For high-rise commercial complexes, data centers, and heavy industrial processing plants
throughout the Greater Toronto Area (GTA), cooling towers are the unsung heroes of summer
thermal management. These systems provide the critical heat rejection necessary to keep
massive water-cooled chiller plants running at peak efficiency. However, as outdoor ambient
temperatures climb and evaporation rates spike in June, a cooling tower’s open, wet
environment becomes highly vulnerable to severe operational and biological risks.
Without an aggressive, data-driven water treatment and mechanical maintenance strategy,
summer operational conditions will rapidly trigger two major interconnected threats: mineral
scaling and biological fouling.
Left unmanaged, these issues do not just destroy your system’s heat transfer efficiency and
spike your electrical bills—they can also expose your organization to immense regulatory and
legal liabilities.
The Chemistry of Summer Scaling
A cooling tower rejects heat through the process of latent heat of vaporization—meaning it
intentionally evaporates a portion of its circulating water loop to cool the remaining water.
However, while pure water vapors escape into the atmosphere, the dissolved solids, minerals,
and calcium carbonates present in the makeup water stay behind inside the basin.
As this evaporation cycle continues relentlessly during hot June days, the concentration of these
minerals climbs rapidly. This relationship is measured as the Cycles of Concentration (CoC):
$$\text{Cycles of Concentration (CoC)} = \frac{\text{Chloride Concentration in Tower
Water}}{\text{Chloride Concentration in Makeup Water}}$$
If your CoC is allowed to climb too high without a controlled blowdown (bleeding off mineral-
heavy water and replacing it with fresh water), the water becomes supersaturated. Minerals will
precipitate out of solution, binding directly to the internal fill pack and the chiller’s condenser
tubes as a hard, insulating crust known as scale.
Because calcium scale has an incredibly low thermal conductivity, a layer of scale thinner than a
business card can decrease your heat exchange efficiency by greater than 10%, forcing your
chiller compressors to draw excessive power to meet your facility’s cooling demand.
3 Critical Biological Risks in Warm Water Loops
While scaling hampers mechanical efficiency, the combination of warm water (typically between
$20^\circ\text{C}$ and $50^\circ\text{C}$), constant sunlight exposure, and scrubbed organic
debris from the air creates a perfect incubation chamber for biological growth.
Microbiologically Influenced Corrosion (MIC)
Algae and anaerobic bacteria form dense, sticky slime layers called biofilms along the metallic
surfaces of your cooling loop. Beneath these biofilms, specific bacteria species produce
localized acids that aggressively eat through carbon steel and stainless steel pipe walls. This
process, known as Microbiologically Influenced Corrosion (MIC), can cause sudden, pinhole
pipe leaks and premature structural failure of the tower basin.
Microscopic Air Scrubbing and Silt Accumulation
Cooling towers act like massive air washers, drawing thousands of cubic feet of ambient air
through the water spray every minute. In industrial zones and logistics corridors around Toronto,
this air is filled with dust, pollen, and airborne particulate matter. This organic debris settles into
the cooling tower basin, forming a thick layer of nutrient-rich silt that feeds biological colonies
and chokes water flow.
The Threat of Legionella Proliferation
The most critical biological risk in any open evaporative cooling system is Legionella
pneumophila, the bacterium responsible for Legionnaires’ disease. When a cooling tower
operates, it naturally creates a fine mist of water droplets called drift. If the tower’s water loop is
heavily fouled with bacteria, these microscopic drift droplets can carry Legionella miles away on
wind currents, risking inhalation by building occupants or the general public.
Operational Best Practices for June Protection
To defend your facility against both structural scale and biological pathogens this summer, your
engineering team must integrate precise chemical water treatment with targeted mechanical
safeguards.
Calibrated Biocide Dosing Schedules
Static, automated chemical timers are rarely sufficient to handle changing summer weather
loads. Work closely with your water treatment partner to implement a dual, alternating biocide
program. Alternating between an oxidizing biocide (like chlorine or bromine) to rapidly rip apart
organic biofilms and a non-oxidizing biocide to penetrate deep into resilient bacterial cell walls
prevents pathogens from developing chemical resistance.
Automated Blowdown and Total Dissolved Solids ($TDS$) Control
Replace manual, guesswork-based water draining with automated conductivity controllers.
These systems continuously monitor the Total Dissolved Solids ($TDS$) within the circulating
water loop. When mineral concentrations cross a strict technical threshold, the controller
automatically opens the blowdown valve, discharging a precise amount of concentrated water
while introducing fresh makeup water to lower scaling potential safely.
[ TDS Sensor Detects Mineral Spike ] ──> [ BAS Opens Blowdown Valve ] ──> [ High-Mineral
Water Discharged ] ──> [ Fresh Makeup Water Restores Balance ]
Drift Eliminator Inspections and Mechanical Cleaning
The physical line of defense against biological drift transmission is the tower’s drift eliminator
network. These nested, baffled panels are designed to capture escaping water droplets and
redirect them back down into the basin while allowing hot air to vent.
● The Action Item: Inspect drift eliminators for warping, gaps, or brittle scale buildup that
could allow untreated water droplets to escape. Combine this with regular physical basin
cleanings and high-efficiency side-stream sand filtration to systematically strip out
Maintain Efficiency and Bio-Safety Compliance This
Summer
A fouled, scaling cooling tower is a severe threat to your facility’s energy budget, system
longevity, and corporate liability. By executing a rigorous water treatment regimen, tracking your
cycles of concentration, and maintaining absolute biocide control, your cooling plant will operate
safely, reliably, and at peak thermodynamic efficiency through the hot summer months.
Is your cooling tower loop mechanically prepared and chemically balanced for the June
peak heat? Contact AirTrack HVAC’s commercial maintenance team today to schedule an
intensive cooling tower performance audit, water analysis, and optimization service.
