Why the air dries out during the heating season
Air that is too dry in your home in winter is above all a consequence of heating. Cold air can only hold little water vapour.
When it is warmed up in the room, the amount of water stays the same. But the relative humidity drops noticeably.
A calculation example shows how strong the effect is: outdoor air at 0 degrees with 90 percent relative humidity has only about 30 percent relative humidity once warmed to 20 degrees.[1] Exactly this happens every day during the heating season.
Especially in winter, when the radiators are running, closed rooms usually do not reach the recommended 40 to 60 percent relative humidity.[2] If your hygrometer shows less than 30 percent, the air is very dry and can irritate the mucous membranes.[1]
How do you notice dry air? Often first thing in the morning: your nose and throat feel dry, or there is a crackle when you touch the door handle. Such signs indicate that the room air contains too little moisture. If you have persistent symptoms, talk to your doctor.
A humidifier brings the humidity back
A humidifier reliably raises the humidity during the heating season.[3] That is why, for persistently dry air, we recommend a humidifier rather than individual home remedies, because it works in a targeted way.
Containers filled with water placed on radiators can moisten the air somewhat, especially in the cold season.[4] But they only release as much water as evaporates at the time, and they cannot be adjusted.
And what about ventilating? You need ventilation for fresh air, but against dry heating air it hardly helps: the cold air you let in dries out itself as it warms up.
Our Beurer LB 300 Plus works with natural cold evaporation. The principle is simple. The evaporation filter soaks up water, the fan draws the dry room air across the moist filter, the water evaporates and the humidified air is distributed evenly throughout the room.
Our LB 300 Plus humidifies rooms up to 45 m² with a humidification output of up to 300 ml/h.
What makes the Beurer LB 300 Plus pleasant to use in everyday life is its intelligent automatic mode: it measures the current humidity and adjusts the output to the humidity level you want. With three humidification levels, you keep the humidity constant at 40 %, 50 % or 60 % - exactly the range you want to reach.
The Beurer LB 300 Plus was named Testsieger (test winner) by Stiftung Warentest: GUT (1.9), 8 humidifiers tested, test issue 10/2025.[5] The test is titled ‘Luftbefeuchter im Test: Nein zur Keimschleuder − ja zum Feuchtekick’.
Measuring humidity and setting the target range
Measuring the humidity is the first step before you humidify. A hygrometer helps you monitor the humidity indoors.[6] This way you use your humidifier in a targeted way - and avoid excessively high values at the same time.
The Beurer HM 22 shows you the temperature, relative humidity, date and time on an easy-to-read 8.2 x 7.2 cm display. You can stand our thermo-hygrometer on its fold-out table stand or hang it on the wall.
After switching it on, the HM 22 can take 10 minutes until the temperature and humidity are displayed correctly. How accurately different devices measure is covered in our hygrometer test guide.
In its test “Hygrometer-Test: Auf diese Modelle können Sie sich verlassen” (24.03.2026), the verdict of stern Kaufkosmos on the Beurer HM 22 reads (translated from German): “Narrowly beaten, but also reliable and recommendable without reservation is the Beurer HM 22, which has a timer on board as a small extra (for example for the kitchen).”[7]
A simple rule applies to the target range: if the reading is below 40 percent, switch on the humidifier and select the appropriate level. With the Beurer LB 300 Plus, you set 40 %, 50 % or 60 %. The automatic mode maintains the value, and our HM 22 in the same room confirms it.
| Reading on the hygrometer | What it means | What you do |
|---|---|---|
| below 30 percent | very dry, can irritate the mucous membranes | switch on the humidifier |
| 30 to below 40 percent | too dry | set the humidifier to 40 % or 50 % |
| 40 to 60 percent | ideal range | maintain the value and check it regularly |
| permanently above 65 percent | mould can be encouraged | reduce humidification and ventilate |
Setting up, filling and maintaining in everyday life
The right placement plays a part in how evenly a humidifier humidifies the room air. Place the Beurer LB 300 Plus on a level, firm surface. Leave 30 cm of clearance around the device on all sides.
Do not operate the LB 300 Plus in rooms with high humidity or temperature fluctuations, such as bathrooms or kitchens.
Our LB 300 Plus has a 3.0-litre water tank. For the bedroom there is a night mode with whisper-quiet operation and a switched-off control panel, plus a timer from 1 to 9 hours. This way the humidifier runs at night without disturbing you.
With every humidifier, hygiene is a matter of care. We make it easy for you. On the LB 300 Plus, the filter drying function dries the filter after use to reduce bacterial growth.
Descale the filter and water tank weekly and replace the filter after 6 months at the latest. Do not leave water standing in the tank when the humidifier is not running. Read the instructions for use before first use.
Avoiding air that is too humid: the upper limit
Is more moisture automatically better? No, because air that is too humid creates new problems. Relative humidity above 65 percent can promote mould growth.[2]
In homes with little or no insulation, a stricter rule of thumb applies in winter: as a rule, the humidity there should stay below 50 percent.[8]In a poorly insulated home, you should therefore opt for the 40 % setting on the Beurer LB 300 Plus.
Also pay attention to the immediate surroundings of the device.
If carpets, curtains or the area around the humidifier become damp, reduce the humidification output of the LB 300 Plus. Our HM 22 helps you keep an eye on the upper limit.
Ventilating, home remedies or a humidifier: your decision
The decision depends on how long and how severely your air is too dry. If the hygrometer only shows values just under 40 percent on individual days, it is often enough to keep an eye on the readings.
If the humidity stays below 40 percent for weeks during the heating season, a humidifier is the reliable solution.
| Measure | What it does | When it fits |
|---|---|---|
| Ventilating | fresh air, but cold outdoor air becomes dry when heated | always, for air exchange |
| Bowls of water on the radiator | somewhat more moisture, not adjustable | as a small addition |
| Humidifier with automatic mode | maintains a set target value | when air is persistently dry |
| Thermo-hygrometer | shows whether the target range has been reached | in every case |
For living spaces up to 45 m², the pair of Beurer LB 300 Plus and Beurer HM 22 is a well-thought-out combination: the humidifier maintains 40 %, 50 % or 60 %, and the thermo-hygrometer confirms the value. You can find all our models under humidifiers from Beurer.
Take a look at our humidifiers if your air stays too dry during the heating season.
Frequently asked questions
What helps against dry air in the home?
A humidifier reliably helps against dry indoor air by bringing the relative humidity to 40 to 60 percent. The Beurer LB 300 Plus maintains a constant 40, 50 or 60 percent via its automatic mode. A thermo-hygrometer such as the Beurer HM 22 confirms whether the value has been reached.
Are humidifiers really useful?
Humidifiers make sense when the humidity stays below 40 percent during the heating season. That is when a device like the Beurer LB 300 Plus brings the room air back into the 40 to 60 percent range. Measure first with a hygrometer so that you humidify in a targeted way and not too heavily.
What are the disadvantages of humidifiers?
A humidifier needs regular care and an eye on the humidity. With the Beurer LB 300 Plus, you descale the filter and water tank weekly and replace the filter after 6 months at the latest. The filter drying function and the automatic mode take some of this work off your hands.
Is 70% humidity really that bad in the home?
A constant 70 percent humidity is too much for a flat, because above 65 percent mould can be promoted. If the level stays high, ventilate more often and do not humidify additionally; with the Beurer HM 22 you keep track of the trend.
