Germ free humidifier: Honeywell Germ Free Cool Moisture Humidifier Review (2023 Update)

Honeywell Germ Free Cool Moisture Humidifier Review (2023 Update)

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Today we’re talking about my review of the Honeywell Germ-Free Cool Moisture humidifier! It’s easily one of the most popular humidifiers out there, and I’m breaking down every single component – sharing how the humidifier works, where to put it in a room, how to use it and how to keep it clean!

The “germ-free” feature on this humidifier is a UV light that helps destroy bacteria, germs, and mold that may end up in the water that turns into the cool moisture in one’s room. This is excellent for peace of mind and is just one addition to an already awesome humidifier.

What else do I love about it and what else is there to consider before purchasing? There’s a lot – so watch my full video review or keep reading and scrolling for my write-up!

The Honeywell Germ Free Cool Mist Humidifier is a great addition to any medium-sized bedroom and can run for up to 24 hours on its slowest fan speed.

Mattress Clarity Score

4.40 / 5

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Key Features

  • Dimensions (LxWxH): 17.48″ x 9.37″ x 11.85″
  • Weight: 8.36 lbs
  • The humidifier utilizes a self-regulating evaporative system to add invisible cool moisture to the air
  • Uses a UV light as part of the brand’s patented germ-killing process and continuously kills up to 99.9% of water-bred germs, bacteria, mold, and spores in the water
  • 3-speed settings to adjust moisture output and sound level
  • Room size: Medium (about 400 sq feet or 19 ft x 19 ft room)
  • Moisture type: invisible cool moisture
  • Tank capacity: 1.1 gallon
  • Run time per filling: up to 24 hours (on low speed)
  • Price: around $60, depending on the retailer
  • 3-year limited warranty

How the Honeywell Humidifier Works

Once the filled water tank is in place, water is delivered to the UV and wicking systems. When the unit is on, the water moves very slowly past the UV system. This is ample time to destroy germs, fungus, and mold that may be present in the water. The water is then delivered to the filter/wick. This saturated wick not only filters the air but also provides moisture to the humidifier fan, which in turn, delivers germ-free moisture to the room.

How to Use the Humidifier

Here are the use instructions according to Honeywell:

Select a firm, level location at least 6” (15 cm) from any walls and furniture for proper airflow. Place the humidifier on a water-resistant surface, as water can damage furniture and some flooring.

  1. Remove the water tank and fill with water
  2. Lift off the upper enclosure/housing unit
  3. Remove the wicking filter and soak in cool water
  4. Replace the wet filter in the base of the unit and reassemble
  5. Place the upper enclosure back on the base
  6. Fill the tank with water and replace the filled tank in unit
  7. Make sure the unit is off
  8. Plug the unit into a 120v outlet
  9. Set fan speed


  • Easy to use and easy to clean, especially compared to other humidifiers
  • The UV light that kills bacteria is a nice touch and provides good peace of mind
  • No annoying lights
  • Quiet sound, not disruptive
  • Humidifies decent sized rooms; should work well in kid’s rooms
  • Reasonably priced and available at multiple retailers


  • Needs frequent maintenance
  • Wick needs to be kept damp and changed every 1-2 months at an added cost
  • The wicking filter has been personally difficult to locate in order to purchase; not easily available in-store or online, so I’d stock up
  • The UV light will need to be replaced at some point so keep the number from the booklet since users will need to call them and remove the bulb in a specific way

My Experience

I love the simple nature of this Honeywell humidifier and I think the germ-free feature is an added bonus to what is an already solid machine. It is basically four parts, two of which are easy to clean and can be thrown in the dishwasher and only one that needs consistent attention (the wicking filter).

What the machine takes up in size – compared to other models – it makes up for in functionality. I love the quiet noise, the lack of bright distracting light, the multiple fan speeds, and the self-regulating humidity evaporative system. The water tank is extremely easy to use and to re-fill and lasts on a low setting for at least 24 hours, which means I don’t have to deal with it every day!

