Modine Manufacturing HD Series Installation And Service Manual page 10

InsTAllATIon - venTIng
section C – Horizontal, Category III vent system
Installation
C1. This section applies to horizontally vented Category III
vent systems and is in addition to "Section A – General
Instructions – All Units".
C2. All heaters that are horizontally vented perform as a
Category III appliance. Category III venting has special
venting requirements as follows:
• All residential, horizontally vented Category III heaters
must be vented with an agency certified (ul1738)
Category III venting system. Agency certified
Category III venting systems are available from your
local vent pipe distributor. Follow the agency certified
Category III vent manufacturer's instructions for
installation.
• For commercial and industrial horizontally vented
heaters you may use either agency certified Category
III venting systems as noted above, or single wall
galvanized or stainless steel vent pipe. For single
wall vent systems, one continuous section of double
wall vent pipe may be used within the vent system to
pass through the wall to the listed terminal. Refer to
instruction A10 in "Section A – General Instructions – All
Units" for attaching double wall pipe to single wall pipe.
If single wall vent pipe is used, all seams and joints
must be sealed with metallic tape or silastic suitable for
temperatures up to 400°F. Wrap the tape two full turns
around the vent pipe.
C3. All horizontal Category III vents must be terminated with a
listed vent cap. The cap must terminate a minimum distance
from the external wall, as summarized in Table 10.1.
Table 10.1 - minimum length Between external
Wall and vent
model
size Application
30-75 Residential & Commercial
100, 125 Residential
100, 125 Commercial
➀ Refer to Figure 10.2 and 10.3.
C4. The vent must be supported as shown in Figure 10.1.
figure 10.1 - exhaust vent Construction Through
Combustible Walls and support Bracket
METAL
SLEEVE
2" MIN.
VENT PIPE
DIAMETER
METAL FACE
METAL
SLEEVE
2" MIN.
1"
C5. When condensation may be a problem, the vent system shall
not terminate over public walkways or over an area where
condensate or vapor could create a nuisance or hazard or
could be detrimental to the operation of regulators, relief
openings, or other equipment.
C6. The venting system must be exclusive to a single unit, and
no other unit is allowed to be vented into it.
10
min. length
A ➀
11"
12"
24"
FIBER GLASS
INSULATION
MIN. 2"
PLATE
1"
9"
VENT TERMINATION
45 SUPPORT BRACKET
9" (where required)
(Make from 1" x 1" steel angle)
C7. When vented horizontally, maintain a 1/4" per foot rise away
from the heater and place a drip leg with clean out near the
unit as shown in Figure 10.2. Where local authorities have
jurisdiction, a 1/4" per foot downward slope is acceptable
with a drip leg and clean out near the exit of the vent as
shown in Figure 10.3, or allow the condensate to drip out the
end.
figure 10.2 - Horizontal Category III venting with
upward pitch
A
6" Above
snow Listed Thimble
grade
1 / " Slope per foot up towards termination
4
figure 10.3 - Horizontal Category III venting with
downward pitch (with drip leg)
A
Listed
Thimble
1
/ " Slope per foot down towards termination
4
C8. For a vent termination located under an eave, the distance
of the overhang must not exceed 24". The clearance to
combustibles above the exterior vent must be maintained
at a minimum of 12". Consult the National Fuel Gas Code
for additional requirements for eaves that have ventilation
openings.
C9. Once venting is complete, proceed to the section titled
"Installation – Gas Connections".
6-583.6
Listed Terminal
Drip leg / Clean out cap
3' Min
30' Max
Listed Terminal
Drip leg / Clean out cap
3' Min
30' Max