Instructions / Assembly

6-583.8
diameter is necessary. If there is 6' 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" greater than the diameter of the vent pipe. If a
thimble is not used, all combustible material must be cut
away to provide 6" of clearance. Where authorities have
jurisdiction, type B vent may be used for the last section
of vent pipe to maintain clearance to combustibles while
passing through wall or floor (see Figure 6.1). Any material
used to close the opening must be noncombustible.
A11. The following are general instructions for double wall
(type B) terminal pipe installation:
How to attach a single wall vent terminal to double wall
(type B) vent pipe:
1. Look for the “flow” arrow on the vent pipe.
2. Slide the vent terminal inside the exhaust end of the
double wall vent pipe.
3. Drill 3 holes through the pipe and the vent terminal.
Using 3/4" long sheet metal screws, attach the cap to
the pipe. Do not over tighten.
How to connect a single wall vent system to double
wall (type B) vent pipe:
1. Slide the single wall pipe inside the inner wall of the
double wall pipe.
2. Drill 3 holes through both walls of the single and double
wall vent pipes. Using 3/4" sheet metal screws, attach
the two pieces of pipe. Do not over tighten.
3. The gap between the single and double wall pipe must
be sealed, but it is not necessary to fill the full volume
of the annular area. To seal, run a large bead of 400°F
silastic around the gap.
A12. Vent termination clearances must be maintained:
A13. Do NOT use dampers or other devices in the vent or
combustion air pipes.
A14. Precautions must be taken to prevent degradation of
building materials by flue products.
A15. Single wall vent pipe must not pass through any
unoccupied attic, inside wall, concealed space, or floor.
A16. Uninsulated single wall vent pipe must not be used
outdoors for venting appliances in regions where the 99%
winter design temperature is below 32°F.
A17. The vent terminal must be:
A18. In addition to following these general instructions, specific
instructions for Vertical Category I or Horizontal Category III
vent systems must also be followed. Table 7.3 outlines the
differences:
Note: Vent connectors serving Category I appliances shall not be connected into
any portion of mechanical draft systems operating under positive pressure.
Vertical Category I Vent System Determination
• Verticalventsystemsterminatevertically(up).
• 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').
• Theventterminatesaminimumof5’abovetheventconnector
on the unit.
• IftheventsystemtobeinstalledmeetsALLthesecriteria
(an example is shown in Figure 9.1), proceed to “Section B –
Vertical Vent System Installation”. For all other cases, proceed
to the next section for Horizontal Category III Vent System
Determination:
Horizontal Category III Vent System Determination
•Horizontalventsystemsterminatehorizontally(sideways).
•Aventsystemthatterminatesverticallybuthasahorizontal
run that exceeds 75% of the vertical rise is considered
horizontal.
Horizontal vent configurations are Category III. For residential
installations, this requires the use of an agency approved
(UL1738) Category III vent system. Additional requirements,
including those for commercial and industrial installations are
covered in “Section C – Horizontal, Category III Vent System
Installation”.
7
INSTALLATION - VENTING
Minimum Clearances for
Structure Vent Terminal Location
Forced air inlet within 10 feet 3 feet above
Combustion air inlet of another
appliance 6 feet all directions
Door, window, gravity air inlet, 4 feet horizontal and below
or any building opening 1 foot above
Electric meter, gas meter, gas 4 feet horizontal (U.S.)
regulator, and relief equipment ➀ 6 feet horizontal (Canada)
Gas regulator ➀ 3 feet horizontal (U.S.)
6 feet horizontal (Canada)
Adjoining building or parapet wall 6 feet all directions
Adjacent public walkways 7 feet all directions
Grade (ground level) 3 feet above
Table 7.1 - Vent Termination Clearances
➀ Do not terminate the vent directly above a gas meter or regulator.
Table 7.3 - ANSI Unit Heater Venting Requirements
Category Description Venting Requirements
I Negative vent pressure Follow standard
Non-condensing venting requirements.
II Negative vent pressure Condensate must
Condensing be drained.
III Positive vent pressure Vent must be gas tight.
Non-condensing
IV Positive vent pressure Vent must be liquid and
Condensing gastight. Condensate
must be drained.
Table 7.2 - Vent Terminals
Model Size Modine PN Other Listed Terminals
30-75 5H0722850005 Gary Steel 1092
100-125 5H0722850001 Gary Steel 1092