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If the water in the Bay freeze, coiled tubing can burst, causing the cost of repair coil, disruption of service, and possibly water damage to the building. Water in the Bay can be frozen due to the cold air, cooling of certain metal surfaces below the freezing point of water. Protective device called freezestat must be installed on all the lines that are likely to be vulnerable to freezing conditions. It is a long, flexible tube that is attached to the exit face of the coil. If a small extent (about 15 cm), phone falls to a temperature of 0C, freezestat opens the electric switch is included in the system, which takes at least two things: (1) disables fans and (2) closes an open-air and exhaust dampers.....
In most cases preheat coils (if they are used in the system) are equipped with freezestats, and even some cooling coils that are not drained of their water in the winter should be so equipped. Many designers provide a circulating-water pump on hot-water preheat coils in order to prevent low water velocities. It is during periods of low water velocity that freezeups are most likely to occur. Locating the preheat coil in the mixed-air stream has the advantage of warming the outdoor air before reaching the coil and thus helps to prevent freezeups. |
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