In my house, we have three humidifiers going during the winter, which means I’m cleaning humidifiers in bulk at the end of every week to ensure that everything is staying sanitized and operating properly. The Honeywell Germ-Free humidifier is the easiest machine to clean; I simply place the water tank (without cap) and the base in an empty dishwasher and follow the setting directions to clean that. The housing unit that features the actual electrical motor just needs to be wiped down occasionally.

The only real component I have to deal with is the wicking filter. I was initially frustrated with the filter because I could not find it at my local CVS, Walgreens, Target or Home Depot (where they are sold) and it was back-ordered on Amazon, a testament to how popular this machine is. Therefore, I had to order them off the Honeywell website, so I made sure to order several so I could have them available when I needed to replace them. At around $10-$13 a pop, it adds up, but I think there is still a lot of value in the machine. I use distilled water to help reduce the mineral build-up, which lessens the frequency with which I have to replace the filter.

I would recommend this humidifier for adult rooms or kids’ rooms, as long as they’re not much larger than 400 sq feet. I agree with the masses, there’s a reason why this humidifier is so popular!

Keeping the Humidifier Clean

If the humidifier is being used daily, the entire humidifier should be cleaned weekly, and the wick should be changed out every 1-2 months. Some parts can be thrown into the dishwasher to clean:

  • Water tank (no cap)
  • Base

Per Honeywell’s instructions, place the two pieces on the top rack of an empty dishwasher, don’t use detergent and keep the temperature to below 158 °F on a regular or light cycle.

Scale Removal

If no dishwasher is available, the machine will need to be de-scaled by hand. Scaling occurs when hard water is used and minerals build up within the machine – it’s crucial that this step is completed. Follow the brand’s instructions that can be found on their website or in the documentation that comes with the humidifier.

  1. Turn off and unplug the unit
  2. Remove and empty water tank
  3. Lift off upper enclosure
  4. Remove filter
  5. Wipe the base, tank cap and tank with distilled white vinegar/undiluted vinegar
  6. Rinse thoroughly

Disinfecting with Bleach

The humidifier will need to be disinfected with bleach in addition to having the scale removed from mineral build-up.

  1. Turn off and unplug the unit
  2. Remove and empty the water tank
  3. Lift off upper enclosure
  4. Remove the filter
  5. Fill the water tank with 1 tsp of bleach and 1 gallon of cool water
  6. Wipe the base with the same solution
  7. Rinse everything until the smell of bleach is gone

Caring for the Filter

The filter is called a HAC-504 series replacement Filter A and needs to be replaced every 1-2 months or if it starts to smell, looks extremely discolored or starts to feel crusty. While customers should be able to purchase the filter at a variety of retailers, the only place I had luck locating one was on the Honeywell website, where shipping takes a decent amount of time. I recommend purchasing multiple filters in advance so it’s easy to replace it when needed.

Sleep Benefits of Humidifiers

When it comes to sleep, the main job of a humidifier is to add moisture to the air, which prevents irritation and congestion that results from increased dryness. Dry air can be a natural part of a home thanks to the region of the country it’s in or it may come from turning the heat on in the house for the first time. People, especially young children, may benefit from moisture in the air to help combat allergies or sensitivities.

For adults and kids, this can mean better sleep simply because they’re not waking up with a dry or scratchy throat, and their nasal passages will stay moist and help filter out bacteria and allergens. Plus it’ll help prevent nosebleeds, which can be a huge sleep disruptor at night.

The Honeywell Germ Free Cool Mist Humidifier is a great addition to any medium-sized bedroom and can run for up to 24 hours on its slowest fan speed.

Mattress Clarity Score

4.40 / 5

Read Full Review

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Final Thoughts

Those are the full ins and the outs of this awesome humidifier! This is a great, affordable and easy-to-clean option for anyone who is ready to dive into the world of cool mist humidifiers. If there are any questions, shoot them in the comments of the YouTube video and I’ll look as soon as I can!


Is a Honeywell humidifier good?

