Moisturize or dehydrate, that is the question!

Humidity and temperature meter Bionaire BT-254C.
One of the popular Duracraft DH-837 E humidifiers distributes «cold steam» indoors with the help of a fan.
The Bionaire CM-1 humidifier works on the «hot steam» principle. It is for him that the Bionaire BT-254C moisture meter should be closely monitored.
The Airwasher humidifier periodically «asks» for a bottle of liquid «Bio-Absorber».
The principle of operation of the Swiss humidifier Defensor PH-5:
1. Water tank
2. Water level regulator
3. Pallet

4. Centrifuge
5. Porous activated carbon atomizer
6. Triple air filter
7. Fan.

Above and below: «Air washer» — humidifier-air-purifier Venta-Airwasher (Germany). Performance also depends on size.

At first, you are perplexed when you read how a well-known Swiss company in its advertising brochure offers to buy both a humidifier and a dehumidifier, while claiming that both devices will make the atmosphere of your home pleasant and healthy! Meanwhile, there is no contradiction: both excessive and insufficient humidity have a bad effect on well-being. How optimal humidity is achieved is described in our article.

Sanitary standards recommend maintaining indoor relative humidity of 45-55% at a temperature of 22-25C. Doctors say that at a humidity of less than 30%, the mucous membrane of the human respiratory system dries, and this leads to an increase in its susceptibility to respiratory infections. People with dry skin are most sensitive to low humidity. Wooden furniture, musical instruments, parquet boards also suffer from dry air. The lack of moisture in the air contributes to the accumulation of static electricity and prevents the settling of room dust.

Excessive humidity is also fraught with unpleasant consequences. Patients with hypertension and atherosclerosis do not tolerate a humid atmosphere. The increased content of water in the air leads to its condensation on cooled objects, in a cool place in the apartment and to the growth of bacteria and mold. This problem is not speculative — it already exists in Europe. As a result of the struggle to save heat in the construction of housing, double-glazed windows have become widespread, due to which air exchange with the street has decreased and, of course, heating costs, but indoor humidity has increased and mold has appeared.

Humidity

Absolute humidity — the amount of water (water vapor) in the air (measured in g / m³). However, the content of water vapor in the air has its own limit, above which water falls in the form of dew or pours in the form of rain.
Relative Humidity — the degree of saturation of the air with water. For example, if there is 17.3 g/m in the air³ water, then at a temperature of 30With humidity — 57%. When the temperature drops to 10With the air becomes supersaturated with water, and excess moisture will fall in the form of dew in the amount of 7.9 g / m³.
Dew point — the temperature at which precipitation begins, for example, in the form of water droplets on leaves. If there is a damp corner in the room and the cause of dampness is not an elementary leak, then the temperature in this corner is below the dew point.The main sources of moisture in the home, in addition to inclement weather, are the kitchen, bathroom and … the person himself. A family of three vaporizes and exhales approximately 300 g/h of moisture, which is the equivalent of one running household humidifier. But often this «free device» is not enough. Table 1 shows the maximum amount of water contained in the air depending on the temperature. It turns out that at a temperature of 20C in the air of a room with a volume of, for example, 60 m³ (area 20 m² and a ceiling height of 3 m) in the form of water vapor is up to 1 liter of water, which, when the temperature drops, can be deposited on the walls if special measures are not taken.

In our climate, problems associated with low relative humidity most often occur in the winter season. Already at -10C absolute air humidity does not exceed 2.14 g/m³so the fresh winter air is quite dry. When airing, the humid indoor air is replaced by dry outdoor air, and it becomes necessary to humidify it. The problem of dry winter air is most familiar to the inhabitants of modern cottages and residents of Stalinist houses. The former became victims of improperly arranged air exchange in their homes due to the design of the cottage, while the latter are forced to open the vents and windows wide open in winter due to the too intensive work of central heating radiators.

Another source of dry air was a household window air conditioner. The temperature of the air in the stream passing through the air conditioner may drop to the dew point, in which case the water vapor begins to condense in a special pan, and then discharged through the drain pipe to the street, while the room becomes dry. Until recently, housewives got out of the situation by placing jars of water along the water heating radiators in winter, and with wet towels in summer. Now air humidifiers have entered the fight for a healthy microclimate.

Maximum amount of water in the air

Humidifiers

According to the device, humidifiers are divided into three groups. A device that works on the principle of «hot steam» and is not much different from a kettle boiling on the stove, heats water and turns it into steam. Such a humidifier has a high performance (250-700 g/h) and consumes a lot of electricity (300-500 W). The kit sometimes includes nozzles for inhalation and a container for flavoring additives.

