
Karcher Air Purifier AF 20


General notes
Read these original instructions and the safety instructions chapter before using the device for the first time. Act in accordance with them. Keep these original instructions for future reference or for future owners.
Safety instructions
Hazard levels
DANGER
- Indication of an imminent threat of danger that will lead to severe injuries or even death.
WARNING
- Indication of a potentially dangerous situation that may lead to severe injuries or even death.
CAUTION
- Indication of a potentially dangerous situation that may lead to minor injuries.
ATTENTION
- Indication of a potentially dangerous situation that may lead to damage to property.
General safety instructions
DANGER
- Only connect the device to alternating current. The voltage indicated on the type plate must match the voltage of the power source.
- Never touch the mains plug and socket with wet hands.
- Risk of asphyxiation. Keep packaging film out of the reach of children.
- Operation in explosive atmospheres is prohibited.
WARNING
- Persons with reduced physical, sensory or mental capabilities, or those with a lack of experience and knowledge, are only allowed to use the appliance if they are supervised or have been instructed with respect to using the appliance safely, and understand the resultant dangers involved.
- Children from the age of 8 may use the appliance if they are supervised or have been instructed in its use by a person responsible for their safety, and if they have understood the resultant dangers involved.
- Children must not play with the appliance.
- Children must be supervised to prevent them from playing with the appliance.
- Children may only perform cleaning work and user maintenance under supervision.
- Check the power supply cable with the mains plug for damage before each use. Do not put the device into operation with a damaged power supply cable. Have a damaged power supply cable replaced immediately by the authorised customer service / qualified electrician.
- Switch off the device immediately and remove the mains plug before performing any care and service work.
CAUTION
- Do not pull the mains plug out the socket using the power supply cable.
- Have repair work, installation of spare parts, and work on electrical components carried out by the authorised customer service only.
- It is prohibited to cover the air inlet and outlet.
- Switch off the device after each use and remove the mains plug.
- Do not place the device near a heat source.
- The device is not a replacement for appropriate ventilation.
- The device must be placed on an even, firm subsurface.
- Only use accessories and spare parts that are approved by the manufacturer. Only original accessories and original spare parts ensure that the appliance will run fault-free and safely.
- Do not use the device in damp conditions or in rooms with high ambient temperatures, e.g., the bathroom.
Intended use
In accordance with the descriptions and safety instructions listed in these operating instructions, use the device only as an air purifier.
- The device is intended for use as an air purifier.
- The device is suitable for both private and commercial use.
- The device is intended only for indoor use.
Environmental protection
The packing materials can be recycled. Please dispose of packaging in accordance with the environmental regulations.
Electrical and electronic devices contain valuable, recyclable materials and often components such as batteries, rechargeable batteries or oil, which – if handled or disposed of incorrectly – can pose a potential danger to human health and the environment. However, these components are required for the correct operation of the device. Devices marked by this symbol are not allowed to be disposed of together with the household rubbish. Notes on the content materials (REACH) Current information on content materials can be found at: www.kaercher.de/REACH
Accessories and spare parts
Only use original accessories and original spare parts. They ensure that the appliance will run fault-free and safely. Information on accessories and spare parts can be found at www.kaercher.com.
Scope of delivery
The scope of delivery for the appliance is shown on the packaging. Check the contents for completeness when unpacking. If any accessories are missing or in the event of any shipping damage, please notify your dealer.
Warranty
The warranty conditions issued by our sales company apply in all countries. We shall remedy possible malfunctions on your device within the warranty period free of cost, provided that a material or manufacturing defect is the cause. In a warranty case, please contact your dealer (with the purchase receipt) or the next authorised customer service site. (See overleaf for the address)
Description of the device
For the illustrations, refer to the graphics page. Illustration A
- Operation button for Device On / Off
- Operation button for Function lock
- Display PM 2.5 Air Quality Index
- The operation button for switching off the display
- Display for fan level
- Operation button for Auto mode On / Off
- Fan level operation button
- Operation button for Sleep mode On / Off
- Timer display
- Operation button for Timer
- Filter service life display
- Operation button for Filter reset
- Air quality display and device display
- Filter cover lock
- Filter cover
- Filter tab
- filter
- Connection for the power supply unit
- Device sensor
- Power adapter
Note: The function settings are only possible via the operation buttons and not via the displays.
Inserting the filter
Before the initial start-up, the fine filters already installed in the unit must be unpacked.
- Turn the device over, and turn the filter cover lock 45 degrees clockwise.
Illustration B - Remove the filter cover.
Illustration C - Remove the packed filters.
Illustration D - Unpack the filters.
Illustration E - Insert the unpacked filters. Ensure that the draw shackles are visible and point inwards.
Illustration F - Put on the filter cover and turn the lock 45 degrees anticlockwise. Turn the device over with the display facing upwards.
Illustration G - Place the device on a level surface. Ensure that a distance of 30 cm is maintained to each side.
Illustration H
Note- Do not place the device on hot surfaces or in the immediate vicinity of the room heating.
- Do not allow any liquids or foreign bodies (e.g. metallic objects) to enter the device.
- Insert the plug of the power supply unit into the device and insert the mains plug into the socket.
Illustration I
The device is ready for operation.
Note: The first time you use the device, we recommend allowing it to run overnight to perform an initial basic cleaning of your room.
Note: The table with the hours of the display symbols for the filter service life, see Replacing the filter
Operation
Switching the device on/off
- To switch on the device: Press the on/off button on the device.
Illustration I
The device starts automatically.
Note: After the system is switched on, the displays and buttons on the control panel light up briefly. The integrated air quality sensor measures the air quality in the room automatically. - If required, the following functions, for example, can be set via the operation buttons:
- Fan level
- Auto mode
- Sleep mode
- Timer
- To switch off the device: Press the On/Off switch of the device.
The displays and buttons on the control panel go out. The device is switched off.
Setting auto mode
In automatic mode, the air purifier sets the appropriate fan level depending on the air quality. In the event of poor air quality, for example, the fan level is automatically set high.
Symbol for the auto mode operation button:
- Press the auto mode operation button. The automatic mode is switched on or off.
Setting sleep mode
In sleep mode, the fan runs at the lowest speed and is therefore very quiet. All light symbols are off.
- Press the sleep mode operation button. The sleep mode is switched on or off.
Symbol for the sleep mode operation button:
Setting the fan level
Depending on the air quality, the fan level can be manually set to level I, II or III. If the air quality is poor, for example, to filter out smoke, the blower should run at maximum speed (level III) for 15 – 20 minutes.
Note: To clean the air effectively, keep windows and doors closed while the air purifier is switched on.
Symbol for the fan level operation button:

