Figure 50 _Vent Pipe Termination for Non-Direct Vent and Ventilated Combustion Air System
Roof Terminatbn (Preferred)
(305mm)
minimum clearance
above highest ant_dpated
snow bvel maxim um of
24 _n (61 gem) above roof
Abandoned masonry
used as raceway
(percode)
12 _n m_n (305 mm)from
overhang or roof
6 _n 152mm) m_n_mum clearance
bergen wa _and end o vent p_pe
10 _n (254mm) m_mum p_pe bngh
S_de wal_ term_naSon
w_h 2 eFbows (preferred)
Size the Vent and Combustion Air Pipes
General
Furnace combustion air and vent pipe connections are sized
for 2-in. (50 mm ND) PVC/ABS DWV pipe. The combustion air
and vent pipe connections also accommodate 60mm
polypropylene venting systems with outside diameters of
approximately 60 mm (2-3/8 inches). Any pipe diameter
change should be made outside furnace casing in vertical pipe.
Any change in diameter to the pipe must be made as close to
the furnace as reasonably possible.
The Maximum Vent Length for the vent pipe and combustion air
pipe (when used) equals the Maximum Equivalent Vent Length
(MEVL) in Table 14 or Table 16, minus the number of fittings
multiplied by the deduction for each type of fitting used from
Table 15.
OPTIONAL CONFIGURATION FOR COMBUSTION
AIR INLET PIPE
In applications where there is a risk of excessive mois-
ture entering the combustion air inlet pipe, a moisture
trap may be added to the inlet pipe to help prevent
moisture from entering the furnace from the combus-
tion air inlet pipe. See Figure 51.
When sizing venting systems, the equivalent length of
the optional moisture trap (15 feet/5 M) must be taken
into account
Maintain 12 _n (305me)
m_n_mum cbarance
above h_ghest ant_dpated
snow level or grade
whichever _s greater
Maintain 12 _n (305me)
m_n_mum cbarance
above h_ghest ant_dpated
snow level or grade
whichever _s greater
SidewalF Ter m_nat bn
w_th Stra_gH P_pe (preferred)
A0509f
Optional Combustion Air Inlet
Moisture Trap
As an option to prevent moisture from trickling into the furnace
vestibule, a trap can be installed in the intake air pipe near the
furnace. Connecting a drain line to the trap is optional as trace
amounts of moisture will evaporate into the intake air stream. If
the combustion air inlet is located near a moisture exhaust
duct, or there are other concerns of excessive moisture being
drawn into the combustion air inlet, it is encouraged to connect
a drain line to the trap.
The trap can be constructed from a running tee of the same
diameter of the intake air pipe with EITHER a removable cap
attached to a 6-inch long pipe connected to the tee or the
External vent Trap Kit to help prevent contaminants from
entering the furnace. See Figure 51.
The External Vent Trap Kit accessory may be used as a trap for
the combustion air inlet pipe if a large amount of moisture must
be removed. The drain line may be connected to the same
drain as the furnace condensate and the evaporator coil
condensate line ONLY if the inlet air trap drain and the
evaporator coil drain empty into an open segment of pipe
above the drain, See Figure 12. When using the External Vent
Trap Kit, refer to those instructions for proper drain
connections.
The tee may also be connected to the intake air pipe on the
side of the casing. See Figure 51.
In any configuration, it will be necessary to add the equivalent
length of the tee (15 feet/5 M) to the Total Equivalent Vent
Length of the venting system.
440 01 4001 04 Specifications subject to change without notice. 43
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