Cooling Tower Operation Tips During Heat Waves
The NYC Department of Health and Mental Hygiene (DOHMH) recently issued a checklist of cooling tower operating tips during heat waves. According to the notice, hot and humid weather that may cause disruptions from elevated condenser water temperatures, microbiological fouling, and rapid Legionella growth. As air temperatures peak, condenser water temperatures rise, hours of operation increase, evaporation loss soars, and efficiency diminishes, the DOHMH says the benefits of preventive maintenance and routine upkeep are most important.
The tips below are in addition to the required annual hyperhalogenation requirements to be performed between July 1 and Aug. 31. This summertime hyperhalogenation is an additional preventive maintenance requirement aimed at reducing the risk of Legionella growth in cooling tower systems during the summer months, when Legionella and other bacteria can multiply very quickly.
To help owners remember the best practices during heat waves, DOHMH has come up with the acronym “A few TIPS.” DOHMH says you don’t need to be an expert on every technical detail to manage the increased risks associated with these challenges but recommends owners and managers go over the checklist below with the building’s water management team.
A few TIPS Checklist
ANTICIPATE: Keep an eye on the weather. Be prepared for hot weather in the forecast.
o Actively monitor weather forecasts
o Enlist your water management team including facility personnel (responsible person), water treatment vendor, and mechanical contractor to carry out this checklist
TREAT: Monitor water quality [24 RCNY 8-05(f)].
o Adjust biocide dose in anticipation of faster depletion of residuals during hot weather
o Adapt biocide dosing for increases in water volume and demand when backup pumps, chillers, and cooling tower cells come online during peak usage
o Perform more frequent manual checks of biocide residuals during extreme weather
o Check inventory of treatment chemicals and schedule delivery with your water treatment vendor
o Check chemical feeds are working as scheduled and that there are no missed doses
o Regularly review local and remote monitoring records. Variation from target ranges may indicate malfunction or the need for feed rate adjustment
o Diligently maintain chemical application logs and records
INSPECT: Make sure the Cooling Tower System (CTS) and its mechanical equipment are ready. Have your facility personnel or mechanical contractor inspect your equipment [24RCNY8-04(a); 24 RCNY 8-04(c)(1)].
o Check circulating pump function and clean strainers
o Monitor condenser water temperatures and cycles of concentration
o Check spray system distribution and correct clogged or broken nozzles
o Check drift eliminators and fill for damage or short-circuiting of water or air
o Check the fan’s blades, cylinder, hub, bolts, belt, and speed
o Check makeup water supply and level controls
o Inspect tower for leaks, splashes, or blockages that obstruct water flow
o Confirm accessible CTS wetted surfaces are free of contaminants, deposits, biofilm, algae, and corrosion
o Confirm bleed monitor is calibrated and operating properly and that bleed capacity is sufficient
o Maintain clean heat exchange surfaces (condensers, plate heat exchangers, etc.)
o Check operational efficiency of heat exchangers and chillers and schedule servicing or cleaning, if needed
PROTECT: Enhance your diligence to reduce risks.
o Diligently identify issues, report them to the water management team. Investigate any system anomalies or changes and adjust water treatment immediately
o Perform summertime hyperhalogenation between July 1 and Aug. 31 and collect required Legionella sample
o Consider an additional or larger dose of biocide during periods of extreme weather
o Perform additional bacteriological testing (e.g., dip slides and/or Legionella testing) to validate treatment
SAVE: Reduce cost and impact of your CTS.
o Decrease heat load and energy use by raising thermostat setpoints and reducing cooling in areas not in use
o Reduce hours of cooling system operation when possible
o Review setpoints and triggers for any automated operations of your cooling tower system