LAARS Mighty-Stack TL80-199 - Installation, Operation and Maintenance Instructions - Manual (Page 8)

LAARS Heating Systems Company
Page 8
• When the water heater and a boiler are to be
connected to the same chimney, each unit must
have its own vent connector. The two connectors
must enter the chimney at least 6" (152 mm)
apart.
(a) Vent Connections
Use type B double wall or type C single wall gas
vent pipe (26 gauge, minimum thickness) from the
water heater to the chimney. Laars recommends
installation of a riser with a minimum of 12" (305
mm) height above the water heater. The vent system
should be sloped up toward the chimney at a rate of 1/
4" per foot (1 cm per 50 cm). The vent connector must
be strong enough to support the weight of the material
used. This will maintain the clearances and prevent
physical damage and separation of the joints.
NOTE: Always provide a minimum clearance of
6 inches (152 mm) between a Type C vent pipe and
any combustible materials.
Warning
Single-wall vent pipe must never pass through
interior walls, or through floors or ceilings! Failure to
comply with this warning could result in a fire,
causing property damage, personal injury, or death!
When installing the vent system, all applicable
national and local codes must be followed! If you
install thimbles, firestops or other protective devices,
and they penetrate any combustible or noncombustible
construction, be sure to follow all applicable national
and local codes.
If a vertical vent is installed, follow the code
requirements for Category 1, Fan Assisted
Appliances. Follow the requirements as indicated in
the latest edition of ANSI Z223.1/NFPA 54. See
“Sizing of Category I Venting Systems” and
“Appendix G.” In Canada, follow the instructions in
the CAN/CGA-B149 installation code.
An unused chimney can be used as a raceway for
a single-wall vent pipe (see Figure 7). Never run a
vent pipe through a flue that has another appliance
attached to it.
(b) Vent Termination
A listed vent terminal must complete the vertical
run where it exits the chimney. This must be designed
for the type of pipe being used. The vent pipe must
extend at least 3 feet (1 m) above the highest point
where it passes through the roof. In addition, the vent
cap must be at least 2 feet (0.6 m) higher than any part
of a building within a horizontal distance of 10 feet
(3m). Clearance to any combustible materials must be
maintained as listed (see Figure 8).
1L. Horizontal Venting – Category III
When a vent system is horizontal or cannot meet
the requirements of Category I, it can develop positive
pressure. This type of system must be installed in
accordance with the instructions in this section, and
with the instructions supplied by the vent
manufacturer.
(a) Vent Connections
The vent system must be gas tight. All seams
and joints must be sealed with silicone sealant or
adhesive tape having a minimum temperature rating of
400°F (204°C). (See Table 6 for a list of approved
sealing materials.)
Figure 7. Vertical Venting.
Figure 6. Chimney Venting.