Augsburg Schaezlerpalais Mattes 2013-05-05 (23)

A humidifier is a device, primarily an

electrical appliance A home appliance, also referred to as a domestic appliance, an electric appliance or a household appliance, is a machine which assists in household functions such as cooking, cleaning and food preservation. Appliances are divided into three ty ...

, that increases

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

(moisture) in a single room or an entire building. In the home, point-of-use humidifiers are commonly used to humidify a single room, while whole-house or furnace humidifiers, which connect to a home's HVAC system, provide humidity to the entire house. Medical

ventilators A ventilator is a piece of medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilators ...

often include humidifiers for increased patient comfort. Large humidifiers are used in commercial, institutional, or industrial contexts, often as part of a larger HVAC system.

Overview

Humidification calculation

: Humidity per hour: X = ''

Air changes per hour Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air c ...

(ACPH) * M³ *

density of air The density of air or atmospheric density, denoted '' ρ'', is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperature a ...

* humidity ratio'' :: Humidity per day: X * 24 * The

air changes per hour Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air c ...

(ACPH) ranges wildly based on: **

Ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a m ...

: Values may be obtained from the HVAC maintainer that routinely (typically every third year or so) tests the ventilation of the residence. ** Insulation leakage: Measured with a standard blower door test. * Cubic meters: The volume of the room, excluding the

bathroom A bathroom or washroom is a room, typically in a home or other residential building, that contains either a bathtub or a shower (or both). The inclusion of a wash basin is common. In some parts of the world e.g. India, a toilet is typically ...

that should be kept closed since it ventilates humidity. *

Density of air The density of air or atmospheric density, denoted '' ρ'', is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in atmospheric pressure, temperature a ...

: Typically 1.2 for dry air. * Humidity ** Current relative humidity: 20% ** Humidity needed to reach 55%: 35% *** Humidity ratio for 35%: 0.0051 For example, a typical modern apartment of with closed windows (wood isolation) may consume to raise the relative humidity from 20% to 55%: 24 * 1,53 L/h (2*1×125×1.2×0.0051): * Air changes per hour ** Ventilation: 2 ** Insulation leakage: 1 (a few windows) * Cubic meters: 125 m³ (50 m² * 2.5 m height) *

: Typically 1.2 for dry air. * Humidity ** Current relative humidity: 20% ** Humidity needed to reach 55%: 35% *** Humidity ratio for 35%: 0.0051

Prevention of low indoor humidity

Low humidity may occur in hot, dry

desert climate The desert climate or arid climate (in the Köppen climate classification ''BWh'' and ''BWk''), is a dry climate sub-type in which there is a severe excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in deser ...

s, or indoors in artificially heated spaces. In winter, especially when cold outside air is heated indoors, the humidity may drop to as low as 10–20%. A relative humidity of 30% to 50% is recommended for most homes.

Health treatment

* Prevention of dermatitis: Low humidity can cause adverse health effects and may cause atopic dermatitis, and

seborrhoeic dermatitis Seborrhoeic dermatitis, sometimes inaccurately referred to as seborrhoea, is a long-term skin disorder. Symptoms include red, scaly, greasy, itchy, and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the ...

. **

Management of hair loss The management of hair loss, includes prevention and treatment of alopecia, baldness, and hair thinning, and regrowth of hair. Prevention Scratching of itchy scalp may contribute to hair loss. Health Body weight Prevention of obesity helps. O ...

: Commonly, patients with

experience mild redness, scaly skin lesions and in some cases

hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scar ...

. * Prevention of dry

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...

s and

cough A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three ph ...

: By drying out mucous membranes such as the lining of the nose and throat, it may also lead to a snoring problem, and can cause

respiratory distress Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...

. * Prevention of

dry eye syndrome Dry eye syndrome (DES), also known as keratoconjunctivitis sicca (KCS), is the condition of having dry eyes. Other associated symptoms include irritation, redness, discharge, and easily fatigued eyes. Blurred vision may also occur. Symptoms range ...

. * Improved

apparent temperature Apparent temperature, also known as feels like, is the temperature equivalent perceived by humans, caused by the combined effects of air temperature, relative humidity and wind speed. The measure is most commonly applied to the perceived outdoo ...

