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indamental Series Item : Choosing the Best HVAC System filet//c~windows/TEMP/0,2637,16287,OO.h~ <br />30 <br />operates but capabilities are also fixed by design. The size of the cooling and <br />coils are also fixed. <br />One manufacturer is responsible for the final unit. ManufacturerTmatched con <br />have certified .ratings and perFormance data and factory assembly allovus impl <br />quality control and reliability. There are a number of manufacturers, so units z <br />available, but equipment life, may be relatively short, usually 10-15 years as cc <br />larger equipment which may have life expectancies of 20-25 years.. Manufacti <br />instructions and multiple-unit arrangements simplify the installation through re <br />tasks.. <br />System operation is simple. Generally, trained operators are not required and <br />mechanical and electrical space is required than with central systems. Howev <br />maintaining the units is more difficult because of the many pieces of equipme <br />location, which is usually in occupied spaces. <br />Initial cost is usually low but operating cost may be higher than for central sys~ <br />will be the case when the unitary equipment efficiency is less than that of the <br />system components. Also, energy use may be greater because fixed unit size <br />require oversizing for some applications. Far applications such as leased offic <br />energy use can be metered directly to each tenant. Units can be installed to c <br />one space at a time as a building is completed, remodeled, or as individual ar <br />leased and occupied. Another energy management opportunity with unitary s~ <br />that units serving unoccupied.spaces can be turned off locally or from a cents <br />without affecting occupied spaces. <br />Summary <br />A solid understanding of the various types of commercial HVAC systems and their s~ <br />important for the energy manager because the position often calls for being the owns <br />representative to work with others to ensure that the owner gets the environmental s <br />will best fit his needs. <br />Samuel C. Monger, CFM, CDSM, is the principal of the energy systems training firm, <br />Monger Worldwide Consulting. The author of numerous articles and books on perforr <br />testing and evaluation of HVAC/R systems, Monger is a nationally recognized energy <br />svstems educator and energv engineering professional. <br />Copyright ©2000 by Business News Publishin Co. <br />