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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 Fig. 52.
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.
ADDITIONAL
INFORMATION
FOR
POLYPROPYLENE
VENTING
SYSTEMS
Polypropylene
venting
systems
include
flexible
vent
pipe.
These
flexible
vent
pipes
have
a different
equivalent
vent
length
than straight sections
of PVC/ABS
DWV vent pipe. Be
sure to make
the appropriate
deductions
from
the Maximum
Equivalent
Vent Length
(MEVL),
or additions
to the Total
Equivalent
Vent Length
(TEVL),
when applying
flexible
vent
pipes
in
polypropylene
venting
systems.
See
the
polypropylene
vent
system
manufacturer's
installation
instructions
for details.
When
using
metric-sized
venting
systems,
use
these
equivalencies
for obtaining
the proper
MEVL from the Tables:
Use 2" Vent Tables for 60 mm (o.d.) vent systems
Use 3" Vent Tables for 80 mm (o.d.) vent systems
Use 4" Vent Tables for 100 mm (o.d.) vent systems
The measured
length
of pipe used in a single or 2-pipe
termination
is included
in the total vent
length.
Include
deductions
from the
Maximum
Equivalent
Vent
Length
(MEVL)
contained
in the
Venting
Tables
for
elbows
and
flexible
vent
pipe.
Factory
accessory
concentric
vent terminations
or pipe lengths
and elbows
used for "standard"
vent terminations
do not require
a deduction
from the Maximum
Equivalent
Vent Length.
See vent termination
figures
associated
with Table 15.
NOTE:
Polypropylene
venting
systems
MAY require
additional
deductions
from
the MEVL,
or additions
to the TEVL,
for vent
terminations
and
flexible
pipe
sections.
See
the polypropylene
venting
system
manufacturer's
instructions
for
details
on
equivalent
lengths
of vent
terminations
and
flexible
vent pipes,
and for calculating
total vent lengths.
To calculate
the Total
Equivalent
Vent
Length
(TEVL)
of the
venting
system:
1. Measure
the individual
distance
from the furnace
to the ter-
mination
for each pipe.
2. Count the number
of elbows
for each pipe.
3. For each pipe, multiply
the number
of elbows
by the equi-
valent
length
for the type of elbow used.
Record
the equi-
valent length
of all the elbows for each pipe.
4. If a Tee is used
on the termination,
record
the equivalent
length
of the Tee used.
5. Calculate
Total Equivalent
Vent Length
by adding
the equi-
valent lengths
of the fittings
to the lengths
of the individual
vent and combustion
air pipes.
6. When
using
polypropylene
venting
systems
with
flexible
vent pipes, perform
adjustments
for the equivalent
length
of
the
flexible
vent
pipe
to the calculated
total
equivalent
venting
system
length.
See the polypropylene
vent system
manufacturer's
instructions
for details.
7. Select
a diameter
of vent pipe from Tables
15 and 17 and
note the Maximum
Equivalent
Vent Length (MEVL)
shown
for that
application
for that
specific
furnace
input
size.
Compare
the Total Equivalent
Vent Length
(TEVL)
to the
MEVL:
8. If the Total
Equivalent
Vent
Length
is shorter
than
the
Maximum
Equivalent
Vent Length
for the diameter
of pipe
chosen,
then that diameter
of pipe selected
may be used.
9. If the
Total
Vent
Length
is longer
than
the
Maximum
Equivalent
Vent
Length
for the diameter
of pipe chosen,
that
diameter
pipe
MAY
NOT
be
used
for venting
the
furnace.
Try the next larger diameter
pipe.
NOTE:
If the calculated
Total Equivalent
Vent Lengths
results in
different
diameter
pipes for the vent and combustion
air, select the
larger diameter
for both pipes.
NOTE:
If the Maximum
Vent Length
for diameter
of the pipe
selected
is longer
than
the measured
length
and the equivalent
length
of all the
fittings
and terminations
(TEVL),
recalculate
Total Equivalent
Vent Length
using
the next smaller
diameter.
If
the
Maximum
Equivalent
Vent
Length
is still
longer
than
the
longer
TEVL
of the vent pipe or combustion
air pipe,
then that
diameter
of pipe selected
may be used.
When
installing
vent systems
pipe lengths
of 10 ft. (3 M), use the
smallest
allowable
pipe diameter.
Using
a pipe size greater
than
required
for short venting
systems
may result in loss of efficiency,
incomplete
combustion,
flame disturbance,
or flame sense lockout.
For vent systems
longer
than 10 ft. (3 M), any larger diameter
vent
pipe shown
in Table 15 or 17 FOR
THAT
SIZE
FURNACE
may
be used.
Combustion
Air and Vent Piping
Insulation
Guidelines
NOTE:
Use closed cell, neoprene
insulation
or equivalent.
The vent pipe may pass through
unconditioned
areas. The amount
of exposed
pipe allowed
is shown
in Table 14.
1. Using winter design
temperature
(used in load calculations),
find appropriate
temperature
for your
application
and fur-
nace model.
2. Determine
the amount
of total and exposed
vent pipe.
3. Determine
required
insulation
thickness
for exposed
pipe
length(s).
4. When combustion
air inlet piping
is installed
above
a sus-
pended
ceiling,
the pipe MUST
be insulated
with moisture
resistant
insulation
such
as Armaflex
or other
equivalent
type of insulation.
5. Insulate
combustion
air inlet piping when
run in warm, hu-
mid spaces.
6. Install
the insulation
per the insulation
manufacturer's
in-
stallation
instructions.
NOTE:
Pipe length
(ft. / M) specified
for maximum
pipe lengths
located
in unconditioned
spaces
cannot exceed
total allowable
pipe
length
as calculated
from Table 15 or 17.
Configure
the Furnace
CARBON
MONOXIDE
POISONING
HAZARD
Failure
to follow
this
warning
could
result
in personal
iniury or death.
To route the vent pipe and combustion
air pipe through
the
furnace,
the manufacturer
supplied
kit must be used. Failure
to properly
seal the blower
compartment
from
the furnace
vestibule
could result in the circulation
of carbon monoxide
throughout
the structure.
The vent pipe and combustion
air
pipe must be a continuous
pipe while
passing
through
the
blower
compartment.
Seals
supplied
in this kit must
be
installed
per
the
instructions
provided.
Follow
all
procedures
outlined
in these instructions.
39
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