: The

heat index The heat index (HI) is an index that combines air temperature and relative humidity, in shaded areas, to posit a human-perceived equivalent temperature, as how hot it would feel if the humidity were some other value in the shade. The result is als ...

and humidex measure the effect of humidity on the perception of temperatures above . In humid conditions, the air feels much hotter, because less

perspiration Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distr ...

evaporates from the skin.

Improved climate for material

Low humidity can affect wooden furniture, causing shrinkage and loose joints or cracking of pieces. Books, papers, and artworks may shrink or warp and become brittle in very low humidity. In addition, static electricity may become a problem in conditions of low humidity, destroying semiconductor devices, causing

static cling Static cling is the tendency for light objects to stick (cling) to other objects owing to static electricity. It is common in clothing, but occurs with other items, such as the tendency of dust to be attracted to, and stick to, plastic items. ...

of textiles, and causing dust and small particles to stick stubbornly to electrically charged surfaces.

Negative impact of overuse of humidifiers

An indoor relative humidity of less than 51% resulted in significant reductions in mite and allergen levels. Overuse of a humidifier can raise the relative humidity to excessive levels, promoting the growth of

dust mites House dust mites (HDM, or simply dust mites) are various species of acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing allergies. Biology Species The curren ...

and mold, and can also cause

hypersensitivity pneumonitis Hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis (EAA) is a syndrome caused by the repetitive inhalation of antigens from the environment in susceptible or sensitized people. Common antigens include molds, bacteria, bird dropping ...

(humidifier lung). A properly installed and located

hygrostat A humidistat or hygrostat is an electronic device analogous to a thermostat but which responds to relative humidity, not temperature. A typical humidistat is usually included with portable humidifiers or dehumidifiers. It can also be included wi ...

should be used to monitor and control humidity levels automatically, or a well-informed and conscientious human operator must constantly check for correct humidity levels. A humidity below 50% can prevent water condensation on building materials. A

dehumidifier A dehumidifier is an air conditioning device which reduces and maintains the level of humidity in the air. This is done usually for health or thermal comfort reasons, or to eliminate musty odor and to prevent the growth of mildew by extracting w ...

can be used to balance the humidity.

Humidifiers

Industrial humidifiers are used when a specific humidity level must be maintained to prevent static electricity buildup, preserve material properties, and ensure a comfortable and healthy environment for workers or residents. Static problems are prevalent in industries such as packaging, printing, paper, plastics, textiles, electronics, automotive manufacturing and pharmaceuticals. Friction can produce static buildup and sparks when humidity is below 45%

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

(RH). Between 45% and 55% RH, static builds up at reduced levels, while humidity above 55% RH ensures that static will never build up. The American Society of Heating, Refrigerating and Air Conditioning Engineers (

ASHRAE The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE ) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration The term refrigeration refers to the ...

) has traditionally recommended a range of 45–55% RH in data centers to prevent sparks that can damage IT equipment. Humidifiers are also used by manufacturers of semiconductors and in hospital operating rooms. Printers and paper manufacturers use humidifiers to prevent shrinkage and paper curl. Humidifiers are needed in cold storage rooms to preserve the freshness of food against the dryness caused by hot temperatures.

Art museum An art museum or art gallery is a building or space for the display of art, usually from the museum's own collection. It might be in public or private ownership and may be accessible to all or have restrictions in place. Although primarily con ...

s use humidifiers to protect sensitive works of art, especially in exhibition galleries, where they combat the dryness caused by heating for the comfort of visitors during winter.

Natural humidifiers

Natural humidifiers don't use or need a demineralization filter because they water is slowly evaporated which leaves the mineral deposit at the bottom of the container. However, natural humidifiers raise the humidity very slowly even if their water surface area is big.