Honeywell has an excellent reputation for producing high-quality humidifiers. Their Germ-Free Cool Moisture humidifier is one of their most popular, if not their most popular model with extremely high reviews across multiple retail platforms.

How often should I clean my humidifier?

If using consistently, clean the whole thing – scale and disinfecting weekly.
How often to change the filter: It is recommended that people change their filter every 1-2 months, depending on water quality and usage.
Any of the following conditions indicate that it is time to replace the Wicking Filter:

  • It is hard and crusty
  • It develops an odor
  • Moisture output is decreased

Where should I put my humidifier?

Select a firm, level location at least 6” (15 cm) from any walls and furniture for proper airflow. Place the humidifier on a water-resistant surface, as water can damage furniture and some flooring.

Can I use the Honeywell humidifier without a filter?

No, this specific humidifier requires a wicking filter and uses the HAC-504 series replacement Filter A model.

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Katie Golde

Katie previously managed the day to day operations of the Mattress Clarity news site and reviews sleep products in addition to writing and editing sleep news.
She hails from Austin, where she lives with her growing family. She is a Certified Sleep Science Coach and has a master’s degree in Journalism from Northwestern University and has a background in health and science content. Her work can be found in print and online publications like Discover Magazine, USA Today and The Huffington Post.

Honeywell Germ Free Cool Mist Humidifier

Last updated date: December 23, 2020

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Show Contents


  1. Our Take
  2. Features
  3. Specifications
  4. From The Manufacturer
  5. Expert Reviews
  6. Overall Ranking
  7. Our Home Humidifier Buying Guide
  8. Our Home Humidifier Tip and Advice

We looked at the top Home Humidifiers and dug through the reviews from some of the most popular review sites. Through this analysis, we’ve determined the best Home Humidifier you should buy.

Update as October 19, 2021:
Checkout The Best Home Humidifier for a detailed review of all the top home humidifiers.

Overall Take

Honeywell’s Germ Free Cool Mist model is a great all-around humidifier that’s quiet, efficient and affordable. It’s a smart choice for a baby’s room, although the antibacterial components also make it suitable for people with allergies. The only major drawback is that it doesn’t feature auto shut-off, but that’s not a dealbreaker if you’re willing to keep an eye on the time.

In our analysis of 40 expert reviews, the Honeywell Germ Free Cool Mist Humidifier placed 11th when we looked at the top 16 products in the category. For the full ranking, see below.

From The Manufacturer

Honeywell Germ Free Cool Mist Humidifier

Expert Reviews

Expert Summarized Score

7 expert reviews

User Summarized Score

4,855 user reviews

What experts liked

We’d recommend the Honeywell HCM-350 in a baby’s room for the same reasons we’d choose it for any other room: It’s easier to live with than almost any other humidifier, and it performs better than most of them, too.

– New York Times Wirecutter

July 5, 2018 | Full review

The Honeywell HCM-350 Germ-Free Cool Mist Humidifier is a quiet, efficient, easy-to-use humidifier for larger rooms that both experts and owners say is a good all-around pick.

– The Spruce

| Full review

It is a good humidifier for a baby or if you have other young children in the home.

– Top Ten Reviews

| Full review

The Honeywell HCM-350 provides good all-around performance in a package that is very easy to clean.

– Tech Gear Lab

September 26, 2017 | Full review

Output performance was excellent.

– Consumer Reports

| Full review

Its easy-to-use design makes the filling and cleaning a breeze, letting you worry about your daily activities instead of monitoring the unit.

– HouseholdMe

| Full review

The water tank has a smooth bottom design and the handle is one of the most comfortable and well balanced on the market.

– Indoor Breathing

| Full review

What experts didn’t like

One last “flaw” is that the utilitarian design is probably not going to complement the aesthetic some parents may choose for a child’s nursery.

– New York Times Wirecutter

July 5, 2018 | Full review

An ultraviolet light inside the unit aims to kill any mold, fungus, or bacteria, though experts say this feature is probably overblown.

– The Spruce

| Full review

This missing safety feature means you have to be vigilant of when to turn the machine off manually, or it may overheat from running on an empty tank.

