Installation; Venting - Modine Manufacturing PD Installation And Service Manual

INSTALLATION

Venting

WARNING
1. Gas fired heating equipment must be vented - do not
operate unvented.
2. A built-in draft diverter is provided - additional external
draft diverters are not required or permitted.
3. Gas-fired heating equipment which has been improperly
vented, or which experiences a blocked vent condition may
have flue gasses accidentally spilled into the heated space.
See page 15 for specific information about the blocked vent
safety switch supplied on the unit.
4. Modine Manufacturing Company offers power exhausters
as an accessory. Power exhausters not supplied by Modine
Manufacturing Company are not permitted.
Note: A vent is the vertical passageway used to convey flue
gases from the unit or the vent connector to the outside
atmosphere. A vent connector is the pipe which connects the
unit to a vent or chimney. Vent connectors serving Category I
appliances shall not be connected into any portion of
mechanical draft systems operating under positive pressure.
General Venting Air Instructions
1. Installation of venting must conform with local building
codes, or in the absence of local codes, with the National
Fuel Gas Code, ANSI Z223.1 (NFPA 54) - Latest Edition. In
Canada, installation must be in accordance with CAN/CGA-
B149.1 for natural gas units and CAN/CGA-B149.2 for
propane units.
2. All units with single-stage controls are Category I. All units
with two-stage or modulating controls are Category II. The
installation of a Category II unit must conform to the
requirements from Table 5.1 in addition to those listed below.
3. From Table 25.1 or 26.1, select the size of vent pipe that fits
the flue outlet for the unit. Do not use a vent pipe smaller
than the size of the outlet or vent transition of the appliance.
The pipe should be suitable corrosion resistant material.
Follow the National Fuel Gas Code for minimum thickness
and composition of vent material. The minimum thickness for
connectors varies depending on the pipe diameter.
4. Limit length of horizontal runs to 75% of vertical height.
Install with a minimum upward slope from unit of 1/4 inch
per foot and suspend securely from overhead structure at
points no greater than 3 feet apart. For best venting, put
vertical vent as close to the unit as possible. Fasten
individual lengths of vent together with at least three
corrosion-resistant sheet-metal screws.
5. It is recommended that vent pipes be fitted with a tee with a
drip leg and a clean out cap to prevent moisture in the vent
pipe from entering the unit. The drip leg should be inspected
and cleaned out periodically during the heating season.
6. The National Fuel Gas Code requires a minimum clearance
of 6 inches from combustible materials for single wall vent
pipe. The minimum distance from combustible materials is
based on the combustible material surface not exceeding
160°F. Clearance from the vent pipe (or the top of the unit)
may be required to be greater than 6 inches if heat damage
other than fire (such as material distortion or discoloration)
could result.
7. Avoid venting through unheated space . When venting does
pass through an unheated space, insulate runs greater than
5 feet to minimize condensation. Inspect for leakage prior to
insulating and use insulation that is noncombustible with a
rating of not less than 350°F. Install a tee fitting at the low
point of the vent system and provide a drip leg with a clean
out cap as shown in Figure 6.1.
Table 5.1
ANSI Venting Requirements
Appliance
Category Description
I Negative vent pressure
Non-condensing
II Negative vent pressure
Condensing
III Positive vent pressure
Non-condensing
IV Positive vent pressure
Condensing
8. When the vent passes through a combustable wall or floor,
a metal thimble 4 inches greater than the vent diameter is
necessary. If there is 6 feet or more of vent pipe in the open
space between the appliance and where the vent pipe
passes through the wall or floor, the thimble need only be 2
inches greater than the diameter of the vent pipe. If a
thimble is not used, all combustible material must be cut
away to provide 6 inches of clearance. Any material used to
close the opening must be noncombustible.
9. Do NOT use dampers or other devices in the vent pipes.
10. Precautions must be taken to prevent degradation of
building materials by flue products.
11. The outlet of the vent should extend as shown in Figure 6.1
and Table 6.1 if the following conditions are met:
Vent diameter is less than 12 inches, vent is of double wall
construction and is a listed product, and the vent does not
terminate within 10 ' of a vertical wall or similar obstruction.
For vents that have a diameter of 12 inches or larger,
constructed of single wall, or terminate within 10 ' of a
vertical wall or similar obstruction, the vent pipe shall extend
at least 2 ' higher than any portion of a building within a
horizontal distance of 10 ' (refer to Figure 6.2).
12. Use a listed vent terminal to reduce downdrafts and
moisture in vent. A vent terminal that is very open will avoid
spillage at unit's diverter relief opening and tripping of the
blocked vent safety switch.
13. Check vent system to see that combustion products are
being vented properly. Operate unit for several minutes and
then pass a lighted match around the edge of the diverter
relief opening. If the flame is drawn into the opening, the
vent system is drawing properly. If not, make adjustments to
provide adequate draft (see figure 28.1).
14. For instructions on common venting refer to the National
Fuel Gas Code.
15. The vent must terminate no less than 5 ' above the vent
connector.
16. A unit located within an unoccupied attic or concealed space
shall not be vented with single wall vent pipe.
17. Single wall vent pipe must not pass through any attic, inside
wall, concealed space, or floor.
Venting
Requirements
Follow standard venting
requirements.
Condensate must be
drained.
Vent must be gastight.
Vent must be liquid and
gastight. Condensate must
be drained.
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