Feature
HUMIDIFIERS DEMISTIFIED
By Eamonn Ryan
With a wide range of humidifiers on the market and an increased requirement by end users to reduce energy costs and CO 2 emissions , RACA Journal looks at the pros and cons of the different types of humidification systems available today .
Without food , a person can live for five to 10 days .
Without water they can carry on for two to three days . Without air they die in three minutes . Until recently , we never had to fear for our precious air , of which we consume copious amounts — between 300l and 600l every hour .
Today , the quality of the air we consume is of senior importance , and something which controls that quality and comfort is its relative humidity ( RH ) level . Humidity is essentially the percentage of water as a vapour in any given space . A common analogy is the concept of a cubed sponge that would be proportionately saturated based on the ideal gas law factors . The ‘ ideal gas ’ law describes the relationship between pressure , volume and temperature in air .
At a specific temperature of 25 ° Celsius in summer , that sponge could be 60 % full , while at 25 ° C in winter it could be 30 % full . As contraction and expansion of air occurs , the volume either gets smaller or increases . As RH increases it will eventually reach saturation known as the dew point — the air has cooled down to the point where the water inside the air is at 100 %. It has got nowhere else to go and so results in condensation .
Duncan Buxton , marketing manager , Condair , offers the following suggestions as to the diverse types of humidification systems .
STEAM The traditional type of humidifier installed by AC contractors is the electrode boiler humidifier . The unit creates steam by passing current through water inside a replaceable or cleanable plastic cylinder . They can be used with steam lances to humidify ducts or fan units to directly humidify a room ’ s atmosphere . An electrode boiler humidifier has a low capital cost and is simple to install making it a favourite among contractors . However , it does have the highest running cost of any humidifier , making it less popular with end-users .
As steam is produced in an electrode boiler , any minerals in the water are deposited within the plastic cylinder as limescale . Periodically these cylinders require replacement , which is a
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straightforward operation . However , for high duty applications the spares and service costs associated with maintenance in a year can be more than the initial purchase price .
In recent years there has been a trend to move away from the electrode boiler to resistive steam humidifiers as they do not require replaceable boiling cylinders and therefore have lower running costs . The capital cost is higher , but this is quickly paid back in reduced spares and servicing expense . Some resistive systems , such as the Condair RS , have innovative scale management features which allow limescale to be removed quickly and easily without needing to open the main body of the humidifier .
Like the electrode boiler , the resistive humidifier is simple to install and can be used to humidify directly in a room ’ s
Humidity is critical to the precise functioning of laboratories .
Christiaan Schalekamp , Technical Sales Director at Humidair .
www . refrigerationandaircon . co . za RACA Journal I March 2023 23