74 Venting for Combustion Air
5.5 Measuring Vent Length
The maximum vent length when using 2 in exhaust
ducts is 65 ft (20 m). The maximum vent length
when using 3 in vent ducts is 150 ft (45 m). The
intake duct length may be identical to the exhaust
duct length. Maximum vent lengths reduce
according to the number of elbows used, as shown
in the following table:
Vent
Size
Maximum
Length
Maximum
# of Elbows Equivalent Length
2 in
65 ft
(19.5 m)
6
Reduce the
maximum vent
length accordingly
for each elbow used:
●
Each 90° elbow
equates to 8 linear
feet of vent
●
Each 45° elbow
equates to 4 linear
feet of vent
3 in
150 ft
(45 m)
8
Reduce the
maximum vent
length accordingly
for each elbow used:
●
Each 90° elbow
equates to 5 linear
feet of vent
●
Each 45° elbow
equates to 3 linear
feet of vent
Note
●
The Maximum Length does not
include any elbows.
●
The use of a PVC or polypropylene
termination kit counts as 5 linear feet
(1.5 m) of vent.
●
The use of a tee counts for the same
equivalent length as a 90° elbow for
the vent size.
●
The maximum vent lengths at high
altitudes are the same as shown in the
table above.
Centrotherm Innoflue® (Flexible)
(Certified to
UL1738 and ULCS636)
IFVL02xxx (2”) or IFVL03x xx (3”)
IFSFC02 or IFSFC03 (2” or 3” Rigid-to- Flex Male
Adapter)
ISEI0203 or ISIA0203 (2” t o 3” Increaser)
Hart & Cooley Polyflue™ SW (Rigid)
(Certified to
ULCS636)
2PF-xx (2”) or 3PF-xx (3”)
Z-Flex Z-DENS SW (Rigid)
(Certified to UL1738 and
ULCS636)
2ZDP___ (2” or 3”)
The following
stainless steel
vent components are
approved for use with this appliance:
Duravent FasNSeal® (Rigid)
(Certified to UL1738
and ULCS636)
FSA-PVC3 (3” PVC to FasN Seal Appliance Adapter)
FSxxxxx03 (3”)
Duravent FasNSeal® (Flexible)
(Certified to UL1738
and ULCS636)
FSASMM-PP-2 (2” PP-to-FasNSeal adapter)
FSFLEX-02 (2”)
Heat Fab Saf-T Vent® EZ Seal
9301PVC (3” PVC/CPVC Outlet Boiler Adapter)
93xx (3”)
Z-Flex Z Vent
2SVSTTA023 (2” x 3” Appliance Adapter)
2SVEPSCF030X (Straight Pipe)
2SVEEWCF0390 (90° Elbow)
2SVEEWCF0345 (45° Elbow)
Note
●
Only the vent pipe models listed
above are approved for use with this
appliance.
●
Proper appliance adapters must be
used when using polypropylene or
SS vent pipe.
●
Refer to the vent manufacturer’s
instructions for detailed installation
procedures and guidelines.
●
Do not use Schedule 40 or 80
polypropylene pipe used for water or
waste systems within the vent run.
Summary of Contents for NFC-250/175H
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