2.2 CHECKING FOR AIR LEAKS AT SUPPLY FANS After your control service mechanic has verified that there are no air leaks in your fan systems, turn the units on and off, individually, while reading the normal air consumption for each unit. Use the chart on page eleven of this report to record the normal air consumption for each unit. This information will provide value during future assessments regarding air leaks. If you have not noted the normal consumption per fan system, you can estimate the consumption by counting the instruments on the system and allow the manufacturer's controller value relating to estimated air consumption per instrument. Follow the same manning arrangement as with the exhaust fans. One person should be at the flow meter and the other at central control to operate the fans. Stop and start the fans one at a time while noting the air consumption relative to the expected air consumption for each fan system. If one fan is using more air than expected, investigate the cause at the fan system. THERMOSTAT LOOPS AND MAIN AIR DISTRIBUTION If the exhaust fans and the supply fans prove to have normal consumption, you have narrowed the likely location of the leak(s) to the third and largest component of your pneumatic system, the thermostat loops and main air distribution piping. The investigation, at this stage, must be approached logically to reduce frustration and costs. We suggest that you obtain a floor plan of the building to plot the maximum branch pressure readings establishing a pressure picture of the whole piping system. The areas of the lowest pressures are the most likely areas to find significant air leaks. 9-167
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