCE, applying to all devices in the same room. Other modes must be selected via the app.
5.5 Troubleshooting
Problem: App not finding Connect-Box
Cause: Connect-Box not configured correctly.
Repair: Ensure Connect-Box and app are on the same network.
Problem: IHD not added to Connect-Box
Cause: No connection to IHD.
Repair: Ensure IHD is powered on. Check distance between Connect-Box and IHD; move closer and retry. Reset devices and retry if persists.
Problem: IHD LED flashes violet again
Cause: Coupling with Connect-Box failed.
Repair: Ensure coupling process on IHD completes within 60 seconds. Retry "Add device" in the app.
Problem: IHD LED flashes red/violet
Cause: Connection to Connect-Box interrupted.
Repair: Ensure Connect-Box is powered on. Check distance; move Connect-Box closer to IHD and retry.
Problem: System not accessible remotely
Cause: Connect-Box not connected to Internet.
Repair: Enable "Connect to Internet" in app settings.
6. Connecting Multiple IHD Units
If you have multiple IHD units, they can be linked via an Easy Control Unit for synchronized settings (e.g., ambient temperature, Boost mode), useful for radiators in the same room. Reset is required if already paired.
Process: Couple one IHD to an Easy Control Unit (see 3.3). Press the IHD button twice until the status LED flashes violet. Then, briefly press the button on the other IHD. The status LEDs on both units will turn white or green. A Connect-Box is not required for linking two IHDs; additional units can be added by repeating the steps.
7. Technical Information
Nominal Voltage: 220-240 V~
Nominal Power: 200 W / 300 W / 400 W / 500 W / 600 W / 750 W / 900 W / 1000 W / 1200 W
Protection Index: IP54
Max. Service Pressure: 0.4 MPa (4 bar)
Control Unit Length (incl. heater): 355 mm to 875 mm (various models)
Visible Control Unit Length (after mounting): 55 mm
Protection Class: Class II
Cable Length: 1.20 m
Bluetooth Low Energy Frequency: 2.4 GHz
Comfo-RF Frequency: 868.2 MHz
Certification: CE
Labeling Information: Includes Zehnder and Acova brand marks, CE conformity, disposal instructions, hot surface warning, voltage, power, device name, manufacturer, and order number/date.
8. Disclaimer, Service, Warranty, Delivery Content, Disposal
Smart Home Integration: The IHD can integrate into the Zehnder Smart Home system via the Connect-Box for centralized control.
Disclaimer: Zehnder is not liable for damages resulting from misuse, unauthorized modifications, or dry running of the appliance. All work must be performed according to the manual by authorized personnel.
Customer Service: For technical inquiries, contact your reseller or local manufacturer representative.
Warranty: Refer to purchase documents for warranty conditions. Contact your reseller for warranty questions.
Delivery Content (without radiator): Includes IHD unit, Easy Control Unit (RCE) if ordered as accessory, quick start guides, and safety/mounting notice.
Disposal: Electrical and electronic equipment waste should not be disposed of with household waste. Recycle through appropriate collection centers.
