DOE-2 Reference Manual Version 2.1 - DOE2.com

. Examplesi. Example Control Strategies for SYSTEM-TYPE Equals MZS, DDS, or PMZSIf the user has not done so, he should read the General subsection (Sec.IV.B.5.a) before continuing here. That subsection contains information thatis appropriate to these control strategies and SYSTEM-TYPEs.In these three SYSTEM-TYPEs, the air flow rates in the individual coldand hot air ducts are automatically varied by the program, from one hour tothe next hour, in an attempt to deliver the correct proportions of cold airand hot air (at the deck temperatures specified via COOL-CONTROL andHEAT-CONTROL) to meet the desired ZONE temperature, which is specified inCOOL-TEMP-SCH and HEAT-TEMP-SCH. The program treats MZS and DDS thermally thesame. The twelve major control strategies for each of these SYSTEM-TYPEs arelisted in Table IV.25. Each strategy is defined by the selective specificationof values for the keywords MIN-CFM-RATIO, COOL-CONTROL, HEAT-CONTROL,COOL-TEMP-SCH, HEAT-TEMP-SCH, and THERMOSTAT-TYPE.In these strategies (dual duct strategies), the term constant volume flowrefers to the hourly volume of air entering the ZONE, not the quantity of airflowing in the individual cold or hot air ducts. The air volume flowing inthe cold air duct may vary from zero to a maximum of the design cooling flowrate (that is, the ASSIGNED-CFM, or in its absence, the amount of cold airrequired to meet the ZONE peak cooling load). The air volume flowing in thehot air duct is similarly simulated.Likewise, the term variable volume flow for dual duct systems refers tothe supply air entering the ZONE, not the quantity of air flowing in the individualcold and hot air ducts. The blended hot and cold quantity of airentering the ZONE may vary from a minimum of MIN-CFM-RATIO to a maximum of thedesign flow rate, assuming the supply air fan is on.Use of the keyword DUCT-DELTA-T with these SYSTEM-TYPEs can cause anover-estimate of the heating supply air temperature, when the heating coil isnot active.The heat from the supply air fan is added, by the program, to the airstream ahead of the hot and cold decks. The effect of the humidifier, ifspecified, is added to the supply air stream.Example:Constant Volume Cooling and Heatin with User-controlled Cold and HotDeck Temperatures for MZS, DDS, an a PMZS(with COOL-CONTROL = CONSTANT, RESET, or SCHEDULEDand HEAT-CONTROL = CONSTANT, RESET, or SCHEDULED)This example control strategy is an MZS or PMZS system with constantvolume flow of mixed air entering the ZONE for both cooling and heatlng. Inthis SYSTEM-TYPE, with this strategy only, the cold air damper and the hot airdamper are physically linked together (at 90 degrees to each other). Openingthe hot air damper closes the cold air damper, and vice versa. Therefore,IV.lll (Revised 5/81)