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FREEZE PREVENTION <br /> When the ambient air temperature falls below 32°F, the Indoor Storage Tank <br /> water in a cooling tower can freeze. Marley Technical <br /> Report #H -003 "Operating Cooling Towers in Freezing With this type of system, water flows from an indoor tank, <br /> Weather" describes how to prevent freezing during opera- through the load system, and back to the tower, where it is <br /> tion. Ask your Marley sales representative fora copy. cooled. The cooled water flows by gravity from the tower to <br /> During shutdown, water collects in the cold water basin the tank located in a heated space. At shutdown, all <br /> and may freeze solid. You can revent freezin b addin exposed water drains into the tank, where it is safe from <br /> heat to the water left in the tower —or, you can rain the freezing. <br /> tower and all exposed pipework at shutdown. The table on page 21 lists typical drain -down capacities <br /> Electric Basin Heaters for all NC Series tower models. Although Marley does not <br /> produce tanks, many of our representatives offer tanks <br /> Marley offers an automatic basin water heater system, supplied by reputable manufacturers. <br /> consisting of the following components: The amount of water needed to successfully operate the <br /> Stainless steel electric immersion heater(s), system depends on the tower size and GPM and on the <br /> — Threaded couplings are provided in the side of the volume of water contained in the piping system to and from <br /> collection basin. the tower. You must select a tank large enough to contain <br /> NEMA 4 enclosure containing: those combined volumes —plus a level sufficient to main- <br /> — Magnetic contactor to energize heater. tain a flooded suction on your pump. Control makeup water <br /> — Transformer to convert power supply to 24 volts for according to the level where the tank stabilizes during <br /> control circuit. operation. <br /> —Solid state circuit board for temperature and low - <br /> water cutoff. <br /> Enclosure may be mounted on the side of the tower. <br /> Control probe in the collection basin to monitor <br /> water temperature and level. <br /> Heater components are normally shipped separately for <br /> installation by others. When purchased in conjunction with <br /> the Marley Control System option, they are factory installed <br /> and tested. <br /> Note: any exposed piping that is still filled with water at <br /> shutdown — including the makeup water Tine— should be <br /> electrically traced and insulated (by others). <br /> Steam Jet Basin Heaters <br /> Penberthy Houdaille bronze steam jet heaters ( to <br /> 3 /4 ") are available from Marley for freeze protection (instal- <br /> lation by others). Injectors install in a coupling provided in <br /> the side of the collection basin. Live steam, as required, is <br /> injected directly into the water. Condensed steam adds <br /> water to the basin, and the excess will exit the overflow of <br /> the tower. <br /> 20 <br />