York ZV Series Installation Manual

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5370598-BIM-C-0518Johnson Controls Ducted Systems 43Supply Air Drive AdjustmentAt unit start-up, the measured CFM may be higher or lower thanthe required CFM. To achieve the required CFM, the speed ofthe drive may have adjusted by changing the datum diameter(DD) of the variable pitch motor sheave as described below:Use the following tables and the DD calculated per the aboveequation to adjust the motor variable pitch sheave.EXAMPLEA 4 ton unit was selected to deliver 1,700 CFM with a 1.5 HPmotor, but the unit is delivering 1,400 CFM. The variable pitchmotor sheave is set at 3 turns open.Use the equation to determine the required DD for the newmotor sheave,Use Table 22 to locate the DD nearest to 2.28 in. Close thesheave to 2 turn open.New BHP= (Speed increase) 3 • BHP at 1,400 CFM= (Speed increase) 3 • Original BHP= New BHPNew motor Amps= (Speed increase) 3 • Amps at 1,400 CFM= (Speed increase) 3 • Original Amps= New AmpsBefore making any blower speed changes review theinstallation for any installation errors, leaks or undesirablesystems effects that can result in loss of airflow.Even small changes in blower speed can result insubstantial changes in static pressure and BHP. BHPand AMP draw of the blower motor will increase by thecube of the blower speed. Static pressure will increaseby the square of the blower speed. Only qualifiedpersonnel should make blower speed changes, strictlyadhering to the fan laws.1,700 CFM1,400 CFM 1.88 in. = 2.28 in.Table 22: Motor Sheave Datum Diameters1VL34x7/8(1-1/2 HP Motor)1VL44x7/8(1-1/2 HP Motor)1VL40x7/8(1-1/2 HP Motor)1VM50x7/8(2 HP Motor)Turns Open Datum Diameter Turns Open Datum Diameter Turns Open Datum Diameter Turns Open Datum Diameter0 2.9 0 4.0 0 3.6 0 4.41/2 2.8 1/2 3.9 1/2 3.5 1/2 4.31 2.7 1 3.8 1 3.4 1 4.21-1/2 2.6 1-1/2 3.7 1-1/2 3.3 1-1/2 4.12 2.3 2 3.6 2 3.2 2 4.02-1/2 2.4 2-1/2 3.5 2-1/2 3.1 2-1/2 3.93 2.3 3 3.4 3 3.0 3 3.83-1/2 2.2 3-1/2 3.3 3-1/2 2.9 3-1/2 3.74 2.1 4 3.2 4 2.8 4 3.64-1/2 2.0 4-1/2 3.1 4-1/2 2.7 4-1/2 3.55 1.9 5 3.0 5 2.6 5 3.4Belt drive blower systems MUST be adjusted to thespecific static and CFM requirements for the application.The Belt drive blowers are NOT set at the factory for anyspecific static or CFM. Adjustments of the blower speedand belt tension are REQUIRED. Verify proper sheavealignment; tighten blower pulley and motor sheave setscrews after these adjustments. Re-checking set screwsafter 10-12 hrs. run time is recommended.