Common sources

* Human water losses, both respiratory, and insensible water loss like sweat, range in average 0.75 L/d in sedentary adults. However, most people do not spend most time of the day at home. *

Houseplant A houseplant, sometimes known as a pot plant, potted plant, or an indoor plant, is an ornamental plant that is grown indoors. As such, they are found in places like residences and offices, mainly for decorative purposes. Common houseplants are us ...

s may also be used as natural humidifiers, especially if they are placed in

fabric Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not th ...

flowerpot A flowerpot, planter, planterette or plant pot, is a container in which flowers and other plants are cultivated and displayed. Historically, and still to a significant extent today, they are made from plain terracotta with no ceramic glaze, w ...

s, since they evaporate water into the air through

transpiration Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth ...

. Care must still be taken to prevent bacteria or mold in the soil from growing to excessive levels, or from dispersing into the air. The presence of

sciarids The Sciaridae are a family of flies, commonly known as dark-winged fungus gnats. Commonly found in moist environments, they are known to be a pest of mushroom farms and are commonly found in household plant pots. This is one of the least studie ...

(like fungus gnats) in houseplants may indicate overwatering. * Hanging laundry will increase the humidity.

Homemade

One type of evaporative humidifier makes use of just a reservoir and

wick Wick most often refers to: * Capillary action ("wicking") ** Candle wick, the cord used in a candle or oil lamp ** Solder wick, a copper-braided wire used to desolder electronic contacts Wick or WICK may also refer to: Places and placename ...

. Sometimes called a "natural humidifier", these are usually non-commercial devices that can be assembled at little or no cost. One version of a natural humidifier uses a stainless steel bowl, partially filled with water, covered by a towel. A waterproof weight is used to sink the towel in the center of the bowl. There is no need for a fan, because the water spreads through the towel by

capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...

and the towel surface area is large enough to provide for rapid evaporation. The stainless steel bowl is much easier to clean than typical humidifier water tanks. This, in combination with daily or every other day replacement of the towel and periodic laundering, can control the problem of mold and bacteria.

Electric humidifiers

Droplets

= Evaporative humidifiers

= An "evaporative", "cool moisture", or "wick humidifier", consists of just three basic parts: a reservoir, a wick, and a fan. The wick is made of a

porous material A porous medium or a porous material is a material containing pores (voids). The skeletal portion of the material is often called the "matrix" or "frame". The pores are typically filled with a fluid ( liquid or gas). The skeletal material is us ...

that absorbs water from the reservoir and provides a larger surface area for it to evaporate from. The fan is adjacent to the wick and blows air onto the wet wick to aid in the evaporation of the water. Evaporation from the wick is dependent on

. A room with low humidity will have a higher evaporation rate compared to a room with high humidity. Therefore, this type of humidifier is partially self-regulating; as the humidity of the room increases, the water vapor output naturally decreases. These wicks become

mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...

y if they are not dried out completely between fillings, and become saturated with mineral deposits over time. They regularly need rinsing or replacement; if this does not happen, air cannot pass through them, and humidifier stops humidifying the area it is in and the water in the tank remains at the same level. Evaporative humidifiers function similarly to

evaporative cooler An evaporative cooler (also known as evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning s ...

= Impeller humidifiers

Impeller An impeller or impellor is a rotor used to increase the pressure and flow of a fluid. It is the opposite of a turbine, which extracts energy from, and reduces the pressure of, a flowing fluid. In pumps An impeller is a rotating componen ...

humidifiers (a type of cool mist humidifier) are usually noisier than others. It uses a rotating disc to fling water at a diffuser, which breaks the water into fine droplets that float into the air. The water supply must be kept scrupulously clean, or there is a risk of spreading bacteria or mold into the air.

= Ultrasonic humidifiers

An ultrasonic humidifier uses a ceramic diaphragm vibrating at an ultrasonic frequency to create water droplets that silently exit the humidifier in the form of cool fog. Usually the mist gets forced out by a tiny fan, while some ultra mini models have no fans. The models without fans are meant mainly for personal use. Ultrasonic humidifiers use a

piezoelectric transducer Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word '' ...

to create a high frequency (1-2 MHz) mechanical oscillation in a film of water. This forms an extremely fine mist of droplets about one micron in diameter, that is quickly evaporated into the air flow. Unlike the humidifiers that boil water, these water droplets will contain any impurities that are in the reservoir, including minerals from

hard water Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, bicarbo ...

