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Museums and art galleries should be kept at stable temperature and humidity levels to prevent damage to priceless artifacts .
right questions to ask when projects involving humidifiers don ’ t occur that frequently in an HVAC consultant ’ s career .
Buxton offers the following answers to some frequently asked questions :
What level of humidity is required and what level of fluctuation is acceptable ? Different applications will require various levels of humidity control . The most common application for an HVAC consultant will be the office environment ’ s requirement of between 40-60 % RH , whereby people are comfortable and static build-up is reduced . Many manufacturing industries will require a more specific level of humidity control : 50-60 % RH for printing ; 65-75 % RH for textile manufacture ; or 45-55 % RH for an ideal museum environment .
How long will the humidifier be running for and when can it be shut down ? If a humidification system is going to be used 24 / 7 then the number and type of humidifiers will need to reflect this . A critical system that needs to be constantly delivering a certain level of humidity must include run and standby humidifiers as every humidifier in the world needs to be shut down occasionally for maintenance .
How important are running costs and the environmental impact of the system ? Running costs vary widely with different types of humidifiers . Some steam systems can use 150 times more energy than an efficient evaporative humidifier and require six times more to be spent on them
Federico Scarionati / Unsplash in servicing and spare parts . The initial purchase cost is a lot less for the steam system but an error in the initial product selection can cost the client ( and the environment ) dearly over the life of the unit .
What types and how much energy is available ? This is a critical question as it ’ s not unheard of for contractors to arrive on site to install equipment only to find out that the amount of electricity required to run a humidification system is not available . For really large duties , the energy requirements of using an electrical system can become prohibitive and either evaporative , spray or gas humidifiers may be a more viable option for the end-user .
What quality water is being used and what level of maintenance is acceptable ? Water quality and maintenance are intrinsically linked when dealing with humidifiers as a poor water quality inevitably leads to a higher servicing requirement . The minerals left behind in the humidifier when the water is either boiled or evaporated into an atmosphere need to be dealt with . If the water has a high mineral content but a high level of maintenance is unacceptable , water treatment should also be specified .
What evaporation distance is required ? For humidifiers providing moisture to ducts or AHU systems , the humidifier must be able to evaporate the moisture into the air stream before it meets physical obstructions , like duct corners , otherwise this will cause condensation .
Where are the humidifiers to be situated ? If access to the location is restrictive , certain humidifiers may be easier to install than others . Also , if a unit is located in an awkward position , then servicing may be difficult or sometimes impossible .
THE CORRECT LEVEL OF HUMIDITY IN AN INDOOR ENVIRONMENT Humidity conditions can vary sharply according to location — not only inland or coastal factors but differing regional weather cycles — thereby challenging the engineer to implement the correct affordable solution in terms of capital cost and energy consumption . This could include extremes such as permanent high humidity levels because of continual rain , or low levels due to habitats where RH can be as low as a couple of percent such as in the Karoo .
With this constant change in ambient condition it is critical to accurately control relative humidity in many different applications . Many humidifier users work with “ Hygroscopic ” materials . This means that a material can lose moisture to the air in dry conditions or absorb moisture
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RACA Journal I March 2023 www . refrigerationandaircon . co . za