Use and Care Manual

6-583.4
A10. 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.
A11. Vent termination clearances must be maintained:
A12. Do NOT use dampers or other devices in the vent or
combustion air pipes.
A13. Precautions must be taken to prevent degradation of
building materials by flue products.
A14. Single wall vent pipe must not pass through any
unoccupied attic, inside wall, concealed space, or floor.
A15. 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.
A16. In addition to following these General Instructions,
specific instructions for Vertical Category I or Horizontal
Category III vent systems must also be followed. Table 7.2
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 feet,
the horizontal portion of the vent system cannot exceed
7.5 feet).
• 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
Table 7.2 - 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.
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 ➁
Table 7.1 - Vent Termination Clearances
➀ Do not terminate the vent directly above a gas meter or regulator.
➁ The vent must be at least 6" higher than anticipated snow depth.