York DC SERIES Installation Manual

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York DC SERIES Installation Manual Manual pdf 33 page image

5120410-XIM-B-0216Johnson Controls Unitary Products 33Figure 26: Belt AdjustmentCFM Static Pressure and Power-Altitude and TemperatureCorrectionsThe information below should be used to assist in application ofproduct when being applied at altitudes at or exceeding 1000feet above sea level.The air flow rates listed in the standard blower performancetables are based on standard air at sea level. As the altitude ortemperature increases, the density of air decreases. In order touse the indoor blower tables for high altitude applications,certain corrections are necessary.A centrifugal fan is a "constant volume" device. This meansthat, if the rpm remains constant, the CFM delivered is thesame regardless of the density of the air. However, since the airat high altitude is less dense, less static pressure will begenerated and less power will be required than a similarapplication at sea level. Air density correction factors are shownin Table 20 and Figure 30.AAABSPAN LENGTHDEFL. FORCEC** NEVER LOOSENProcedure for adjusting belt tension:1. Loosen six nuts (top and bottom) A.2. Adjust by turning (B).3. Never loosen nuts (C).4. Use belt tension checker to apply a perpendicularforce to one belt at the midpoint of the span asshown. Deflection distance of 4mm (5/32”) isobtained.To determine the deflection distance from normalposition, use a straight edge from sheave to sheave asreference line. The recommended deflection force is asfollows:Tension new belts at the max. deflection forcerecommended for the belt section. Check the belttension at least two times during the first 24 hours ofoperation. Any retensioning should fall between the min.and max. deflection force values.5. After adjusting retighten nuts (A).