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Operation and Maintenance Instructions
Unit Piping
All external piping (water make up lines, equalizers, riser piping) that is not drained needs to be heat traced and insulated to make
certain it does not freeze. All piping should be fitted with drain valves to avoid dead legs which can also lead to Legionella
contamination. System piping accessories (make up valves, control valves, water circulation pumps and water level control
packages) also require heat tracing and insulation. If any of these items are not properly heat traced and insulated, the ensuing ice
formation may result in component failure and cause a shutdown of the cooling unit.
The use of a bypass should also be considered. Typically, winter loads are less than peak summer loads. When this is the case, a
cooling tower bypass needs to be incorporated into the system design to allow water to “bypass” the towerʼs water distribution
system as a means of capacity control. EVAPCO recommends that the cooling tower bypass be installed in the condenser water
piping system. Bypasses installed in this manner require a section of piping between the condenser water supply and return
leading to and from the cooling tower. Never use a partial bypass during cold weather operation. Reduced water flow can
result in uneven water flow over the heat transfer media (fill), which can cause ice formation.
Please note: bypasses should be periodically flushed to minimize stagnant water conditions, unless the bypass is piped directly
into the unitʼs cold water basin.
Unit Accessories
The appropriate accessories to prevent or minimize ice formation during cold weather operation are relatively simple and
inexpensive. These accessories include cold water basin heaters, the use of a remote sump, electric water level control and
vibration cut out switches. Each of these optional accessories ensure that the cooling tower will function properly during cold
weather operation.
Cold Water Basin Heaters
Optional basin heaters can be furnished with the cooling tower to prevent the water from freezing in the basin when the unit
is idle during low ambient conditions. The basin heaters are designed to maintain 40°F basin water temperature at a 0°F (or
-20°F & -40°F) ambient temperature. The heaters are only energized when the condenser water pumps are off and no water
is flowing over the tower. As long as there is a heat load and water is flowing over the tower, the heaters do not need to
operate. Other types of basin heaters to consider would include: hot water coils, steam coils or steam injectors.
Remote Sumps
A remote sump located in an indoor heated space is an excellent way to prevent freezing in the cold water basin during idle
or no load conditions because the basin and associated piping will drain by gravity whenever the circulating pump is idle.
EVAPCO can provide connections in the cold water basin to accommodate for remote sump installations.
Electric Water Level Control
Optional electric water level control packages can be furnished to replace the standard mechanical float and valve
assembly. The electric water level control eliminates the freezing problems experienced by the mechanical float. In addition,
it provides accurate control of the basin water level and does not require field adjustment even under varying load
conditions. Please note: the standpipe assembly, make up piping and solenoid valve must be heat traced and insulated to
prevent them from freezing.
Vibration Cut Out Switches
During severe cold weather conditions, ice can form on the fans of cooling towers causing excessive vibration. The optional
vibration switch shuts the fan off avoiding potential damage to or failure of the drive system.
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