1- Laws of physic are ruthless




Tap water we consume is never 100% pure:  it contains other natural elements (or not) such as minerals or metals or other chemical compounds.

Whatever the humidification method, it is necessary to take care of these elements contained in the water.

Water pre-treatment such as water filters, Reverse Osmosis (RO) membranes or Deionization (DI) beds will reduce most or eliminate all of the particulates.

Water pre-treatment is mandatory for adiabatic humidification by water atomization, otherwise all the particulates contained in water will be sprayed in the air , this will result in dust deposit and risk of distributing other contaminant in the air.

When water is evaporated by means of an evaporation media or for isotherm humidification when steam is produced from boiling water, the water  pre-treatment is not anymore mandatory, as steam is pure (pure H2O in the form of vapor), in those cases you need to deal with those water dissolved solids (TDS) afterwards, as those one will precipitate in a form of scale that can be as hard as a rock.

Another ruthless law of physic is the amount of energy to increase relative humidity of surrounding air that is the same whatever the method of humidification is: It is the amount energy to change H2O from liquid to vapor. 970Btu are required to evaporate 1lb [0.45kg] of water at sea level.

Adiabatic process will take this energy from surrounding air, so water evaporation will also result in cooling the air. Isothermal process will take this 970Btu per pound of water from other source such as electricity or gas to boil water and produce hot  (saturated) steam.



2 – Water evaporation with steam


As mentioned above water pre-treatment is not mandatory for steam humidification. Steam humidification has many advantages:

  • No contaminant contained in the liquid form of tap water is transferred to vapor phase (steam)
  • Steam is pure and sterile
  • Steam is hot, with a temperature of 212F (100°C), it will kill any surrounded contaminant
  • Steam is naturally and quickly absorbed to the air at any temperature.
  • Steam production can easily be adjusted to RH% demand by reducing or increasing energy input and boiling rate.


Water is boiled from water tank called steam cylinder, or steam chamber, or evaporation chamber. There will be heating elements or electrodes rods or heat exchanger immersed in the water. This tank will need to be open and cleaned if in stainless steel or to be replaced if in plastic.







3 -Foaming

Another effect of producing steam by boiling tap (untreated) water is the possible foaming of during water boiling.

Anybody that has cooked some pasta for dinner has experienced water boiling and foaming. In the case of cooking pasta the foam is due to the input of starch from the pasta which are added to boiling water.

When foaming is occurring it is sudden, it is strong enough to be able to sometime lift the cover of the pot, and it will result in overflowing water.

In the case of the steam humidifier, the constant production of pure steam which does not contain TDS will cause the concentration of TDS in the water in the cylinder to increase, to a certain extent and depending on the exact nature of these TDS, conditions for the foam to arise are satisfied. The water concentration is too high.

For this reason, any steam humidifier will be equipped with a foam detection sensor. This foam sensor is usually made from one or more conductive probes placed on top of the steam cylinder. Foam is always conductive. As soon as detected boiling should stop and TDS concentration in the water needs to be decreased before to start over the steam production. In other words, you need to flush this dirty water and replace it.



4 – How to avoid foaming?


There are three methods to de-concentrate the TDS from boiling water in steam chamber.



Skimmer is a simple and efficient method, the water reservoir is designed so that every time you re-fill it with new water, some of the water from the top of the tank will overflow and be evacuated to drain. TDS concentration from the top layer of the water is reduced, risk of foaming to occurred is reduced.

There are two important problems with this methods:

1) Overflowing boiling water is very costly energy wise. Humidifier will constantly waste water and steam during steam production.

2) Adjusting the skimmer overflow rate is not easy because it depends on the mechanical and hydraulic construction of the evaporation chamber.

Drain frequency

Drain frequency sometime called flush cycle, does consist in replacing part or full water content from the steam cylinder, water content is drained down at regular and fixed time intervals.

Those time intervals are sometime calculated based on the true evaporation rate of the humidifier but not always, some steam humidifier drain frequency is independent from evaporation rate, full or part of cylinder content is wasted to drain. Water is renew with new and cold water. As soon as cylinder is full again the steam production can resume.

Drain frequency is adjusted depending on water TDS measurement during first start-up or based on technician or building owner experience.

Again the energy wasted by draining hot water is very important. Also there will be a drop in RH% in the humidified space during the water replacement process.

Water dilution

Water dilution sequence have been developed primarily to avoid drop in steam production caused by the drain frequency method.

