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Vent Pipe IVlaterial
Vent and combustion air pipe and fittings must be
CARBON MONOXIDE
POiSONiNG HAZARD
.
2.
Seal any unused openings in the vent-
ing system
inspect the venting system for proper
size and horizontal
pitch, as required
in the National
Fuel Gas Code, ANSi
Z223.1 or the CAN/CGA
B149 Instal-
lation Codes and these
instructions.
Determine
that there
is no blockage
or restriction,
leakage, corrosion
and
other deficiencies
which could cause
an unsafe condition.
3.
So far as is practical,
close all build-
ing doors
and windows and all doors
between
the
space
in which
the
appliance(s)
connected to the venting
system are located and other spaces
of the building.
4.
Follow the lighting
instructions.
Place
the appliance being inspected in opera-
tion. Adjust thermostat
so appliance
shall operate continuously.
5.
Turn on clothes dryers and any other
appliance
not connected
to the vent-
ing system. Turn on any exhaust fans,
such as range
hoods and bathroom
exhausts, so they shall operate at maxi-
mum speed. Do not operate a summer
exhaust fan.
.
7.
Close fireplace
dampers.
Test
for
spillage
from
draft
hood
equipped
appliance
at the draft hood
relief opening after 5 minutes of main
burner
operation.
Use the flame of a
match or candle.
one of the following materials and must conform
to the indicated ANSl/ASTM
standards:
Material
Standard
Schedule 40 PVC
D1785
PVC-DWV
D2665
SDR-21
D2241
& SDR-26
ABS- DWV
D2661
Schedule 40 ABS
F628
Foam/Cellular
Core PVC F891
*In Canada, all plastic vent pipe must be certified
to ULC S636.
Cement
and primer
must conform
to ATSM
Standard D2564 for PVC and Standard
D2235
for ABS. When joining PVC piping to ABS, use
PVC solvent cement. (See procedure specified
in ASTM Standard
D3138.)
Vent Pipe Length and Diameter
In order for the furnace
to operate
properly,
the combustion air and vent piping must not be
excessively restrictive. To ensure this use Table
5, which indicates the maximum allowable pip-
ing length for a furnace of specified
input rate,
when installed with piping of selected diameter
and number of elbows. This table applies to the
length and number of elbows for each pipe. To
use the table, the furnace input rate, the center-
line length and the number of elbows on each
pipe must be known.
Choose the diameter for
which the tabulated length is equal to or greater
than required.
Proper use of the table is illustrated by the fol-
lowing example:
.
.
if improper venting is observed during
any of the above tests, the venting sys-
tem must be corrected
in accordance
with the National Fuel Gas Code, ANSI
Z223.1/NFPA
54 and/or
CSA B149.1,
Natural Gas and Propane
Installation
Codes.
After it has been determined
that each
appliance
connected
to the venting
system properly vents when tested
as
outlined above, return doors, windows,
exhaust fans, fireplace
dampers
and
any other gas
burning
appliance
to
their previous conditions
of use.
Example:
An 80,000 Btu/h furnace is to be installed in a
"one-pipe" system with 40 feet of vent piping.
There are a total of four long radius 90-degree
elbows used in the vent, including the one exterior
to the building.
Solution:
For this particular installation, the equivalent vent
length must be calculated. This equivalent vent
length will then be compared to the maximum
allowable vent length given in Table 5. Then, the
diameter of the piping can be chosen for which the
equivalent vent length is less than the maximum
18
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