Forced draft cooling tower installations are becoming increasingly more popular. Cooling tower technology allows for a fan to be mounted on the top or bottom of a cooling tower. Cooling towers with top mounted fans are called “induced draft” cooling towers and cooling towers with bottom mounted fans are called “forced draft” cooling towers.
Forced Draft Cooling Tower
Induced draft cooling towers frequently employ a fan, coupling, gear box, drive shaft and motor at the top of the cooling tower. This equipment is used to induce air from the bottom air inlet louvers up through the fill media. This location accelerates wear and tear of the equipment because it is exposed to the elements (sun, rain, snow, etc.), and is positioned in the hot, corrosive exhaust airstream. This makes the mechanical equipment difficult, expensive, time-intensive and dangerous to maintain.
Forced draft cooling towers have the mechanical equipment at the bottom of the tower. This location allows the equipment to operate in the cool, dry intake airstream protected from the elements. This location makes the equipment accessible from ground level so it is easy, inexpensive, less time consuming and much safer to repair while enjoying substantially increased life expectancy of the mechanical equipment.
Cooling tower Legionella is an ever increasing concern, especially in many HVAC scenarios such as hospital cooling towers, university cooling towers, and other like applications where the cooling tower exists among a large population. There are six events that must ensue in order for a Legionellosis case to occur: (1) An environmental reservoir must exist; (2) multiplication to high cell counts must occur; (3) there must be a mechanism to disseminate bacteria; (4) the disseminated strain must be virulent; (5) infection must occur at susceptible site on a host; and (6) the host must be susceptible.
Being reservoirs of water and dust, all cooling towers can potentially harbor Legionella sp. bacteria thereby satisfying event (1). Events (4) through (6) are beyond the control of cooling tower manufacturers and operators. Thus we have events (2) and (3) in which to exert a protective influence. The environmentally friendly and operator friendly design of the Tower Tech Modular Cooling Tower™, especially when combined with a judiciously administered and monitored biocidal treatment regimen, effectively addresses events (2) and (3).
Learn more about how to avoid cooling tower Legionella by visiting our white paper: http://www.towertechinc.com/documents/Legionella_Control_White_Paper_05072004.pdf
FRP cooling tower structures have become increasingly more popular over the past 20 years. Historically, galvanized metal for small to mid-sized applications and wood for mid to large-sized applications had the dominant role in cooling tower structures. Due to environmental, aesthetic, dependability and life expectancy concerns, many users have turned to alternate materials of cooling tower construction such as FRP.
FRP Cooling Tower
Galvanized metal and wood structures have posed serious environmental concerns due to the harmful chemicals that can leech out into the cooling tower blow down. The corrosive nature of the materials can become unsightly, require maintenance and repair, and result in reduced life expectancy of the cooling tower.
FRP cooling tower structures are not corrosive and therefore improve environmental friendliness and aesthetics while significantly improving life expectancy with little to no maintenance required. FRP cooling towers include hand laid up, injection molded and pultruded methods of construction. Hand laid up is less popular due to the difficulty of getting consistent fiber distribution, which can result in fiber bloom and degradation concerns. Injection molded FRP is popular for keeping a low price with smaller HVAC applications. Pultruded FRP is the material of choice for mid and large size applications due to the structural integrity of the structure.
Most pultruded FPR cooling towers will have an initial investment 30% greater than that of galvanized metal or wood. However, the benefits to the environment, lack of required maintenance, improved aesthetics and dependability, and significantly improved life expectancy offer a solid ROI.