(which then forms a difficult-to-remove sticky white dust on nearby objects and furniture). Any pathogens growing in the stagnant tank will also be dispersed in the air. Ultrasonic humidifiers should be cleaned regularly to prevent bacterial contamination from being spread throughout the air. The amount of minerals and other materials can be greatly reduced by using

distilled water Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, di ...

. Special disposable demineralization cartridges may also reduce the amount of airborne material, but the EPA warns, "the ability of these devices to remove minerals may vary widely." The mineral dust may have negative health effects. Wick humidifiers trap the mineral deposits in the wick; vaporizer types tend to collect minerals on or around the

heating element A heating element converts electrical energy into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element. Unlike the Peltier effect, this process is indepen ...

and require regular cleaning with

vinegar Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in ...

to control buildup.

Tanks

The water is usually supplied by manually filling the unit on a periodic basis.

= Top fill

= A top fill tank has a hole at the top to make it convenient to refill the tank on daily basis.

= Bottom fill

= Bottom filled humidifiers has removable water tank, often attached with a replaceable demineralization filter. Both the cap and the filter are often universal, which means that they can be switched between many tank cap humidifiers. Tank cap-based humidifiers are more inconvenient to fill than top fill tanks, because the demineralization filter has to be unscrewed and screwed back on a daily basis. Also, water drops from the tank attachment may get in contact with the hygrometer, which will make it harder to operate properly if they are not operated with caution.

Features

= Cleanable

= Ultrasonic wave nebulizers trap the mineral deposits over time, even if filters are used, and require cleaning with

to control buildup. It is easy to remove the buildup from the nebulizer in humidifiers with removable base parts. Other models must be screwed. Some models require monthly maintenance, while other models may run for years unmaintained.

= Activated charcoal filter

= Some humidifiers have an activated charcoal filter to reduce contaminants.

= Demineralization filter

= Humidity with mineral deposits build up on furniture, and static objects like computer monitors, TVs, etc. Most models with heating elements come with replacement demineralization filters (cartridges, or plastic foam, for the tank, and fabric near the heater in the reservoir) to reduce the amount of minerals entering the system. The cost of these filters is about $10-15 per cartridge or 10-pack for plastic foam, or fabric filters. Cartridges may last for 6 months, and plastic foam/fabric filters may last one month, if the humidifier is frequently used. Cartridges can be used for most humidifiers, but some models have a proprietary format. Some humidifiers (for example, some cold mist humidifiers) don't come with any filters at all. Clogged filters should be replaced when they cannot deliver water, which is indicated with a "no water" icon/alert signal in modern humidifiers. A manual way to figure out if a filter is clogged is to shake it, if the content of it (even if wet) doesn't move around, then it's unlikely that sufficient water will pass through.

= Heating element

= Steam humidifiers, or warm mist humidifiers, are equipped with a

. A medicated inhalant can also be added to the steam vapor to help reduce cough. Vaporizers may be healthier than cool mist types of humidifiers because steam is less likely to convey mineral impurities or microorganisms from the standing water in the reservoir. However, boiling water requires significantly more energy than other techniques. The heat source in poorly designed humidifiers can overheat, causing the product to melt, leak, and start fires.

= Ultraviolet germicidal irradiation (UVGI)

= Some humidifiers have an integrated

ultraviolet germicidal irradiation Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (ultraviolet C or UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unabl ...

(UVGI) feature.

= Water ionizer

= Some humidifiers have an integrated

water ionizer A water ionizer (also known as an alkaline ionizer) is a home appliance which claims to raise the pH of drinking water by using electrolysis to separate the incoming water stream into acidic and alkaline components. The alkaline stream of the tre ...

Maintenance

Sony_VPL-HS1_-_Delta_Electronic_Toto_TYF_300-J01-92424

torx Torx (pronounced ) is a trademark for a type of screw drive characterized by a 6-point star-shaped pattern, developed in 1967, Bernard F. Reiland, "Coupling arrangement and tools for same", filed 1967-03-21 by Camcar Textron. A popular generic ...

screwdriver is often needed to open

consumer electronics Consumer electronics or home electronics are electronic ( analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment, communications and recreation. Usuall ...

