6-12
October 2012
tower make-up with little or no pre-treatment, including air handler condensate (i.e.,
water that collects when warm, moist air passes over the cooling coils in air handling
units). This reuse is particularly appropriate because the condensate has a low min-
eral content and is generated in greatest quantities when cooling tower loads are the
highest. For additional sources of water that could be used as cooling tower make-up
water, refer to
Section 8: Onsite Alternative Water Sources
.
Operation, Maintenance, and User Education
For optimum cooling tower efficiency, there are a number of operations, mainte-
nance, and user education strategies to consider, such as maintaining system energy
efficiency, monitoring the cooling tower’s water chemistry and flow, choosing a
water treatment vendor, maximizing cycles of concentration in the tower, and paying
close attention to water chemistry reports.
Maintaining System Energy Efficiency
To maintain the system energy efficiency, consider the following:
••
Implement energy-efficiency measures to reduce the heat load to the tower.
As the heat load is reduced, cooling tower water use will be commensurately
reduced.
••
Implement a comprehensive air handler coil maintenance program. Dirty coils
can increase the load on the chilled water system used to maintain building tem-
peratures. Increased load on the chilled water system will increase the load on
the evaporative cooling process, requiring more make-up water for the cooling
tower.
••
Properly maintain and clean heat exchangers, condensers, and evaporator coils
to prevent scale, biological growth, and sediment from building up in the tubes.
••
Properly insulate all piping. Insulate chillers and storage tanks, if installed.
••
When cooling specific equipment using the cooling tower water loop or chilled
water system, use the minimum flow rate required to cool the system recom-
mended by the manufacturer. In addition, regularly check operation of the water
control valve so that cooling water only flows when there is a heat load that
needs to be removed.
Monitoring the Cooling Tower’sWater Chemistry and Flow
Monitor the cooling tower’s water chemistry and flow by considering the following:
••
If available, have operations and maintenance personnel read the conductivity
meter and the make-up and blowdown flow meters regularly to quickly identify
problems and determine when to make adjustments.
••
Keep a detailed log of make-up and blowdown quantities, conductivity, and
cycles of concentration and monitor trends to spot deterioration in performance.
6.3
Cooling Towers
