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Operation and Maintenance Instructions On induced draft units provided with a belt drive arrangement as shown in Figure 3 all belt-tensioning bolts on the adjustable motor base should have an equal amount of exposed thread for proper pulley and belt alignment. On induced draft units provided with a direct drive arrangement as shown in Figure 4 no belts are provided and no adjustment is required. Figure 3: Belt Drive Arrangement Figure 4: Direct Drive Arrangement Page 16 of 34 www.evapco.com.au sales@evapco.com.au
Operation and Maintenance Instructions On forced draft units the belt tension is adjusted by turning the adjustment nut as circled below. Tension the belt by turning the nut counter-clockwise. Figure 5: Forced draft belt drive arrangement Gear Drives Induced draft units with gear drive systems require special maintenance. Please refer to the gear manufacturer’s recommended maintenance instructions. These will be enclosed and shipped with the unit. Air Inlet Inspect the air inlet louvers (induced draft units) or fan screens (forced draft units) monthly to remove any paper, leaves or other debris that may be blocking airflow into the unit. Fan System Capacity Control Capacity control can be achieved by (a) cycling of single speed motors, (b) two speed motors, or (c) variable speed drives. In all cases, if motors are idle for extended periods of time with water still being directed over heat transfer media, motor space heaters are suggested. Fan Motor Cycling Fan motor cycling requires the use of a single stage thermostat which senses the leaving water temperature (cooling towers), leaving fluid temperature (closed circuit cooler), and condensing temperature (evaporative condensers). The contacts of the thermostat are wired in series with the fan motor’s starter holding coil. Fan motor cycling is often found to be inadequate where the load has a wide fluctuation. In this method, there are only two stable levels of performance: 100% of capacity when the fan is on and approximately 10% of capacity when the fan is off. Please note that rapid cycling of the fan motors should be avoided as it can damage the motor. Controls should be set to limit a maximum of six (6) start/stop cycles per hour. Two Speed Motors The use of a two speed motor provides an additional step of capacity control when used with the fan cycling method. The low speed of the motor provides about 60% of full speed capacity. Two speed capacity control systems require a two speed motor, a two stage thermostat, and the proper two speed motor starter. The most common two speed motor is a variable torque single winding/consequent pole type. Two speed motors are also available with two internal windings. Be sure to select the proper sales@evapco.com.au www.evapco.com.au Page 17 of 34
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For Evapco Fibreglass Cooling Towers, Closed ... - EVAPCO.com.au

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