. Humidifiers with a

centrifugal fan A centrifugal fan is a mechanical device for moving air or other gases in a direction at an angle to the incoming fluid. Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such ...

may become noisy due to build up which cannot effectively be removed with vinegar for example. However, the fan can be replaced, and the model name of the fan and its specifications can be figured out by disassembling the humidifier and detaching it.

Fixed-installation humidifiers

For buildings with a

forced-air A forced-air central heating system is one which uses air as its heat transfer medium. These systems rely on ductwork, vents, and plenums as means of air distribution, separate from the actual heating and air conditioning systems. The return ...

furnace, a humidifier may be installed into the furnace. They can also protect wooden objects, antiques and other furnishings which may be sensitive to damage from overly dry air. In colder months, they may provide modest energy savings, since as humidity increases, occupants may feel warm at a lower temperature. Bypass humidifiers are connected between the heated and cold air return ducts, using the pressure difference between these ducts to cause some heated air to make a bypass through the humidifier and return to the furnace. Any humidifiers should usually be disabled during the summer months if air conditioning is used; air conditioners partially function to reducing indoor humidity, and having a humidifier continue to operate will waste significant amounts of energy.

Drums

Drum style (bypass) uses a pipe to bring water directly to a reservoir (a pan) attached to the furnace. The water level in the pan is controlled by a

float valve A ballcock (also balltap or float valve) is a mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and (in the event of low water pressure) backflow. The modern ballcock was invented by J ...

, similar to a small

toilet A toilet is a piece of sanitary hardware that collects human urine and feces, and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry or non-flush toilets do not. They can be designed for a sitting position popu ...

tank float. The wick is typically a foam pad mounted on a drum and attached to a small motor; hot air enters the drum at one end and is forced to leave through the sides of the drum. When the

calls for humidity, the motor is turned on causing the drum to rotate slowly through the pan of water and preventing the foam pad from drying out. :Advantages include: :* Low cost :* Inexpensive maintenance (drum-style pads are cheap and readily available) :Disadvantages include: :* Requirement for frequent (approximately monthly) inspections of cleanliness and pad condition :* Water evaporation even when humidification is not required (due to the pan of water which remains exposed to a high

velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...

air stream) :*

Mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...

growth in the pan full of water (this problem is exacerbated by the large quantity of air, inevitably carrying mold spores, passing through the humidifier whether in use or not). For the latter reason especially, drum-style humidifiers should always be turned off at the water supply during summer (air conditioning) months, and should always be used with high quality furnace

air filter A particulate air filter is a device composed of fibrous, or porous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may a ...

s (

MERV Merv ( tk, Merw, ', مرو; fa, مرو, ''Marv''), also known as the Merve Oasis, formerly known as Alexandria ( grc-gre, Ἀλεξάνδρεια), Antiochia in Margiana ( grc-gre, Ἀντιόχεια ἡ ἐν τῇ Μαργιανῇ) and ...

ratings as high as possible to ensure small numbers of mold spores reaching the humidifier pan) when the water supply is turned on.

Disc wheels

A disc wheel style (bypass) is very similar in design to the drum style humidifiers; this type of furnace humidifier replaces the foam drumming with a number of plastic discs with small grooves on both sides. This allows for a very large evaporative surface area, without requiring a great deal of space. Unlike the drum style humidifiers, the disc wheel does not need regular replacement. :Advantages include: :* Very low maintenance (basin of humidifier should be cleaned out periodically, unless an automatic flushing device is installed) :* No regular replacement of parts necessary :* Higher output due to large evaporative surface area :* Can be installed in hard water situations :* Maintains efficiency throughout lifespans :Disadvantages include: :* Higher price :* Water evaporation even when humidification is not required (due to the pan of water which remains exposed to a high velocity air stream)

