DOE-2 Reference Manual Version 2.1 - DOE2.com

iv. Example Control Strategy for SYSTEM-TYPE Equals TPFC, FPFC, HP, RESYS, orPTACIf 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 and SYSTEM-TYPEs.There is only one major control strategy (for each of these SYSTEM-TYPEs) thatis defined by the selective specification of values for the keywordsCOOL-TEMP-SCH, HEAT-TEMP-SCH, MAX-FLUID-T, MIN-FLUID-T, FLUID-HEAT-CAP,NATURAL-VENT-SCH, VENT-TEMP-SCH, and NATURAL-VENT-AC.SYSTEM-TYPE Equals TPFC or FPFCThe Two Pipe Fan Coil (TPFC) SYSTEM-TYPE is a "zonal" type that has a centralcooling source, a central heating source, and a pipe loop with a workingfluid, which flows to all the ZONEs. The loop provides either cooling fluidor heating fluid to all the fan coil units, which are located in the ZONEs.This means that all ZONEs in the SYSTEM must either be in the cooling mode orthe heating mode. The decision of when to switch the TPFC SYSTEM from coolingto heating, and vice versa, is made by the user and is expressed via the keywordsCOOLING-SCHEDULE and HEATING-SCHEDULE (see SYSTEM-CONTROL subcommand).The SCHEDULEs referenced by COOLING-SCHEDULE and HEATING-SCHEDULE must notoverlap. Each TPFC fan coil unit has a constant volume supply air fan, oneheat exchanger coil, a modulating control valve, and a two set point thermostat.The desired set points are specified, respectively, with the keywordsCOOL-TEMP-SCH andHEAT-TEMP-SCH (plus their associated SCHEDULEs).The Four Pipe Fan Coil (FPFC) SYSTEM-TYPE, also a "zonal" type, has acentral cooling source, a central heating source, and two pipe loops, one forcooling and one for heating. The FPFC fan coil units are identical to the TPFCfan coil units except the FPFC units have two heat exchanger coils. Dependingupon the hourly values referenced by COOLING-SCHEDULE and the HEATING-SCHEDULE,either cooling or heating, or both, can be made available at any time to theZONEs. That is, SYSTEM-TYPE = FPFC permits some ZONEs to be cooled whileother ZONEs are being heated.Cooling Mode for TPFC and FPFC - This explanation assumes THERMOSTAT-TYPE =PROPORTIONAL. At calculated ZONE temperatures above the coolingTHROTTLING-RANGE, the cooling output of the ZONE fan coil unit is at themaximum as calculated or specified. As the calculated ZONE temperature dropsfrom the top to the bottom of the cooling THROTTLING-RANGE, the cooling outputdecreases linearly from maximum to zero. For calculated ZONE temperaturesbelow the cooling THROTTLING-RANGE, the cooling output of the ZONE fan coilunit remains at zero. The air flow rate is always constant, assuming theFAN-SCHEDULE is on.Heating Mode for TPFC and FPFC - At calculated ZONE temperatures above theheatlng THROTTLING RANGE, the heating output of the ZONE fan coil unit iszero. As the calculated ZONE temperature drops from the top to the bottom ofthe heating THROTTLING-RANGE, the heating output of the ZONE fan coil unitincreases linearly from zero to its maximum, as calculated or specified. AtZONE temperatures below the heating THROTTLING-RANGE, the heating outputremains at the maximum. The air flow rate is always constant, assuming theFAN-SCHEDULE is on.IV.137 (Revised 5/81)