– Top Ten Reviews

| Full review

However, it requires replacement filters that push its lifetime cost above that of some of the premium models we tested.

– Tech Gear Lab

September 26, 2017 | Full review

Hard Water performance was good. Lacks an indicator showing when the tank is empty.

– Consumer Reports

| Full review

Large size, no auto shut off

– Indoor Breathing

| Full review

1. Pure Enrichment MistAire Ultrasonic Humidifier

Overall Score: 9. 6

2. Everlasting Comfort Ultrasonic Cool Humidifier, White

Overall Score: 9.2

3. Miroco 26dB Ultrasonic Cool Mist Home Humidifier

Overall Score: 9.1

4. Homech Ultrasonic Cool Mist Home Humidifier

Overall Score: 9.0

5. LEVOIT Humidifiers Ultrasonic Humidifier Whisper Quiet

Overall Score: 8.6

6. Everlasting Comfort Ultrasonic Cool Humidifier, Black

Overall Score: 8.4

7. Honeywell Cool Moisture Console Humidifier

Overall Score: 8.2

8. HoMedics Cool Mist Ultrasonic Humidifier

Overall Score: 8.0

9. LEVOIT Cool Mist Humidifier

Overall Score: 8.0

10. BONECO Travel Cool Mist Humidifier

Overall Score: 8.0

11. Honeywell Germ Free Cool Mist Humidifier

Overall Score: 8. 0

12. Air Innovations MH-408 Humidifier

Overall Score: 7.9

13. TaoTronics Cool Mist Ultrasonic Humidifier

Overall Score: 7.9

14. Venta Airwasher LW25 Humidifier

Overall Score: 7.9

15. Crane Drop Humidifier

Overall Score: 7.1

16. Hupro Ultrasonic Cool & Warm Mist Home Humidifier

Overall Score: 7.0

Anyone who’s struggled through chilly days with cracked lips or burned through jars of lotion during colder months has experienced the effects of dry air. When the air in your home or apartment is too dry, it affects your skin and mucous membranes. This can dry out and irritate your skin, aggravate your sinuses and contribute to coughs and colds. Overly dry air also increases static electricity in your hair and clothes, and it makes cold rooms seem even chillier. Humidifiers reduce these negative effects by adding moisture to the air in your home.

There are several types of humidifiers. Central humidifiers are built into your air conditioning or heating unit, and they generally do a good job of maintaining healthy moisture levels in your air. However, older homes, apartments or homes in very cold, dry climates might need a boost of humidity from portable humidifiers.

Portable humidifiers use different methods to add moisture to cold, dry rooms. Evaporative humidifiers, like the Everlasting Comfort Ultrasonic Cool Humidifier, Black, are the most common type. They have a reservoir that dispenses water through a wicking filter into a basin, then a fan blows air through the moistened filter to dispense small water droplets throughout the air.

Ultrasonic humidifiers use ultrasonic vibrating diaphragms to force tiny drips of water into your air. They tend to be quieter than other humidifiers.

Both evaporative and ultrasonic humidifiers need to be cleaned regularly to prevent mold, minerals and bacteria from growing in the water basin. However, some higher-end ultrasonic humidifiers have built-in UV light filters that sanitize your water before it’s exposed to air.

Most modern portable humidifiers use evaporative or ultrasonic technology. Cool mist versions of these humidifiers are also becoming more popular. They emit room-temperature water droplets into the air instead of warm water, making them more suitable for year-round use than steam humidifiers.

After you’ve covered your humidifier basics, there are a few more considerations you’ll want to make before selecting the best unit for your home.

