DOE-2 Reference Manual Version 2.1 - DOE2.com

RATED-CFMRETURN-CFMthen the program will use COINCIDENT to calculate SUPPLY-CFM.Otherwise, if any of these conditions are not met, the programwill use NON-COINCIDENT to calculate SUPPLY-CFM. (CBVAV isnot included in the preceding list of variable volume systemsbecause its supply air flow rate is actually constant in thesupply duct. Only during the ceiling bypass operation in thezone does the supply air volume vary and that does not affectSUPPL Y-CFM.is the nominal capacity of the supply air fan in this system,as specified by the fan manufacturer. This keyword and itsassociated value are input by the user if he has chosen asupply fan, from the manufacturers' literature, that will beforced to operate above or below its rated capacity to meetthe flow rate of SUPPLY-CFM (or the flow rate calculated bythe program). The rating is in cfm at standard (sea level)conditions.This over- or under-sized fan may affect other equipment inthe system; therefore, the user should see alsoRATED-HCAP-FCFM, RATED-HEIR-FCFM, RATED-CCAP-FCFM,RATED-CEIR-FCFM, and RATED-SH-FCFM in SYSTEM-EQUIPMENT.is the design capacity (in standard, or sea level, cfm) of thesystem return air fan. The preceding discussion of keywordSUPPLY-CFM applies here, except that, if there is no dataentry, the program always assumes that return air flow equalssupply air flow minus zone exhaust (keyword EXHAUST-CFM inZONE-AIR instruction).Note: Although the outside ventilation air may vary inquantity (from the minimum allowed upward), as-a function oftime due to schedu 1 es or OA-CONTROL strategy, the flow ofoutside ventilation air is an uninterrupted flow of air aslong as the FAN-SCHEDULE is on for that hour (or ifNIGHT-CYCLE-CTRL intervenes to turn the fans on when theFAN-SCHEDULE is off). The outside ventilation air quantity isnot determined by the space heating and cooling demands.MIN-OUTSIDE-AIR is the minimum acceptable contant flow rate of fresh air,expressed as a decimal fraction of the maximum air supply flowrate. Note that the design flow rate for multiple zone,variable volume-type systems may be the concurrent peak flowrate, rather than the sum of individual zone peaks. (See thepreceding discussion of SUPPLY-CFM.)The user may alternatively, or additionally, specify outsideair quantities at the zone level (keywords OA-CHANGES,OA-CFM/PER, or OUTSIDE-AIR-CFM in the ZONE-AIR instruction).If a value is specified for this keyword and values are alsospecified for the zone level keywords OUTSIDE-AIR-CFM,OA-CHANGES, OA-CFM/PER, or EXHAUST-CFM, the zone level valuestake precedence over the system level value. If no zone levelvalue(s) are specified, the value specified here will be used.IV.214 (Revised 5/81)