This method consists in draining small amount and adding same small amount of fresh water at smaller time intervals. When properly set there will be no more drop of RH% in the humidified space.

Water dilution parameters are numerous, amount of water drained, time interval, power input during water filling, amount of water brought in… As for any of the foam prevention method settings are based on water quality (amount of TDS contained in water).

Main problem of this method is the complexity in setting it up properly and efficiently for the steam humidifier.


5 – What is EcoEnerSmart ™ function?

EcoEnerSmart ™ is totally unique in the industry, it is a water dilution system that is set automatically and will automatically adapt to the actual water conditions during the life of the steam humidifier.

EcoEnerSmart ™ function is patented. It is the result of the rich experience of steamOvap design team. It is possible thanks to the use of incomparable calculation power of board computer used in our humidifiers and to the full extent of real time clock operating system.


As soon as the technician is selecting Autodilution the steam humidifier will select the water dilution sequence settings developed for this specific model. As indicated above, water dilution sequence settings does include time intervals, amount of water drained, amount of new water filled, energy power management to ensure constant steam production. In the event that foam would occur, this event is recorded and settings of water dilution sequence are automatically adapted in order to avoid any further foaming episodes.

Steam production is optimized, since drained water is reduced to minimum and water consumption is optimized as well.

Thus, there is no need for technical assistance to change the settings of the water dilution sequence, all you need to do is select ‘’Autodilution’’. There is no more need for an advanced degree in water chemistry or endless trial and errors to make a proper set up.


6. Savings with EcoEnerSmart ™





Hopefully EcoEnerSmart ™ function will help change minds. We have measured the energy and water saving to a standard 35 lb/h electric steam humidifier, comparing EcoEnerSmart ™ function to a drain frequency (full tank flush at fixed intervals) method over a period of 24 hours.

Your will save 18.3kWh and 97 Gallons of water (367 Liters) at the end of the 24h period.

A fair extrapolation for a full year operation period with a 50 % duty cycle will result in 3,300kWh of electricty power and 17,700 Gallons of water (67,002 Liters) !




Steam humidification is often pointed out as an energy-intensive humidification method.

As mentioned above in this article laws of physic are ruthless and watever the humidification method you select : 970Btu will be needed to evaporate one pound of water into the air.

With EcoEnerSmart ™, you can now save energy and water with your steamOvap steam humidifier. 

By preventing foam build-up, EcoEnerSmart ™ function makes life easier for its users. EcoEnerSmart ™ is totally unique in the industry, you do not need technical assistance to change the water dilution sequence, just select the “auto-dilution” mode and the work is done.

EcoEnerSmart ™ is a feature available on all our steam humidifiers, namely IER electric steam humidifier and ISE steam exchange humidifier .

Fighting COVID19 with humidification

Building humidification is critical for people’s health !

Maintaining relative humidity in offices, workplaces, schools or any other building reduces the potential risk of transmitting viral diseases.

Many scientific studies have confirmed that  an indoor relative humidity between 40%-60% will help fighting against viruses spread on 2 fronts:

  • Air with 40% to 60% RH will limit the spread and survival of any virus such as novel coronavirus SARS-CoV2.
  • a humidified air above 40% RH will help protect mucosal barriers of human beings , resulting in an increase resistance against any microbial attack.

Here are three of what we think as the most pertinent scientific studies related to the subject:

“Maintaining a relative humidity between 40%-60% within the building environement may help to limit the spread and survival of SARS-CoV-2 within the built environment, while minimizing the risk of mold growth, and maintaining hydrated and intact mucosal barriers of human occupants.” Read more

Abstract from “2019 Novel Coronavirus (COVID-19) Outbreak: A Review of the Current Literature and Built Environment (BE) Considerations to Reduce Transmission” by Leslie Dietz, Patrick F. Horve, David Coil, Mark Fretz, Kevin Van Den Wymelenberg, (2019)

“There are data to suggest that outdoor absolute humidity levels affect humidity levels inside and that simple humidifiers may be adequate to raise absolute humidity to levels associated with a significant reduction in influenza virus survival.” Read more

Abstract from “Influenza and humidity: Why a bit more damp may be good for you!” by Jane A. Metz, Adam Finn, (Journal of Infection (2015) 71, S54-S58)

“The relationship between inactivation and RH was not monotonic, and there was greater survival or a greater protective effect at low RH (20%) and high RH (80%) than at moderate RH (50%).” Read more

Abstract from “Effects of Air Temperature and Relative Humidity on Coronavirus Survival on Surfaces” by Lisa M. Casanova, Soyoung Jeon, William A. Rutala, David J. Weber, and Mark D. Sobsey, (2010)


SARS-CoV-2 is transmitted by aerosols


CDC (Centers for Disease Control and Prevention) and the WHO (World Health Organization) recognize that “pathogens that are primarily transmitted by close contact (i.e. contact and droplets) can sometimes also be transmitted by air in special circumstances”.