  • Take a look around your home to determine the safest spot for your humidifier. You should make sure to keep it off the floor on a sturdy surface that leaves several inches between the humidifier and your wall and outlets.
  • How much elbow grease are you willing to put into cleaning your humidifier? You’ll need to keep the interior squeaky clean to prevent mineral and mildew buildup. Some options have UV lights to sanitize your water and dishwasher-safe basins to get into every nook and cranny. However, you’ll have to pay more for these features.
  • Using distilled water instead of tap water can help slow down or prevent mold and mildew growth in your humidifier. It can also help your filter last longer and keep the humidifier other components in better condition.
  • How large is your room or apartment? Some units are best for small to medium-sized rooms. You might have to buy more than one small unit if you need to increase humidity in multiple rooms. Larger humidifiers can help out in multiple rooms or even your whole house.
  • Who will be using the humidifier? You’ll want a whisper-quiet model for your baby’s nursery. If you’re relying on a humidifier to help alleviate symptoms of asthma or allergies, an ultra-hygienic option might be right up your alley.
  • Some humidifiers have very large capacity tanks. This is great if you need a humidifier that lasts through the night without shutting off. However, if filling a large tank will be physically difficult for you or another person using the humidifier, you’ll want a smaller option.
  • How many hours would you like your humidifier to run? Some humidifiers can run for up to 30 hours on low, so you can set it and forget it for half the weekend.

Checkout Our Other Buying Guides

What is legionellosis and where does it come from

Air conditioners

Ultrasonic humidifiers

Conventional humidifiers (air wash)

Duct sprayers (sprinklers)

Steam generators

Direct Spray Humidification

Legionellosis is an acute infectious disease caused by microorganisms of the genus Legionella. Mostly detected as severe pneumonia, although it is much more common as a mild respiratory infection. Infection occurs by inhalation of vapors or drops of water containing legionella. With a mild variant of the course, an erroneous diagnosis of ARVI is most often made, according to some reports, up to 10% of cases of a diagnosed viral respiratory infection are actually manifestations of legionellosis. In the European Union, among cases of pneumonia with an established etiological agent, legionellosis accounts for 5.4 to 20% of cases.

The name of the genus of bacteria is associated with the 1976 outbreak in Philadelphia of a severe respiratory disease after the convention of the American Legion.

Legionella are rods 0.5 to 0.7 microns in diameter and 5 microns long. They survive at temperatures from 5°C to 55°C, actively reproduce at 20–40°C, and the optimum temperature is 35°C. They require L-cysteine ​​and soluble iron pyrophosphate (Fe ++) to grow. They can survive in tap water for up to a year, and in distilled water for 2-4 months.

Legionella are distributed throughout the world. The natural habitat is fresh water, but poor maintenance of air conditioning and humidification systems, as well as fountains, leads to infection of people, since infection occurs by inhalation of water vapor containing legionella.

Air conditioners

Condensation accumulates on the surfaces of the air conditioning system, which, when heated, becomes a suitable breeding ground for legionella. Together with the cooled air, bacteria enter the room.

Modern air conditioners, when properly designed, installed and regularly maintained, do not pose a danger.

Ultrasonic Humidifiers

The most dangerous type of humidifier. At the bottom of a vessel with water is a piezoelectric element, which, under the influence of an alternating current, oscillates at a very high frequency. Droplets break off from the surface of the water, which are carried away by the fan into the air of the room. During operation, the piezo element heats up, creating ideal conditions for the reproduction of legionella. The use of distilled water does not save: bacteria enter the humidifier from the air.

Microbiological safety can be achieved by constantly circulating water through the UV sterilizer, but this option is extremely rare.

The water tank in most devices of this type is difficult to rinse. Biocides should be used to protect against legionella and other bacteria, but they are not safe on their own.

Ultrasonic duct humidifiers are built into ventilation. The problem of microbiological safety is not removed, they need to periodically flush the water tank with biocides. In addition, the design includes another place for the reproduction of microorganisms – the ventilation channel, which requires professional antibacterial treatment.

Traditional humidifiers

Air humidification occurs by blowing air through a set of discs (in the case of disc humidifiers) or hygroscopic material. Bacteria enter the air, coming off together with microdrops from the edges of the wetted planes.

To reduce the risk of bacteria spreading, use decontaminated water and flush the system regularly.

