Installation, Operation and Maintenance Instructions Manual

Mighty Stack Water Heater
Page 7
• Avoid using an oversized vent pipe or using
extremely long runs of the pipe. This may cause
excessive cooling and condensation of flue gases.
Figure 5. Chimney Venting.
1K. Vertical Venting – Category I
This unit can be vented into a masonry chimney,
provided several conditions are met (see Figure 5.)
• The chimney must have an appropriate tile
lining. The lining should be the correct size,
should be constructed correctly, and must be
clean.
• Check the chimney passage way to be sure that it
is clear and free of obstructions.
• If the chimney must be rebuilt, follow nationally-
recognized standards. (See the National Building
Code or ANSI/NFPA 211).
• 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 mm per 50 mm). The vent connector
must be strong enough to support the weight of the
The information in Table 5 is not applicable in
installations where exhaust fans or blowers of any
type are used. Such installations must be designed by
qualified engineers.
If a blower or fan is used to supply air to the
water heater room, the installer should make sure it
does not create drafts which could cause nuisance
shutdowns. If a blower is necessary to provide
adequate combustion air to the water heater, a switch
or equivalent must be wired into the water heater
control circuit to prevent the water heater from firing
unless the blower is operating.
The water heater must be protected from any
source of corrosive chemical fumes including those
emitted by trichlorethylene, perchlorethylene,
chlorine, etc.
1J. General Venting Instructions
WARNING
This water heater must be vented in accordance
with Part 7, Venting of Equipment, of the latest
edition of the National Fuel Gas code, ANSI Z223.1
and all applicable local building codes. In Canada,
follow CAN/CGA B149 Installation codes. Improper
venting of this appliance can result in excessive
levels of carbon monoxide which can result in
severe personal injury or death!
Here are some general rules to follow when
venting this unit:
• Place the water heater as close as possible to the
vent or chimney.
• The vent collar on the water heater must be
fastened directly to an unobstructed vent pipe.
Use rustproof sheet metal screws no longer than
1/2" (13 mm).
• Do not weld the vent pipe to the water heater
collar. The weight of the stack must not rest on
the water heater. The top of the water heater
must be easily removable for normal service and
inspection of the unit.
• The water heater vent must not be connected to a
fireplace, wood stove or other equipment which
burns solid fuel.
• Avoid terminating the water heater vent near any
air-conditioning or air-supply fans. These fans
can pick up the exhaust flue products from the
water heater and return them to the building.
This can create a health hazard.