‘’The virus can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing or breathe heavily. These liquid particles are different sizes, ranging from larger ‘respiratory droplets’ to smaller ‘aerosols’. ‘’

Inadequate ventilation or air treatment allows an accumulation of small respiratory droplets and airborne particles that can remain viable and infectious in aerosols for hours.

The smaller the virus particle is, the longer the spread will be and the humidified air will act directly to stop the spread. This is explained in a study by Makoto Tsubokura, team leader for computational fluid dynamics at Kobe University and the RIKEN Institute. When the droplets come out of your mouth, they mix with the air and disperse. But when the air is dry, the droplets evaporate faster. As they evaporate, what we call aerosolization progresses. So, the droplets that would have fallen on the floor disperse more if the air is dry.

Maintaining air humidity between 40% and 60% indoors would allow a better fight against coronaviruses by reducing aerosol contamination.

How humidified air is helping us?

Above 30% relative humidity, human body’s defenses are stronger. Air that is too dry can be harmful to health due to dehydration.


Humidity is an essential condition for well-being :  Humidified air protects the human body and prevents dryness of the skin, eyes and lungs:


  • The skin is our first body barrier that needs to be hydrated to prevent itching, cracking and bleeding.
  • Tears protect our eyes from outside contaminants.
  • A dry nose, dry throat or dry lungs can increase the risk of respiratory infections.


Human body contains at least 65% water, humidified air is essential to maintain hydration, increase our immune defense and prevent health issues.

ASHRAE Epidemic Task Force



Dry air below 40% RH has been shown to:

    • Reduce healthy immune system function (respiratory epithelium, skin, etc.)
    • Increase transmission of some airborne viruses and droplets (COVID-19 still being studied)
    • Increase survival rate of pathogens
    • Decrease effectiveness of hand hygiene and surface cleaning because of surface recontamination or too-quick drying of disinfectants

Thanks to recent studies by ASHRAE, an international technical organization in the field of HVAC engineering, we have more information and new directions for HVAC systems to help mitigate SARS-CoV-2 transmission. 

More information


Isothermal or adiabatic humidification?

Air humidification is one of the essential Indoor Air Quality element to control in order to fight against SARS-CoV2 causing COVID19.  are the humidification methods equal? Is adiabatic humidification equal to isothermal humidification? Humidity is an essential condition for well-being : 

Isothermal humidification produces hot steam from boiling water. Energy to evaporate the water is introduced by a water heating source once the water has turned to hot steam it will be naturally a quickly absorbed by surrounding dry air with no more energy exchange.

With isothermal humidification, steam at 212F [100C] injected into the air will kill any pathogenic particles (bacteria or viruses) present.

It is pure, sterile and there is no additional risk of contamination from water; since, if any it would have been killed by heat-up water to the boiling point.

IER steam humidifier
IER steam humidifier

Adiabatic humidification is adding water to the air by using energy from surrounding air, fine droplet of water will evaporate to the air or  air will pass through wetted media. Since water evaporation is done by transfert of energy from surrounding air, the air is cooled as well as humidified.

Adiabatic humidification uses a source of cold water, which need to be free from contaminant before evaporation to the air. There are many strategies to reduce pathogenic particles from water itself, like filtration or purification such as Reverse osmosis filtration or deionization process, or with UV disinfection. 

Unfortunately, decontaminated or disinfected water evaporated into the air will not be able to eliminate pathogenic particles from the air, it will only pick them up and transport them further.

ACA atomizing humidifier
ACA atomizing humidifier

In conclusion, isothermal humidification using steam humidifiers is a better solution to fight against SARS-CoV2 causing COVID19 disease since the hot steam injected in the air is pure and sterile (free for any germ). This steam will kill any virus particles that would be in direct contact with the steam.          


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Featured Videos

If you want to learn more about SteamOvap and how humidification can benefit you, here are some videos on how to save energy with proper load calculation and how humidification can be helpful.