Many models, apparently, for the sake of simplifying the design, are not equipped with a fan and humidify the air exclusively around them, so it is not recommended to place them closer than 15 cm from the wall so that the wallpaper does not peel off. Humidifiers of this type must necessarily have an air humidity sensor and have the property of automatic on / off. Otherwise, the harm from waterlogging the premises will be the only result of their use. According to the principle of «hot steam» humidify the air, for example, Boneco 1345 and Bionaire CM-1.

More economical humidifiers (power consumption 20-50 W), based on the principle of «cold steam». With the help of a fan, they drive the air through wet filters and return it to the room humidified and purified, saturating it with water at a rate of 100-350 g/h. The performance of this type of appliance depends on the humidity in the room: the lower the humidity, the higher the evaporation rate at the same fan speed.

The brochures claim that the «cold vapor» humidifier also slightly cools the air. This, of course, is true, but only its cooling abilities (taking into account the heat generated by the fan motor) are hardly enough to compensate for the heating capabilities of a table lamp. This type of humidifier (it includes Duracraft DH-830 and Bionaire EN-2010) is considered the most successful in terms of price and quality.

The ability to cool the air when water evaporates is the basis for the operation of air coolers, which, according to the principle of operation, are no different from “cold steam” humidifiers, but it is recommended to put pieces of ice from the refrigerator into the cooler reservoir. However, such an «air cooler» does not solve the problem. Firstly, when freezing water, the refrigerator releases much more heat than the ice then takes it away when it melts. Secondly, with high humidity, the heat is much more difficult to tolerate. In terms of efficiency, this cooler is comparable to one serving of low-calorie ice cream or a glass of mineral water with ice.

In an ultrasonic humidifier, an ultrasonic generator creates a cloud of the finest water dust, which is carried out into the room. In terms of its parameters (energy consumption and performance), as well as its ability to cool the air, this device is close to a “cold steam” installation. Examples of ultrasonic humidifiers are Boneco 7035 and Burg BH-840E.

All humidifiers, regardless of the principle of operation, require maintenance. Manufacturers recommend washing the filters and disinfecting the water tank, as dust and dirt, which inevitably settle on the filters and dissolve in water, serve as an excellent breeding ground for bacteria. And if you do not take action, then the humidifier will turn into a «carrier».

Air purifiers-humidifiers

Manufacturers of climate equipment also produce combined devices that carry out both air purification and humidification. From the point of view of compatibility, the combination of an adsorption air purifier and a cold steam humidifier is ideal. In such systems, the air first passes through a system of dust and adsorption filters (activated carbon), then it is humidified and blown out by a fan. BIONAIRE INTERNATIONAL manufactures «serious» devices C-11, C-22, C-33, equipped with a contamination indicator, a tank capacity indicator, a humidity meter and automatic on / off.

The ingenious solution of the combined air cleaner-humidifier was proposed by the Swiss company AXAIR Ltd. In the Defensor PH-5 model, the air purified by the adsorption filter atomizes water, passing it through the porous carbon, and blows the water dust out by the fan. In the absence of water, this device works like an ordinary air cleaner.

An attempt to use water as a filter was made by the German company VENTA. «Air washer» Venta-Airwasher, according to manufacturers, not only effectively humidifies the air, but also cleans it from dust, microbes, heavy metals and tobacco smoke. The humidifier kit includes a bottle with Bio-Absorber liquid, with the help of which the device finally cracks down on bacteria. However, due to the insufficient adsorption capacity of water, the air-cleaning capabilities of such a device are rather reduced to collecting house dust, sulfur dioxide and ammonia, which is also not bad at all.

In conclusion, I would like to warn the reader. Improper use of a humidifier, like many other household appliances, can worsen living conditions. When the need for its use is beyond doubt (during a hot dry summer or winter heating season), a working humidifier creates a romantic feeling of a light sea breeze or a breeze from the river bank; sometimes it becomes the only salvation for an allergic person during an exacerbation of the disease. It makes sense to refrain from turning on the humidifier unless absolutely necessary, because dampness in the house is no less evil than dryness in the throat. In any case, it is best to use some kind of humidity meter and, depending on its readings, decide whether to humidify the air in the room or not.

Comparative characteristics of various household air humidifiers

• Source: Ideas for Your Home Magazine#33

Material prepared

Sergey Kanashenko

A photo

Dmitry Minkin