Modine Manufacturing PTX Installation And Service Manual page 9

INSTALLATION - VENTING
Section B – Vertical Vent Only, Category I Vent
System Venting Instructions
B1. This section applies to vertically vented Category I
vent systems and is in addition to "Section A - General
Instructions - All Units".
B2. Vertical vent systems terminate vertically, and must be
sized in accordance with the National Fuel Gas Code, ANSI
Z223.1 (NFPA 54) - latest edition.
B3. The horizontal portion of the vent run cannot exceed 75%
of the vertical rise (Example: If the vent height is 10', the
horizontal portion of the vent system cannot exceed
7.5').
B4. It is recommended to install a tee with drip leg and clean out
cap as shown in Figure 9.1.
B5. The vent terminates a minimum of 5' above the vent
connector on the unit.
B6. All vertically vented heaters that are Category I must be
connected to a vent complying with a recognized standard,
with a material acceptable to the authority having jurisdiction.
Venting into a masonry chimney is not permitted. Refer to
the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) - latest
edition for instructions on common venting.
B7. Use a listed vent terminal to reduce down drafts and
moisture in the vent.
B8. Double wall vent pipe is recommended, although single wall
can be used if the requirements of the National Fuel Gas
Code are followed.
B9. Vertical vents must terminate a minimum horizontal and
vertical distance from roof lines and adjacent walls or
obstructions. These minimum distances are outlined as
follows (based on National Fuel Gas Code requirements for
vents with diameters less than 12"):
• For double wall vent pipe and 8' or greater horizontal
distance to any vertical wall or similar obstruction, the
vent must terminate above the roof in accordance with
Figure 9.1 and Table 9.1.
• For double wall vent pipe and less than 8' horizontal
distance to any vertical wall or similar obstruction, the vent
must terminate at least 2' above the highest point where it
passes through a roof of a building and at least 2' higher
than any portion of a building within a horizontal distance of
10' (see Figure 9.1).
• For single wall vent pipe and 10' or greater horizontal
distance to any portion of a building, the vent must
terminate at least 2' above the highest point where it passes
through a roof of a building and at least 2' higher than any
portion of a building within a horizontal distance
of 10'.
• For single wall vent pipe and less than 10' horizontal
distance to any portion of a building, the vent must
terminate at least 2' higher than any portion of that building.
Table 9.1 - Minimum Height from Roof to Lowest
Discharge Opening
Rise X (in)
0-6
6-7
7-8
8-9
9-10
10-11
11-12
12-14
14-16
16-18
18-20
20-21
Size according to expected snow depth.
j
Figure 9.1 - Vertical Category I Vent System
X
ROOF PITCH IS:
X / 12
12
USE LISTED THIMBLE
THROUGH ROOF AND
CEILING
BACK VIEW
6-534.1
Roof Pitch Min Height H (ft) j
Flat to 6/12 1.00
6/12 to 7/12 1.25
7/12 to 8/12 1.50
8/12 to 9/12 2.00
9/12 to 10/12 2.50
10/12 to 11/12 3.25
11/12 to 12/12 4.00
12/12 to 14/12 5.00
14/12 to 16/12 6.00
16/12 to 18/12 7.00
18/12 to 20/12 7.50
20/12 to 21/12 8.00
LISTED TERMINAL
"H" MIN*
ROOF FLASHING
4" MIN
EXHAUST
TEE WITH DRIP LEG
AND CLEANOUT CAP
(SLOPE 1/4" PER
FOOT DOWNWARD
TOWARD DRIP LEG)
12" MIN
RECOMMENDED
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