Steam Humidification—Where to Use What

We recently shared a brief overview of the most common forms of steam humidification for industrial and commercial applications and how the technologies work. While understanding the technologies behind these models is an excellent basis to build from, knowing how something works does not reveal why it might be a good choice in your specific use case.

Find our guide below to discern which form of steam humidification is fit for your purpose.

Electrode Steam Humidification

This form of steam humidification harnesses the conductive water impurities, passing an electric current between submerged electrodes to create steam.

Positives:

• Low unit cost- Electrode humidifiers tend to cost less per unit than similarly sized models using a different technology. This is often compared against the lower consumables required of a similarly sized resistive unit.
• Reliability- Units of this style can achieve humidity control by regulating the flow of fresh and drain water and strength of the electrode’s current. A typical unit can reliably achieve ±5/10%RH with stable temperature.
• Effective- These units require power, mains water and a drain, making them simple to install and allowing the units to be deployed almost anywhere in a building.
• Agile- As steam is produced by the amount of electrical current being passed between the electrodes, changing and altering the amount of steam humidification provided is fast and effective.
• Simple- Electrode models are easy to troubleshoot and repair with good accessibility for working on the units in the field.
• User friendly- Electrode humidifier units tend to use a touch-screen display, allowing easy control for end users and easy access for maintenance  

Negatives:

• High water usage- In order to regulate and control the amount of ions present, and thus the amount of steam produced by the unit, this style of humidifier requires regular drain cycles, which requires a pause in activation.
• Higher operational cost- Scale build up from the heated and electrified ions can reduce unit efficiency. At worst it can prevent unit operation entirely, until a new boiling chamber can be installed.
• Regular maintenance required- While scale can be removed with cleanable cylinders, eventually electrode steam humidifiers suffer a degradation of the electrode, becoming degraded and worn. This prevents the model from operating at its highest efficiency. The presence of an electrical current in the evaporation cylinder means it has to made of plastic or another non-conductive material reducing cylinder life compared to resistive stainless steel cylinders.

Ideal applications:

• Cleanrooms
• Manufacturing Facilities
• Pharmaceutical Production
• Hospital/MRI Rooms
• Archives, museums and theatres

These steam humidification units use a submerged heating element, heating the surrounding water and producing steam.

Positives:

• Lower running costs- When combined with a Reverse Osmosis water treatment unit resistive these units do not require regular draining or ion regulation, so use less water in day to day running than their electrode counterparts. This process reduces the humidifiers water consumption and means a constant rate of steam production is possible.
• Multiple sizes- As one of the more popular technologies in the humidity control market, this style of steam humidification unit is available in multiple sizes.
• Precise control- As this unit controls steam generation through a single factor – the heating element – it is capable of more accurate humidity control, typically achieving and holding conditions at ±2 – 5%RH at a stable temperature.

Negatives:

• Maintenance demanding- While these units will work in hard water areas, the presence of ions and minerals in the water supply allows for unwanted and avoidable scale build-up, which lowers the unit’s effectiveness and can shorten it’s usable life span or increase the maintenance frequency.
• More expensive per unit- While there is a return in investment over time, resistive units tend to be more expensive at the point of purchase.

Ideal applications:

• Cleanrooms
• Manufacturing Facilities
• Pharmaceutical Production
• Hospital/MRI Rooms
• Archives, museums and theatres

Steam-to-steam Humidification

Steam-to-steam humidification harnesses steam from a centralized network which, for hygiene or technical reasons, cannot be used directly. The steam from the centralized system is fed through a submerged coil, allowing heat energy to transfer to the fresh water and create sterile steam. This can also be called steam transferal.

Positives:

• Lower cost- Steam-to-steam humidification makes use of an in-place system, building on and improving what already exist.
• Exceptionally low energy- As high temperature steam is already present in the centralized system, this unit does not have to expend as much energy to raise water to the correct temperature.
• Cost benefits- especially for large systems

Negatives:

• Resource reliant- Steam-to-steam humidification requires a centralised Direct Steam system to already be in place in order to be effective.
• Prohibitive costs- Building a boiler and constructing piping through a building is vastly more expensive than an application specific unit.
• Slow control response- Due to the more complicated method of steam production, this style of humidification tends to be less agile than counterparts

Ideal applications:

• Airports
• Hospitals
• Museums and galleries
• Universities
• Buildings with centralized live steam which require climate control

Gas Steam Humidification

Gas-fired steam humidification works in a similar method to it’s electrode and resistive counterparts, but uses a combustion chamber and heat exchanger rather than electricity to heat water.

Positives:

• Lower cost- Gas, or fuel fired, humidifiers are typically less expensive operate than an electric unit.
• Agile- This form of steam humidification can respond swiftly to changes in demand.
• Huge output range- Gas humidifiers are sized to produce up to 400 kg/hr of steam making them ideal for large humidifier duties

Negatives:

• Gas as a primary resource- Little opportunity to use green energy.
• Combustible resource- Should an accident occur within the system it would require an engineer specifically trained in gas systems and additional safety procedures.
• Limited- Gas fired steam humidification works best. Applications where large duties are required. They are not good at providing close control at the bottom end of their output range and will sometimes require a small additional electric steam humidifier to provide this control.

Ideal applications:

• Hospitals
• Healthcare
• Spray booths
• Clean rooms
• Laboratories

Direct/Live Steam Humidification

Direct, or Live, steam humidification relies on a boiler being elsewhere in a building. The steam produced in the boiler is then piped around the building. Direct steam humidification takes this steam and disperses it directly into the controlled environment or an air handling unit.

Positives:

• Energy efficient- As the boiler and piping already exists, direct steam humidification simply uses what is already there, driving down costs.
• Very low buy in- Because there is no need for a separate unit to produce steam, the initial cost of a unit is very low.
• Lack of waste- Many models of this type do not drain away water. Condensate is instead returned to the steam source, allowing heightened water usage efficiency in this application.

Negatives:

• Reliant on other systems- If there is a fault in the boiler, or in the piping, this will have a knock-on effect on the steam injection.
• Requires filtering- Travelling for a long distances, even through insulated pipes, can cause steam to condensate. To ensure dry mist dispersal the steam feed has to be filtered ahead of dispersal into the controlled environment.

Ideal applications: