DOE-2 Reference Manual Version 2.1 - DOE2.com

iii. Example Control Strategy for SYSTEM-TYPE Equals SZRH and PSZIf the user has not done so, he should read the General subsection (Sec.B.5.a of this chapter) before continuing here. That subsection contains informationthat is appropriate to the control strategies for these SYSTEM-TYPEs.There is only one major control strategy that is defined by the selectivespecification of values for the keywords COOL-TEMP-SCH, HEAT-TEMP-SCH, andREHEAT-DELTA-T.In these SYSTEM-TYPEs a single supply air duct provides either cold or hotair, at constant volume, to a control ZONE, and (optionally at variable flow)to one or more subZONEs. The control ZONE is the first ZONE specified by theuser in the ZONE-NAMES keyword list (see SYSTEM command). The ZONE chosen asthe control ZONE should be the one that is the easiest to heat in the winterand the hardest to cool in the summer. If this criterion is not met, it willbe impossible for the subZONE reheat coils to maintain temperature control inthe sub ZONEs.The cooling supply air temperature is controlled at the SYSTEM level viaCOOL-TEMP-SCH for the control ZONE. The subZONEs control only the reheat coilunless the variable air volume option is used.Space heating is controlled at both the SYSTEM level and the subZONElevel. The SYSTEM level heating is controlled via HEAT-TEMP-SCH for thecontrol ZONE and the ZONE level heating is controlled via HEAT-TEMP-SCH forthe subZONE(s). The heating for the subZONEs is accomplished by zone (reheat)coils.If the SYSTEM does not have one single ZONE that meets the criterion,stated above, for a control ZONE, the following can be done. The user canintervene in the automatic process of calculating the design flow rate byspecifying values for ASSIGNED-CFM, AIR-CHANGE/HR, or CFM/SQFT (see ZONE-AIRsubcommand) for those ZONEs that are improperly conditioned. Often, such acorrection for heating in the winter will be detrimental to the coolingprocess in the summer. This is not surprising and is quite indicative of thisSYSTEM-TYPE in real life.The heat from the supply air fan is added, by default, downstream fromthe cooling coil, unless the user specifies FAN-PLACEMENT = BLOW-THROUGH. Theeffect of the humidifier, if specified, is added to the mixed air stream.Examp 1 e:Constant Volume Cooling and Heating Strategy for SZRH and PSZ with ZONEReheatingThis strategy involves two thermostat set points in the control ZONE, onefor cooling and one for heating. The control ZONE does not have a zone (reheat)coil. In the subZONEs, only the heating set point is used, to controlthe reheat coils (unless a variable air volume capability has been specified).The temperature of the cold air stream (cooling coil temperature) is heldconstant throughout each hour for simulation purposes, but varies with eachIV.133 (Revised 5/81)