DOE-2 Reference Manual Version 2.1 - DOE2.com

Example:Variable Volume Cooling / Constant Volume Heating with User-controlledCold Deck Temperature for VAVS, PVAVS, CBVAV, and RHFS(with COOL CONTROL _ CONSTANT)The cooling is accomplished by a variable air volume flow. In thisexample, the temperature of the cold air stream (air temperature leaving thecooling coil) is set by the user at a fixed value. The variable volume flowof cooling air is controlled at the ZONE level with the keyword COOL-TEMP-SCH.The heating is accomplished at the ZONE level by a constant air volumeflow over a variable temperature zone coil, located in the supply air duct.The temperature of the hot air stream (zone coil temperature) is controlled atthe ZONE level with the keyword HEAT-TEMP-SCH.Cold Deck Air Flow and Temperature - The cooling coil temperature is set bythe user at a flxed value for all hours of the year. At calculated ZONEtempera- tures above the cooling THROTTLING-RANGE, the air flow rate in theair duct is at the maximum. As the calculated ZONE temperature drops from thetop to the bottom of the cooling THROTTLING-RANGE, the air flow rate in theduct drops from the maximum to the MIN-CFM-RATIO. For all calculated ZONEtemperatures below the cooling THROTTLING-RANGE the air flow rate remains atthe MIN-CFM-RATlO.Zone Coil Temperature - As the calculated ZONE temperature drops from the topto the bottom of the heating THROTTLING-RANGE, the zone coil output increaseslinearly from zero at the top of the heating THROTTLING-RANGE to maximum atthe bottom of the heating THROTTLING-RANGE.Procedure:(1) Specify SYSTEM-TYPE = VAVS, PVAVS, CBVAV, or RHFS in the SYSTEMcommand.(2) Specify MIN-CFM-RATIO (in either the ZONE command or in theSYSTEM-TERMINAL subcommand) equal to some value less than 1.0(MIN-CFM-RATIO = 1.0 will simulate a constant volume system). Ifthe user does not specify a value for MIN-CFM-RATIO, the programwill calculate the value, based upon outside air flow rate or peakheating load. The value of MIN-CFM-RATIO along with THERMOSTAT-TYPE= PROPORTIONAL, assures a variable volume air flow entering thisZONE(s) for cooling and a constant volume air flow entering theZONE(s) for heating.(3) Specify COOL-CONTROL in the SYSTEM-CONTROL subcommand equal toCONSTANT, or allow it to default. Also specify COOL-SET-T equal tothe desired fixed cooling coil temperature, normally equal to orgreater than MIN-SUPPLY-T. This establishes the temperature of thecooling supply air that will be sent to all ZONEs in the SYSTEM. Ifthe user does not specify a value for COOL-CONTROL, it will defaultto CONSTANT and COOL-SET-T will default to MIN-SUPPLY-T.I V .130 (Revised 5/81)