18
ALTA
Combi Installation, Operating & Service Instructions
110327-07 - 2/23
7
General Venting
(continued)
Model
Number
Vent/Air
Size in.
(mm)
Min
Equivalent
Length ft. (m)
Max
Equivalent
Length ft.
(m)
All Sizes
2 (60)
2.5 (0.76)
70 (21.3)*
3 (80)
2.5 (0.76)
135 (41.1)
See Table 3-3 for max vent de-rate.
*Reduced to 50 eq. ft. (15.2 m) for 200 combi LP
installations above 8,000 ft. (2,438 m).
Table 7-7: Vent and Air Sizing
1. Min and max lengths are calculated separately for
air and vent. For example, max length 135 ft. (41.1
m) means up to 135 ft. (41.1 m) air piping and up
to 135 ft. (41.1 m) vent piping.
Table 7-8: CPVC/PVC Fitting Equivalent Lengths
Fitting
Equivalent Length ft. (m)
2 in.
3 in.
90° Short Elbow
6.0 (1.8)
10 (3.0)
90° Sanitary Elbow
2.6 (0.8)
4.0 (1.2)
45° Elbow
1.5 (0.5)
2 (0.6)
3. Maximum length of flexible polypropylene venting
is reduced due to higher pressure drop. See
Table 7-10.
4. If using B-vent air chase, 1 ft. (0.30 m) B-vent
equals 1 equivalent ft. ( 0.30 m).
WARNING
Asphyxiation Hazard.
• Failure to vent this boiler in accordance with
these instructions could cause products of
combustion and/or carbon monoxide to enter
living space, resulting in severe personal injury,
death or substantial property damage.
• Vent installations shall be in accordance
with provisions of the National Fuel Gas Code,
ANSI Z223.1/NFPA 54, or "Natural Gas and
Propane Installation Code, CAN/CSA B149.1,
or applicable requirements of the local building
codes.
• This boiler requires a special venting system.
Use only CPVC, PVC, or polypropylene venting
systems listed in Tables 7-11 or 7-16.
• Thoroughly inspect finished vent and air
piping to ensure air-tightness and compliance
with provided instructions and code
requirements.
• Do not mix components from different venting
systems.
• Covering non-metallic vent pipe and fittings
with thermal insulation is prohibited.
• Follow all local codes for isolation of vent pipe
when passing through floors or walls.
• Do not use a barometric damper, draft hood,
or vent damper with this boiler.
• Do not connect any other appliance to vent
pipe or multiple boilers to a common vent pipe.
• Follow instructions in Section 5, Locating
Boiler, when removing a boiler from an existing
vent system.
• Failure to comply with any of the above
requirements could result in severe personal
injury, death or substantial property damage.
!
Vent and Air Sizing
2. If using 2 in. x 3 in. increaser, use max 12 in. (305
mm) of 2 in. pipe before increaser. For equivalent
length, count only 3 in. (80 mm) pipe starting from
increaser.
DuraVent
PolyPro
Centrotherm
InnoFlue
Selkirk
PolyFlue
2 in. (60 mm)
45° elbow
3 ft. (0.91 m) 3 ft. (0.91 m) 3.3 ft.
(1.0 m)
2 in. (60 mm)
90° or 87°
elbow
5 ft. (1.5 m)
5 ft. (1.5 m)
4.8 ft.
(1.5 m)
3 in. (80 mm)
45° elbow
3 ft. (0.91 m) 3 ft. (0.91 m) 3.6 ft.
(1.1 m)
3 in. (80 mm)
90° or 87°
elbow
7 ft. (2.1 m)
7 ft. (2.1 m)
7.2 ft.
(2.2 m)
Table 7-9: Rigid PolyPro Fitting Equivalent Lengths
Table 7-10: Flexible Polypropylene Equivalent
Length for 1 ft. (0.30 m) Measured Length
DuraVent
PolyPro
Flex
Centrotherm
InnoFlue
Flex
Selkirk
Polyflue Flex
2 in.
(60 mm)
2 ft.
(0.61 m)
2.5 ft.
(0.76 m)
2.5 ft.
(0.76 m)
3 in.
(80 mm)
2 ft.
(0.61 m)
2.3 ft.
(0.70 m)
2.3 ft.
(0.70 m)
WARNING
Asphyxiation Hazard.
2 in. (60 mm) max vent length reduced to 50.
eq. ft. (15.2 m) for 200 combi LP installations
above 8,000 ft. (2,438 m). Failure to comply
could cause unreliable operation at elevated
carbon monoxide (CO) level, resulting in severe
personal injury, death or substantial property
damage.
!
