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DOE-2 Reference Manual Version 2.1 - DOE2.com

DOE-2 Reference Manual Version 2.1 - DOE2.com

DOE-2 Reference Manual Version 2.1 - DOE2.com

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RETURN-STATICRETURN-EFFMAX-FAN-RATIOMIN-FAN-RATIORETURN-DELTA-T, will be used in the absence of data entriesfor RETURN-STATIC and RETURN-EFF.is an alternative to specifying values for RETURN-DELTA-T andRETURN-KW. It is used in conjunction with RETURN-EFF. It isdefined as the total or static pressure produced by the systemreturn air fan at design flow rate (see keyword RETURN-EFF foradditional discussion). Design flow rate is the user inputvalue for the keyword RETURN-CFM (see SYSTEM-AIR instruction)or, if no data entry is made for that keyword, the calculatedreturn air flow rate.is an alternative to specifying values for RETURN-DELTA-T andRETURN-KW. It is used in conjunction with RETURN-STATIC. Itis defined as the overall efficiency of the return air fan' atdesign conditions (expressed as a decimal fraction). Overallefficiency is the combined efficiency of the fan and motor -see keyword SUPPLY-EFF for additional discussion.Note: If data entries are omitted for RETURN-DELTA-T,RETURN-KW, RETURN-STATIC and RETURN-EFF, the program assumesthere is no return fan for this system.is the maximum air flow through the fan, expressed as afraction of the design flow rate.is the minimum air flow through the fan (not through thesystem), expressed as a fraction of the design flow rate.When a variable air volume system requires less air flow, afan bypass is uti,lized.LOW-SPEED-RATIOS is used for TWO-SPEED fans or DUAL-SPEED compressors. Thus,the unit being described has the capability of controllingcapacity in two steps, or being off. The values entered forthis keyword are the ratio of air-flow, energy input, as wellas heating and cooling at low speed to those at high (design)speed. These values are under the following conditions:i) in PTAC for FAN-CONTROL = TWO-SPEED,ii) in RESYS for COMPRESSOR-TYPE = DUAL-SPEED.The list of four values to be entered are:1)l?w speed cfm for TWO-SPEED fans, or 1.0 for DUAL-SPEEDh 1 gh speed cfmcompressors,2)3)EIR at low speedEIR at high speed'HEATING-CAPACITY at low speedHEATING-CAPACITY at high speed'andIV.227 (Revised 5/81)

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