DOE-2 Reference Manual Version 2.1 - DOE2.com

vii. Example Control Strategies for SYSTEM-TYPE Equals HVSYSIf the user has not done so, he should read the General sUbsection (Sec.B.5.a of this chapter) before continuing here. That subsection containsinformation that is appropriate to these control strategies.In this SYSTEM-TYPE a single supply air duct provides hot air and outsideventilation air to each ZONE. This SYSTEM-TYPE has no mechanical coolingcapabil ity or humidity control. Under the correct conditions, the SYSTEM willattempt to cool the ZONE(s) with outside air. This SYSTEM-TYPE is mostcommonly referred to as the school heating and ventilating system. Air issupplied at a constant flow rate when the supply air fan is on. The SYSTEMwill have an economizer, unless the user specifies OA-CONTROL = FIXED in theSYSTEM-AIR subcommand. The economizer will attempt to maintain the mi xed(return and outside) air temperature at the value specified via HEAT-CONTROL.There are three major control strategies that are defined by the selectivespecification of values for the keywords HEAT-CONTROL, HEAT-TEMP-SCH,THERMOSTAT-TYPE, REHEAT-DELTA-T, and BASEBOARD-CTRL.These control strategies all involve one thermostat set point. Thedesired set pOint is specified with the keyword HEAT-TEMP-SCH (plus itsassociated SCHEDULE).The temperature of the air stream leaving the central heating coil isdetermined by the value specified (or defaulted) for the keyword HEAT-CONTROLin the SYSTEM-CONTROL subcommand:(a) . If HEAT-CONTROL = CONSTANT, the user should specify a value forHEAT-SET-T (SYSTEM-CONTROL subcommand) that will not overheat anyone ZONE in the SYSTEM. Some ZONEs, however, may be underheated.This can be remedied by specifying either zone coils or baseboardheaters. Unfortunately, with this strategy a correct value forHEAT-SET-T for heating may be too high for cooling with outsideventilation air. -(b)(c)If HEAT-CONTROL = RESET or SCHEDULED, the temperature of the airleaving the central heating coil will be based upon a user-specifiedRESET-SCHEDULE or SCHEDULE. The hourly values specified in theSCHEDULE should be such that no ZONE becomes overheated. Thisapproach may lead to the underheating of some ZONEs, in which case,zone coils or baseboard heaters may be used. When HEAT-CONTROL =SCHEDULED, it affords the opportunity to have seasonal reset of thecentral heating coil temperature, as opposed to the approach (a).These strategies, especially HEAT-CONTROL = RESET, allow the SYSTEMto take better advantage of the outdoor air temperature for coolingby ventilation.If HEAT-CONTROL = COLDEST, the temperature of the air leaving thecentral heating coil will be automatically set by the program toheat (or cool) the ZONE with the lowest relative temperature in itsheating THROTTLING-RANGE.I V.151 (Revised 5/81)