Product information Karl big

Despite his low power consumption, when humidifier Karl big gets going, he can humidify rooms of up to 150 m2 in no time at all. Whether it is a large office or a spacious bedroom or lounge, the evaporator can provide any big space with healthy and pleasant humidity. His elegant design looks fresh and light and fits wonderfully into any living environment. for undisturbed sleep, humidifier Karl big’s LED function lights can be dimmed or switched off altogether.

Important purchasing advice

We recommend a more powerful humidifier for Minergie houses (low energy or passive houses) or apartments for which calculations should be based on twice the room size. 

The reason for this lies in the continuous exchange of air: cold and dry outdoor air is heated up and channelled indoors. The moisture produced by people, animals, furniture, plants, cooking, showering, etc. is quickly directed outside by the continuous exchange of air, usually resulting in extremely dry air indoors. Controlled ventilation systems therefore have the same effect as open windows.

Product family Humidifier
System Evaporator
Color black
Accessories (included) 1 Water Cube, 4 humidifier filters
Room size m² 150
Room size m³ 375
Capacity 1100 g/h
Power level 4
Power consumption 2.4 – 40 W
Water tank capacity 10 l
Noise level 27 – 60 dB(A)
Weight 4.6 kg
Dimensions 502 x 335 x 242 mm


Video tutorials

Intelligent functions

Karl big is equipped with an integrated hygrostat and an auto mode. This means that the air is only humidified when really necessary and precisely to the desired humidity.

Easy handling

The 10-liter water container can be easily filled through a flap opening on the top, even during operation. When the water container is empty, Karl big switches off automatically.

Simple operation

Karl big offers Wi-Fi connection. This ensures that all functions can be controlled via the Stadler Form smartphone app and that the humidity can be monitored from anywhere at any time.


for rooms up to 50 m2


for rooms up to 100 m2

Karl big

for rooms up to 150 m2

Good to know

Find important information here

Set the output to the highest level.  
For the room size to be right, not only the room height (standard 2.5 m) but also whether or not the doors to the room are closed is a determining factor. If the doors to the room are left open, the adjacent rooms will also be included in the total area. If the relative humidity is low (below 35%), the humidity will not increase immediately. That is because the floors, furniture and walls absorb the moisture first before it ends up in the air. It can take up to two weeks for everything to absorb sufficient moisture for the humidity to start rising. As long as you keep having to top up the water regularly, your Karl big is working properly. 
If the humidifier filters are more than 2 months old or the upper part is hard and no longer saturated with water, the filters should be replaced.

For the hygienic and optimal use of the humidifier, the humidifier filter should be replaced at least every two months. If you continue to use the humidifier filter for longer than this, on the one hand the humidification output may deteriorate significantly and on the other, the antibacterial action of the filter can no longer be guaranteed. You can generally purchase humidifier filters from the place where you bought your device. The filter change indicator has to be reset manually after changing the filters.

Discolouration which is slightly yellowish or brownish is normal. Discolouration is caused by the substances in the mains water or the air. The poorer the water quality, the quicker the humidifier filter will become discoloured. Although this does not look pleasant, it is harmless as long as it is not due to mould. The discolouration will not affect the performance of your humidifier either. If you have not been using the humidifier filter for very long, you can rinse it thoroughly, turn it over and reuse it. If the humidifier filter is more than 2 months old, we recommend that you replace it.

It is also possible for the top part of the humidifier filters to become hard. During the evaporation process, the lime present in the water is collected in the humidifier filter as limescale. The harder the water, the quicker the humidifier filter will become hard. If you use water from a water softener which operates based on the principle of ion exchange, salt may collect in the humidifier filter rather than limescale. If you have been using the humidifier filter for less than 2 months, you can rinse it thoroughly with water, turn it over and put it back again. It is possible that you may notice an odour after you have turned over the humidifier filter depending on how contaminated the filter is by constituents in the air or the water.

If your Karl big or the humidifier filters smell unpleasant, there may be various reasons for this: water and air quality, a worn-out filter or even the fact that you have not used your Karl big for a long time and he has still water in his tank. In any case, we recommend that you clean and descale the device thoroughly. If you have been using the filter for less than 2 months, you can rinse it thoroughly with cold, clean water, turn it over and continue to use it.  

It may be that your external hygrometer and Karl big are measuring different values because the devices have been positioned in different places (heights) in the room. Different humidity values will be measured depending on the air flow and temperature in each case. A tolerance of +/- 5 % is normal depending on the type of device. Karl big measures the humidity levels best if he is positioned in the middle of the room so that the room air can flow towards the sensor as freely as possible. If that is not possible, we recommend positioning Karl big against the wall, with a clearance of at least 30 cm. Under no circumstances should Karl big be “hidden” in a corner of the room or behind a sofa/piece of furniture because this can have a negative effect on humidity measurement as well as humidification efficiency.

If your Karl / Karl big is leaking, this is usually due to water getting between the inner water basin and the outer shell during filling. In this case, we recommend removing the textile cover, emptying the water, removing the filters, and allowing the unit to dry upside down. Once Karl / Karl big is completely dry, you can replace the filters and put the textile cover back on.
Ideally, you fill it using the top filling flap. Of course, you can also fill the humidifier at the tap, but you must be very careful not to spill any water during transport.

Karl big



sehr zufrieden mit Karl big

Karl big steht seit einigen Wochen bei mir im Wohnzimmer und bin begeistert :-) Durch die App kann ich Karl big so einstellen, dass er während meiner Abwesenheit meist auf den hohen Stufen läuft diese sind mir - wenn ich zu Hause bin - definitiv z...

Review from Anonymous at 08.02.2023

Karl big ein starker Kerl

Top Beratung, schnelle Lieferung, einfache, logische Bedienung. Karl big ein starker Kerl sorg rundum für optimales Raumklima.

Review from Anonymous at 23.12.2022
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Karl big

The Designer

Since the very start, I have had the privilege to co-develop and design products for Martin Stadler and the Stadler Form Team. What began with Fred, has grown into an attractive, small but fine range of products. This experience, and being part of the team, has greatly enriched myself and my work as a designer ...

Matti Walker

Learn more

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