Bypass flow-through

Bypass flow-through style (bypass – also known as "biscuit style" or many other, similar variant names) uses a pipe to bring water directly to an electrically controlled valve at the top of the humidifier. Air passes through an aluminum "biscuit" (often called a pad; the term "biscuit" emphasizes the solid rather than foamy form) which is similar to a piece of extremely coarse steel wool. The "biscuit" has a coating of a

matte Matte may refer to: Art * paint with a non-glossy finish. See diffuse reflection. * a framing element surrounding a painting or watercolor within the outer frame Film * Matte (filmmaking), filmmaking and video production technology * Matte p ...

ceramic, resulting in an extremely large surface area within a small space. When the hygrostat calls for humidity, the valve is opened and causes a spray of water onto the "biscuit". Hot air is passed through the "biscuit", causing the water to evaporate from the pad and be carried into the building. :Advantages include: :* Reduced maintenance (new "biscuit" is needed only when clogged with dust or mineral deposits, typically once per year) :* Lack of a pan of potentially stagnant water to serve as a breeding ground for mold as with a drum-style humidifier :* No incidental humidification caused by a constantly replenished pan of water in a high velocity air stream :* Reduced requirement for expensive air filters :* Uses little electricity :Disadvantages include: :* A somewhat higher purchase price :* Manufacturer and model-specific replacement biscuits (versus the relatively generic drum-style pads) may be more expensive and difficult to find :* For most models, a portion of the water supplied to the unit is not evaporated. This can generate a considerable amount of waste water containing residual minerals, which does require connection to a drain. There is a limited selection of drain-less models that recirculate water, but mineral buildup must then be removed manually on a periodic basis.

Spray mist

Spray mist type uses a pipe, usually a small plastic one, to bring water directly to an electrically controlled valve (atomizer-this forces the water through a tiny orifice causing it to break up into tiny particles) in the humidifier. Water mist is sprayed directly into the supply air, and the mist is carried into the premises by the air flow. :Advantages include: :* Simpler than bypass types to install, requiring a single cut hole for installation, no additional ducting. :* Uses little electricity. :* Small, compact unit which fits where other types cannot. (Approximately square.) :* Because it does not require bypass ducting it does not undermine the pressure separation (and therefore, blower efficiency) of the return and supply ducts. :* Does not require use of moisture pads (on-going expense). :* Highly efficient usage of water. Does not generate waste water, and does not require separate connection to a drain. :* Requires little maintenance. Periodic cleaning of nozzle may be required in hard water environments. :* Lack of a pan of potentially stagnant water to serve as a breeding ground for mold as with a drum-style humidifier. :Disadvantages include: :* Spray nozzle can become clogged in hard water situations, necessitating the use of water filter, periodic cleaning of nozzle, or nozzle replacement. :* Disperses any minerals in the water into the airstream.

Additional types

There are many different types of Plant and Home Humidifiers which can help you to maintain humidity level of your home as required. Additional types include non-bypass flow-through (fan augmented), steam, impeller or centrifugal atomizer, and under duct designs.

Problems

The U.S. EPA provides detailed information about health risks as well as recommended maintenance procedures. If the tap water contains a lot of minerals (also known as "hard water") then the ultrasonic or impeller humidifiers will produce a "white dust" (calcium is the most common mineral in tap water), which usually settles onto furniture, and is attracted to static electricity generating devices such as CRT monitors. The white dust can be prevented by using distilled water, or a demineralization cartridge in ultrasonic humidifiers. Bottled waters labeled "natural", "artesian", or "spring" may still have their original mineral content. The EPA reports that ultrasonic and impeller humidifiers spread the most mineral deposits and microorganisms, while evaporative and steam humidifers can allow the growth of microorganisms but generally disperse less of them into the air., In addition, a stuck or malfunctioning water supply valve can deliver large amounts of water, causing extensive water damage if undetected for any period of time. A water alarm, possibly with an automatic water shutoff, can help prevent this malfunction from causing major problems. From 2006 to 2011, the disinfectant polyhexamethylene guanidine was used as a cleaning agent for humidifier water tanks in Korea, leading to severe lung disease. Eighty children died of the disorder and nine adults either died or needed lung transplants. In the two years following the banning of cleaning chemicals for humidifier tanks, there were no new cases.

References

External links

EPA.gov
Indoor Air Facts No. 8 Use and Care of Home Humidifiers {{Authority control Home appliances