Duct spray humidifiers (atomizers, sprinklers)

Drift eliminators in duct spray humidifiers provide a convenient breeding ground for legionella. Preliminary water purification does not solve the problem due to the possibility of contamination from incoming air. The ultraviolet irradiation of air chambers kills bacteria, but often leads to the formation of ozone, which is a poison.

Steam generators

Boiling water kills legionella, but in ducted steam generators there is a high chance of bacteria developing in the air ducts. To reduce the risk of bacteria spreading, regular cleaning and disinfection of air ducts is essential. Steam generators with direct steam outlet to the room are completely protected against the spread of legionella.

Direct spray humidification

Direct spray humidification systems are among the safest. Some bacteria colonize the system if it is turned off for several days or more. As a rule, legionella is not there anyway, since they have nowhere to come from if the water passes high-quality filtration. For this type of system, quality filtration becomes a key factor.

To completely prevent the entry of legionella into the air in the humidification system Universe the following technical solutions apply:

  • The water is pre-treated in an ultrafiltration membrane and in a double reverse osmosis system, which removes bacteria, viruses and organic compounds from the water.
  • Just prior to spraying, the water additionally passes through the sterilizing UltraFilter.
  • After cleaning, the humidifying water does not come into contact with air until spraying, to protect against contamination by microorganisms.
  • Daily flushing of all elements of the system to prevent the formation of stagnant zones.
  • Even after a long period of inactivity, flushing is enough for further normal operation, since the tubes inside are self-cleaning. The inner surface of the tubes is made of Teflon ® – the most slippery substance in the world, to which nothing sticks.

    what is it, what are the symptoms, where does it live. Legionellosis and humidifier.

    Legionella is a saprophytic bacterium that obtains its required substances from decaying organic materials. Legionella require the amino acid L-cysteine ​​and iron ions Fe++ to grow. Bacteria are rods with a diameter of 0.5 – 0.7 microns and a length of about 5 microns, sometimes there are variants up to 25 microns long. The ideal temperature for bacteria to grow is between 25°C and 45°C, and the pH of the water is between 5 and 7; the life of the bacterium is about 12 months.

    The presence of legionella bacteria in water is not the same as a dangerous infection. In fact, more than 50 Legionella species are known, of which approximately 22 are human pathogens.

    Legionella pneumophila is the most common cause of disease. There are two most common pathological outcomes of infection with this bacterium: Pontiac fever, which is often misdiagnosed because it has similar symptoms to the flu; the second, much more serious and dangerous, is legionnaires’ disease, a special form of pneumonia with a mortality rate of up to 15%.


    In 14% of cases, if influenza or acute respiratory infections are diagnosed, the real causative agent of the disease is legionella!

    In 2% of cases, if chronic bronchitis is diagnosed, the causative agent of the disease is Legionella!

    Additional articles:

    The role of legionellosis in human infectious pathology (Tartakovsky I. S., Sinopalnikov A.I., journal “Sanitary doctor” No. 9 2009, PDF)

    Prevention of legionellosis (Sanitary epidemiological rules of the joint venture, PDF)

    Legionellosis (Shcherba Yu.V., Shalginskaya E.G., Polyclinic magazine No. 3 2008, PDF)

    Legionnaires’ disease The two most common clinical conditions are Pontiac Fever and Legionnaires’ Disease.

    Pontiac fever , after an incubation period of 24 to 28 hours, is acute, does not affect the lungs, is flu-like, and lasts 2 to 5 days. Symptoms: general discomfort, muscle pain and headache, often accompanied by fever, sometimes cough and sore throat. Fever may be accompanied by diarrhea, nausea, and mild neurological symptoms such as dizziness or photophobia.

    Legionnaires’ disease , after an incubation period of 2 to 10 days (5 to 6 days on average), presents with moderate to severe pulmonary complications. The first symptoms are usually discomfort, headache, fever, and mild cough, which are complicated by more severe respiratory symptoms.

    Where does legionella live? Where can you get legionellosis?

