C NC NO M 1 2 3 4 5 1 2 3 4 5 ANSWERS TO FAN SYSTEM WITH MANY ERRORS POTENTIAL ISSUES -1- What are the errors in the mechanical arrangement? -2- What are the errors with the pneumatic arrangement? -3- What are the errors with the safety circuit? -4- What are the errors with the wiring? Answers are on page XXX PROBLEM AREAS -1- The return damper should be NO not NC. -2- The spring ranges on the mixing dampers are incorrect. Exhaust and return should be 8#-13# and fresh air should be 5# to 10#. -3- Another smoke detector and another sprinkler head (high limit) should be installed in the return air. -4- PE1 should be NO, not NC. -5- The hand position on the starter bypasses the safeties. It should not. -6- The solenoid valve voltage is incorrect. It should be 120V. -7- There is no high limit from outside air on the dampers for cooling season. There should be one. -8- The mixed air controller is RA, set at 75 °F. It should be DA, set at 55°F. -9- The valve ranges on V2 and V3 are reversed. -10- The porting on V3 is incorrect. C and NC should be reversed. -11- There is no minimum positioner. One should be added. -12- There is no sequencing between free cooling and heating. It should be added. -13- The cooling coil must be winterized or the low limit moved upstream of the heating coil. -14- The safety circuit is fed with EP air not main air. 10-184 RETURN FAN SUPPLY FAN 5#-10# DM3 5#-10# DM2 8#-13# DM1 OUTDOOR AIR EXHAUST AIR NC NC NC SUPPLY AIR COOLING COIL HEATING COIL SMOKE DETECTOR V2 4#-8# V3 9#-13# C NC NO CWR CWS NO HWR HWS C NC EP1 24V MIXED AIR RETURN AIR TEMP. TEMP. PE1 10# NC B M 1 2 3 B M 1 2 3 RC1 RA RC2 DA MIXED AIR SET 75˚F RETURN AIR SET 70˚F RESTRICTOR 120 V OFF EP1 FAN COIL PE1 HAND AUTO SMOKE DETECTOR
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