Delta TM-105312 manual Cold Weather Operation, Cold Weather Protection, Separate Indoor Sump

Cold Weather Operation

Cold Weather Protection

The cooling tower may require protection against freezing at light heat loads when the wet-bulb temperature is under 32°F., or during shutdown when the temperature drops below 32°F.

The following methods are recommended for use in Delta Cooling towers for protection during cold weather conditions. Recommended equipment is optional and may be ordered from the factory. Consult the factory for further information on which equipment to choose for your specific application.

Separate Indoor Sump

This method is virtually a foolproof antifreeze protection system with the added advantage of minimum maintenance. The indoor sump tank should be large enough to fill the entire recirculation system without danger of pump cavitation. As a general rule, the tank should be sized to hold three times the rate of circulation in gallons per minute (gpm).

The tank should be provided with properly sized overflow, make-up drain and suction connections. When a separate sump is ordered with a cooling tower, the water make-up valve assembly and the overflow and drain connections are installed in the indoor sump only.

When a sump tank is used, the cooling tower should be located high enough above it to allow free cold water gravity drain. A bottom outlet can be provided for gravity drain to indoor sump tank installations.

Reverse siphoning is a back flow of non-potable, recirculating water into a potable water system, which can occur through the make-up float valve assembly located in the water reservoir. Should the valve malfunction, blockage of the overflow or outlet lines would cause water level to rise in the reservoir, and the make-up water pressure could drop below the atmospheric pressure creating a vacuum at the make-up inlet. Although precautions to prevent reverse siphoning are incorporated in the cooling tower design, we also recommend installing a check valve in the water make-up supply line, as a backup precaution.

Electric Immersion Heater

Cooling towers can be ordered with an anti-freeze immersion heater systems, which consist of a 6KW heating element, water level sensor, adjustable thermostat and contactor. Components are factory installed, but will require field wiring.

Thermostatic On/Off Control

A thermostatically controlled fan for on/off operation, should be considered as an energy saving feature, for capacity control during winter operation. The thermostatic control can be field set to insure automatic fan shut-down when cold water drops below design temperatures, as well as fan start-up when cold water rises to design temperature.

A thermostatic control provides excellent cooling tower anti-freeze protection while reducing operating costs throughout cold weather operation.

Revised 1-8-2007 14