    Legionella normally lives in water temperatures between 5°C and 55°C. The breeding range is from 20°C to 50°C. Legionella is sown from air conditioner fluids, industrial and domestic cooling systems, boilers, showers, respiratory therapy equipment. It breeds in fast water heater pipes, hot water tanks and water pipes. Legionella colonies are approximately 1 mm in size and can be dispersed over long distances by spraying water with 2-3 mm droplets. This is why various water spray devices (showers, hot tubs, humidifiers, and other sprayers) can spread bacteria naturally if the water they spray contains these bacteria.
    The main ways of transmission of legionellosis are airborne and airborne. The main factor in the transmission of legionellosis is considered to be a fine bacterial aerosol, that is, the spraying of bacteria along with contaminated water or dust. Therefore, all humidification devices, where water is contained in a stagnant container or circulates through a circulating circuit, are also a potential hazard, especially if the water container comes into contact with air, from where bacteria can enter the water, even if it was initially disinfected.

    The main risk factors for various microclimate systems:

    Air conditioners – Central air conditioning systems with external irrigation systems are of particular danger, in which disinfection work is not carried out in a timely manner. For domestic air conditioners, it is sometimes possible for legionella to grow in the condensate on the surfaces of the plate heat exchangers and the drain pan, especially for non-inverter models (in which the temperature of the wet plates periodically becomes room temperature). “Cold from the air conditioner” can just be caused by the inhalation of Legionella against the background of weakened local immunity.

    Ultrasonic humidifiers of all types is the most dangerous type of humidifier, without the use of special biocides, the growth of microorganisms in a container with water, under the bottom of which ultrasonic emitters are located, is almost inevitable. Bacteria, together with the formed microdroplets of water, enter the air and spread throughout the room. Unfortunately, preliminary water purification does not give the full effect, since the air in contact with water can be a source of bacterial contamination.

    Ducted steam generators – in case of improper design, condensation can form on the inner walls of the ducts, especially at branches and bends, which serves as a breeding ground for bacteria. Legionella enter the air stream after the condensate has dried, along with the damp dust remaining in its place, that is, after a long period of humidification has ended.

    Traditional humidifiers (room or duct) – legionella growth occurs in a container of water, and the spraying of bacterial aerosol into the air is observed as a result of the detachment of microdroplets of water at the edges of the wetted planes or together with dust formed in place of dried water. Infection of a container with water, as a rule, occurs from air in contact with water.

    Duct spray humidifiers (atomizers, sprinklers) – a very dangerous solution due to the growth of legionella on drop eliminators. Pre-treatment of water does not give a significant effect due to the likelihood of constant contamination from incoming air. The use of ultraviolet irradiators of air chambers, solving the problem of bacterial contamination, can lead to the formation of ozone, which is a poison.

    Direct Spray Humidifiers – Although they are among the safest in terms of protection against legionella, however, during long periods of interruption in work with a complete shutdown of the system, they can create conditions for the growth of other bacteria and their subsequent spread into the air. Therefore, it is strongly not recommended to disconnect such systems from the network for a long time, as this will form zones of stagnant water. In normal mode, the system constantly purifies and sterilizes water, and also performs constant flushing to eliminate zones of stagnant water.

    The only type of humidifier that provides a full guarantee of protection against legionella is a steam generator with direct, without air supply, steam supply to the room, household floor or stationary wall versions. In this case, hot steam from boiling water immediately enters the air of the room, as, for example, occurs in a Turkish sauna (hamam). Unfortunately, such devices have significant drawbacks – the noise of boiling water, high energy consumption, hot steam output, as well as the need for constant topping up of water (for household floor models).

    What measures can be taken to prevent the risk of legionella spread?

