User Guide

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D. Design Requirements Unique to Split Vent Systems
Table 7.15 summarizes all split vent options. Illustrations of split vent systems are shown in Figure 7.14. In addition to the
requirements in Part VII-A, observe the following design requirements:
1. Permitted Terminals for Split Venting:
Rigid Vent Systems (Vent Options 25-26)–Ventterminatesinaplainend(couplingforPVC).IntaketerminatesinaPVC90
sweep elbow pointing down.
Use of rodent screens (not supplied) is generally recommended for both terminations. These can be fabricated from 2 x 2
(1/2” mesh) stainless steel screen. They are installed as shown in Figure 7.18.
Air Intake Terminals (Vent Options 25-26) - All split venting options shown in Tables 7.15 terminate in a PVC 90 sweep
elbow pointing down. Use of a rodent screen is generally recommended for the intake termination.
2. Vent Terminal Location –Observethefollowingclearancesfromroofmountedventterminals(alsoseeFigure7.14):
 • Bottomofterminalmustbeatleast12”abovethenormalsnowlineanticipatedontheroof.
 • Exhaustopeningmustbeatleast2ftaboveanyportionoftherooforstructurelocatedwithinhorizontallywithin10ft.
3. Horizontal Air Intake Terminal Location - Observe the following limitations on the intake terminal location (also see Figure
7.14):
 • Thebottomofallterminalsmustbeatleast12”abovethenormalsnowline.Innocaseshouldtheybelessthan12”
above grade level.
 • Ifpossible,installtheintaketerminalonawallawayfromtheprevailingwind.Reliableoperationofthisboilercannot
be guaranteed if the intake terminal is subjected to winds in excess of 40 mph.
 • Airintaketerminalmustnotterminateinareasthatmightcontaincombustionaircontaminates,suchasnearswimming
pools. See WARNING on page 11.
FIGURE 7.14: SPLIT RIGID VENT SYSTEM (VENT OPTIONS 25-32 - CPVC SYSTEM SHOWN IN ABOVE EXAMPLE)