DOE-2 Reference Manual Version 2.1 - DOE2.com

s. Packaged Single Zone Air Conditioner with Heatingand Subzone Reheating Options (PSZ)This hybrid system/plant, usually larger than a PTAC, cools by the directexpansion of a refrigerant and may optionally heat with gas, hot water, or anelectric resistance heater. This unit is normally considered a commercialunit. It provides constant volume air to a control zone and constant- orvariable-air volume flow to optional subzones. If the user desires to havevariable volume air to all zones, that can be modeled by using the PVAVSsystem. This forced-air packaged unit may be either a unitary system (rooftopunit or outside-the-wall unit) or it may be a split unit (partially inside andpartially outside). It mayor may not require ducting. In its most basicconfiguration the PSZ system consists of a compressor, an air-cooled condenser,an evaporator with a fan supplying cooled air to the indoors, a filter (notshown), and a thermostat. The optional features are discussed in Table IV.2and the section entitled, "Explanation of System Options" (immediatelyfollowing Table IV.2). The PSZ unit can optionally be specified with acentral heating device, subzone reheating device(s), outside ventilation air,and economizer cooling. The supply fan may be either a blowthrough or adrawthrough fan, with the fan motor either inside or outside the air stream.The condenser fan operates automatically on demand. An exhaust air fan andlora return air fan may optionally be specified. The thermostat may be specifiedwith night setback and night cycle control.The possible control strategies for this system are discussed in Sec. B.5of this chapter. It is highly recommended that the user read that portion ofSec. B.5 that is applicable to this system.Table IV.21 shows the commands and keywords that must be entered forsimulation of this system, as well as those that are applicable but optional(i.e., program uses default value if entry is omitted).joUTSIDE--AlII: _L ___ _:-RETUIi;l, FAN I,[~IIf~!}, [~~H.l},i--1£@..).I--IFtir--H--:='1I I I I II SUBZONE I $UeZOliE IHo.21,,0.11: I I I I~_ -L_ --L-ITEMS SI10"" IN DASMED BOXESARE OPTIONAL COMPONENTSIV.87 (Revised 5/81)