    Measures to reduce the risk of spreading bacteria

    through air conditioners and humidifiers:

    color indicates the degree of total potential risk

    1. Central air conditioners:

    • exclusion of the ingress of air that has been in contact with external sprinklers into the air intake
    • use of biocides for cooling water
    • complete condensate drain from cooling sections

    2. Ultrasonic household humidifiers:

    • use of purified and disinfected water
    • regular emptying of water from the tank
    • periodic flushing of the water tank with biocides

    3. Traditional humidifiers based on hygroscopic materials (sponge, honeycomb):

    • reduction of air flow rate and elimination of possible local turbulences
    • use of purified and disinfected water
    • exclusion of recycled water, permanent drain to drain
    • use of low volatile biocides

    4. Ultrasonic duct humidifiers:

    • use of purified and disinfected water
    • continuous circulation of water through the UV sterilizer
    • regular discharge of water into the drain
    • periodic flushing of the water tank with biocides

    5. Traditional household humidifiers (air washers):

    • use of purified and disinfected water
    • continuous circulation of water through the UV sterilizer
    • Regular draining of tank water
    • periodic flushing of the water tank and discs using biocides

    6. Household air conditioners:

    • using inverter models to ensure the constant temperature of the heat exchanger plates
    • correct installation for complete and rapid condensate drainage
    • periodic disinfection of the surface of the heat exchanger plates

    7. Duct steam generators:

    • Mandatory moisture protection to protect against condensation
    • Sufficient dimensions of the straight steam distribution section of the duct
    • correct design to eliminate possible places of permanent condensation
    • regular cleaning and disinfection of air ducts

    8. Direct spray systems (high pressure):

    • use only models with water treatment and disinfection, with automatic flushing of equipment and pipelines
    • providing a system with a permanent connection to electricity and water for automatic flushes

    9. Direct spray systems (compressed air):

    • use only models with pretreatment and water disinfection
    • At the end of each humidification phase, the system must run an empty cycle through the spray nozzles by blowing out only compressed air to completely dry all parts
    • ensure that the system is always connected to power and water, even if there is no demand for humidification.

    To make any humidification system even safer, all sprayed water must come from a drinking water source that is bacteriologically pure.

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    Reviews about the company

    Rating 5 out of 5

    I was very pleased with the work of the manager. He answered all questions immediately, was always in touch, came to the apartment with engineers, controlled all processes. He suggested a solution that I would not have thought of myself. The installers are also great, they put everything in quickly, they didn’t scratch anything anywhere in the house, although they put it in ready repair. And they cleaned up after themselves so that you can’t find fault. The installation has been running for six months, no comments. The air is really fresh. I recommend.


    Rating 5 out of 5

    We are satisfied with the choice of humidification system and the work of specialists. At the first contact, the manager immediately asked clarifying questions, then in the showroom he showed and told how everything works. He consulted over the phone and answered questions in detail. The installers installed the equipment in three days, and cleaned up after themselves, which was especially pleasing. They launched and configured the system in our presence, showed how to manage the settings. Four months have already passed – the equipment works like clockwork. Happy to recommend this company.

    Nikolai and Marina G.

    Rating 5 out of 5

    I recommend the company “Humidification Systems”. The main thing that I liked was the solid equipment, thought out to every screw. Intelligent engineers who know their stuff. Polite and attentive managers – they know how to find an approach to everyone, understand what the client needs, and not just sell anyhow. From the first call to the installation itself, the manager was in constant contact, answered all questions, advised, and controlled the process. In general, the company is the people who work in it, to be sure.

    M.V. Egorov

    Estimated 5 out of 5

    Two years ago we moved to a new high-rise apartment. Almost immediately we noticed that the air is very dry and the humidifier does not cope with its task at 120 squares. We visited several companies and eventually chose “Humidification Systems”. I must say, they were not mistaken – the impressions are the best. In the showroom, they looked at and chose the equipment, then we quickly calculated the estimate, and work began a week later. In a few days, the installers installed everything, even the walls did not have to be ditched. As a result, there are no bulky structures in the apartment now, all nozzles are under the ceiling. The equipment is all hidden in the laundry room, so you don’t trip over it. Everyone is happy, thank you!

    Vadim A.

    Rating 5 out of 5

    This is not the first time I have contacted the Humidification Systems company. Two years ago I ordered a humidifier from them for my apartment. Then there were many doubts, questions, experiences. But managers and engineers explained everything, patiently told and showed the equipment.