DOE-2 Reference Manual Version 2.1 - DOE2.com

i. Two-Pipe Fan Coil System (TPFC)2-PO$ITIO~3-wAY VALVE3-WAYU 1 VERT1 NGV'\LVEiCIRCULATINGPUMPS1UNITFA' (OJ'---~----lt- ,­,-- - -11------. 1-- 1 .,ZONENO. 3J_"~jI , I I I\ OUTSIDE I I I IL_~~R ___ I L ___ ~ L __ ~AIR- - -"1,, 0: ,I L.. ______ -1IITEMS SHO''';NIN DASHED BOXESARE OPT! ONAl COMPON~NTSThe Two-Pipe Fan Coil system, illustrated in the schematic above, canprovide both heating and cooling to a number of individually controlledzones. However, all zones served by the system must be operating in the samemode (i .e., either heating or cooling) at any given time.The fan coil unit consists of a filter (not shown), a combinationheating/cooling coil, and a fan. The coil is connected to a piping systemthat can provide either hot or cold water (according to the prevail ing mode ofoperation as defined by the HEATING-SCHEDULE and COOLING-SCHEDULE). The unitcan provide a fixed quantity of outside air ventilation or merely recirculateconditioned air. Exhaust fan(s) are optional for any or all zones.Temperature control is achieved by throttl ing the flow of water throughthe heating/cooling coil. The control thermostat commonly used for this typeof system has separate heating and cool ing set points.Note that the pumping energy associated with this system is accounted forin the PLANT program, rather than in the SYSTEMS program.Note that fan coil units, particularly the smaller direct-driveunits, may not be available with a fan capacity that matches the calculatedvalue. Therefore, assignment of the fan capacity of a specific, commerciallyavailable unit is recommended for improved simulation accuracy. Analternative to this is, if the user has to select a fan that is significantlydifferent in capacity from the calculated value (that is, one that will beforced to operate above or below its rated capacity to meet the calculatedvalue), he may elect to specify data for the keyword RATEO-CFM (see ZONE-AIRcommand) .IV.45 (Revised 5/81)