DOE-2 Reference Manual Version 2.1 - DOE2.com

1. Four-Pipe Induction Unit System (FPIU)OUTSIDE AJR __lHEr:r - - I(UOVE~YI _~_ ----, PRE HEAT (DOll ~IG HE" T 1 tiC;{OIL I :ECONOMIZER: COIl..COILCOIL,__ ..J! I ~t=====I~%-t====1RETURNAIRaTHHWScON S~:;~!~E~I III II IL ___ -.lPR !r1ARY"RsurrL YFM,MIXEDAIRCONTROLSCH'"S111 XED;\lRt,1-I TEMS SHOWN I N DASHED BOXESARE OPTIONAL COMPONENTSThe Four-Pipe Induction Unit system, illustrated above, is identical tothe Two-Pipe Induction Unit system (TPIU), except that the coil located in eachterminal induction unit is connected to two different piping systems, one circulatingcooled fluid and one Circulating heated fluid. Thus, the inductionunit in one zone can provide heating, by selecting flow from the heated fluidcirculation piping, at the same time that a unit in another zone is providingcooling, by selecting flow from the cold fluid circulating system. Changeoverenergy losses are minimal, and are not taken into account by the program. Thecontrol system for each unit provides automatic switchover from cool ing toheating (and vice versa) as required to maintain space temperature conditions.With the exception noted above, the discussion of system design features andoptions for System TPIU also applies to this system.Exhaust fan(s) are optional for any or all zones. The Btu equivalent ofthe moisture that is added to the air stream, to maintain a minimum humidity,is passed to the PLANT program as a heating load.A number of optional features and control strategies can be speCified forthis system. The optional features are discussed in Table IV.2 and thesection entitled, "Explanation of System Options" (immediately following TableIV.2). The possible control strategies for this system are discussed in Sec.B.5 of this chapter. It is highly recommended that the user read that portionof Sec. B.5 that is appl icable to this system.IV.57 (Revised 5/81)