- Press the fan level operation button repeatedly until the desired level is reached.
The selected fan level is displayed on the control panel.
Setting the timer
The timer can be set to 2, 4, 6 or 8 h run time. When the set time has elapsed, the device switches off automatically. The fan level can be changed at any time.
Symbol for the timer operation button:
Switching on: Press the Timer operation button repeatedly until the desired run time is reached. The display lights up. The set run time is displayed in the control panel.- Switching off: Press the Timer operation button until the timer display goes out. Timer is off.
Lock /unlock the control panel
To prevent accidental change of settings, e.g. by children or pets, the control panel can be locked.
Symbol for the lock operation button and display for control panel:
- Lock: Press the button for 3 seconds.
- Unlock: Press the lock button for 3 seconds.
Display PM 2.5 air quality
The display shows the concentration of fine dust (PM 2.5) numerically in the unit μg/m³. In addition, a colour index provides information about the air quality:
Transport and storage
CAUTION
- Failure to observe the weight
- Risk of injury and damage
- Be aware of the weight of the device during transport and storage.
- Store the device only in dry indoor rooms.
Care and service
Cleaning
DANGER
- Danger of death from electric shock
- Liquids can conduct electricity and thus cause serious or fatal injuries.
- Always disconnect the power supply unit from the socket before cleaning and maintenance work.
- Never immerse the device or the power supply unit in water.
- Never use wet cloths to clean the device or the power supply unit.
- Switch off the device.
- Unplug the power supply unit from the socket.
- Wipe the device with a soft, dry cloth. Do not use abrasive or corrosive detergents.
Replacing the filter
The filter should be changed after 2500 – 3000 hours of operation at the latest. If the device becomes louder, an unpleasant smell emanates from the device (filter) or the filter is visibly dirty, it should be changed at an earlier stage. The symbol flashes in the display to remind you of a required filter change.
Symbol for the operation button for filter reset:

Depending on the service life, the following number of symbols is displayed:
Switch off the device, and disconnect the power supply unit from the socket and device.
Illustration J- Turn the device over, and turn the filter cover lock 45 degrees clockwise.
Illustration B - Remove the filter cover.
Illustration C - Remove the filters.
Illustration D - Unpack the new filters.
Illustration E - Insert the unpacked filters. Ensure that the draw shackles are visible and point inwards.
Illustration F - Put on the filter cover and turn the lock 45 degrees anticlockwise. Turn the device over with the display facing upwards.
Illustration G - Connect the power supply unit to the device and the socket.
- Switch the device on.
- To reset the filter (Reset), press the symbol
for 3 seconds.
Illustration K
- To reset the filter (Reset), press the symbol
Troubleshooting guide
Malfunctions often have simple causes that you can remedy yourself using the following overview. When in doubt, or in the case of malfunctions not mentioned here, please contact your authorised Customer Service.


Technical data

* At 3 m ceiling height and 3 x air exchange per hour Subject to technical changes without notice.
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Karcher Air Purifier AF 20-FAQs
What is the Karcher AF 20 air purifier?
The AF 20 is a compact air purifier designed for small rooms up to 40 m² (430 sq. ft.). It delivers an air throughput of up to 220 m³/h and features a space-saving vertical design.
Is Karcher a German brand?
Yes, Kärcher is a globally recognized cleaning technology company from Germany, operating in more than 190 countries.
Is the AF 20 suitable for bedrooms?
Yes. It is ideal for bedrooms and small living areas. Running it at night can help improve air quality and support better sleep.
Does the AF 20 remove dust and allergens?
Yes. With its H13 HEPA filtration system, it effectively captures dust, pollen, fine particles, and other airborne allergens.
Can it remove odors and smells?
Yes. The integrated activated carbon filter helps reduce unpleasant odors, smoke, and certain gases.
How long should I run the air purifier daily?
For best results, you can run it continuously or use the automatic mode to maintain clean indoor air throughout the day.
Does the Karcher AF 20 consume a lot of electricity?
No. Like most room air purifiers, it uses moderate electricity and is energy-efficient for continuous use.
How often should the AF 20 filter be replaced?
Filter life depends on usage and air quality, but generally it should be checked regularly and replaced when indicated for optimal performance.
Can I wash and reuse the filter?
HEPA filters are typically not washable. Cleaning may damage the filter structure. Always follow the manufacturer’s maintenance guidelines.
Where should I place the air purifier?
Place it in an open area with good airflow. Avoid positioning it directly against walls, behind furniture, or near vents.


Switching on: Press the Timer operation button repeatedly until the desired run time is reached. The display lights up. The set run time is displayed in the control panel.
Switch off the device, and disconnect the power supply unit from the socket and device.