Use and Care Manual

6-580.15
7
A10. When the vent passes through a combustible INTERIOR
wall or floor, a metal thimble 4" greater than the vent
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. Seal all seams and joints of un-gasketed single wall pipe
with metal tape or Silastic suitable for temperatures up to
400°F. Wrap the tape 2 full turns around the vent pipe.
One continuous section of double wall vent pipe may be
used within the vent system to pass through the wall to the
listed vent cap. Refer to instruction A12 in “Section A –
General Instructions – All Units” for attaching double wall
pipe to single wall pipe.
A12. 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 a
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 2 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.
A13. Vent termination clearances must be maintained:
A14. Do NOT vent this appliance into a masonry chimney.
A15. Do NOT use dampers or other devices in the vent or
combustion air pipes.
INSTALLATION - VENTING
 Do not terminate the vent directly above a gas meter or regulator.
Table 7.1 - Vent Termination Clearances
A16. The venting system must be exclusive to a single
appliance and no other appliance is allowed to be vented
into it.
A17. Precautions must be taken to prevent degradation of
building materials by flue products.
A18. Single wall vent pipe must not pass through any
unoccupied attic, inside wall, concealed space, or floor.
A19. 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.
A20. The vent terminal must be:
A21. If left hand (facing front of heater with air blowing in face)
power exhauster discharge is desired, the power
exhauster may be rotated 180°. To do this, remove the
screws in the vent collar, rotate the power exhauster, then
replace the screws.
A22. In addition to following these general instructions, specific
instructions for Vertical Category I or Horizontal Category
III vent systems must also be followed. The following
outlines the differences:
Minimum Clearances for
Structure Vent Terminal Location
Forced air inlet within 10' 3' above
Combustion air inlet of another
appliance 6' all directions
Door, window, gravity air inlet, 4' horizontal and below
or any building opening 1' above
Electric meter, gas meter, gas 4' horizontal (U.S.)
regulator, and relief equipment  6' horizontal (Canada)
Gas regulator
3' horizontal (U.S.)
6' horizontal (Canada)
Adjoining building or parapet wall 6' all directions
Adjacent public walkways 7' all directions
Grade (ground level) 3' above

Vertical Category I Vent
• Vertical vent systems terminate vertically (up) (an example
is shown in Figure 8.1).
• 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 8.1), 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
• Horizontal vent systems terminate horizontally (sideways)
(an example is shown in Figure 9.2).
• 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. Additional
requirements are covered in “Section C - Horizontal
Category III Vent System Installation”.
Table 7.3 - ANSI Unit Heater Venting Requirements
Category Description Venting Requirements
I
Negative vent pressure
Non-condensing
Follow standard venting
requirements.
II
Negative vent pressure
Condensing
Condensate must be
drained.
III
Positive vent pressure
Non-condensing
Vent must be gas tight.
IV
Positive vent pressure
Condensing
Vent must be liquid and
gas tight. Condensate
must be drained.
Note: Vent connectors serving Category I appliances shall not be connected
into any portion of mechanical draft systems operating under positive pressure.
Table 7.2 - Vent Terminals
Model Size Modine PN
150-200 5H0722850004
250-400 5H0722850002