9
3) MinimumVentandAirIntakeLengths-Minimumventlengthis2ft.Minimumairinletlengthis2ft.
4) PermittedTerminalsforHorizontalVenting(VentOptions1,2)-Theventterminaliseitherateeoranelbow
suppliedbytheventsystemmanufacturerandequippedwitharodentscreen.Ventsystemmanufacturer’spart
numbersforthesettingsareshowninTable6.5.Insomecases,theelbowsandteesshowninTable6.5require
separaterodentscreens.Whenthisisthecase,ventmanufacturerpartnumbersfortheseadditionalpartsareshown
inTable6.5alongwiththeterminationtting.
 Theairintakettingonahorizontalventsystemsisalwaysa90degreeelbowwitharodentscreen.Thiselbowis
madeoutofthesamematerialastherestoftheairinletsystem(eithergalvanizedorPVC)andisinstalledasshown
in Figure 6.1.
5) HorizontalVentandAirIntakeTerminalLocation-Observethefollowinglimitationsontheventterminallocation
(alsoseeFigure6.3):
• Ventterminalsmustbeatleast1footfromanydoor,window,orgravityinletintothebuilding.
• Maintainthecorrectclearanceandorientationbetweentheventandairintaketerminals.Theventandair
intaketerminalsmustbeatthesameheightandtheircenterlinesmustbebetween12and36inchesapart.Both
terminalsmustbelocatedonthesamewall.
TheVentOption#1columninTable6.2adescribesahorizontaldirectventsystemusing3”ventpipe.Fromthis
column,weseethataCHG150mayhaveaventlengthofupto55ft.Therst90elbowandtheterminationelbow
arenotconsidered.FromTable6.6,theequivalentlengthofthe3”45elbowis4ftandtheequivalentlengthofthe
3”90degreeelbowis5.5ft.Themaximumallowablerunofstraightpipeonthissystemistherefore:
55ft–4ft–5.5ft=40ft
Since the planned installation has only 14 ft of straight pipe, the planned vent length is acceptable.
Figure 6.1: Horizontal Direct Venting (Vent Options 1,2)