Finned copper tube gas boilers & water heaters – Boiler Manual
10
VERTICAL/CHIMNEY VENTING
The LCD is listed as a Category I appliance when vented vertically
into a metal chimney system or properly sized masonry chimney,
Figures 1, 2, 6 & 7. The chimney must provide a negative pressure
of
0.01 to
0.08 in
,
.25 to 2.0 mm
WC at the boiler/water heater
flue collar with the unit running at full load. A barometric damper
must be installed between the flue collar and the vent connector.
Approved thimbles and fire-stops must be used when combustible
construction is penetrated.
If an appliance using any type of a mechanical draft
system operating under positive pressure is connected
to a chimney flue, never connect any other appliances
to this flue. Doing so can result in excessive levels of
carbon monoxide which can cause severe personal
injury or death!
Chimney Inspection & Sizing
A thorough inspection of the masonry chimney must be
performed to ensure that the chimney is clean, properly constructed,
lined and sized. Exterior masonry chimneys should not be used
unless properly lined to prevent condensation and draft problems.
Table 5 lists the equivalent breeching and flue sizes required for
the boiler/water heater. When more than one appliance is connected
to the same chimney flue, the flue must be large enough to safely
vent the combined output of all of the appliances.
Table 5 Equivalent Breeching & Chimney Size (Category I)
Model Size
Pipe Diameter
in
mm
400
6
152
600
7
178
750
8
203
1050
10
254
1200 - 1480
12
305
1650 - 2300
14
356
Note: These sizes are based on 20 ft,
6.1 m
chimney height.
Vent Connections
Locate the boiler/water heater as close to the chimney as possible.
Use the shortest, straightest vent connector possible for the
installation. If horizontal runs exceed
5 ft
,
1.5 m
they must be
supported at
3 ft
,
0.9 m
intervals with overhead hangers. Use a
type B, single wall stainless or single wall galvanized steel vent pipe
the same diameter as the flue collar to connect the boiler/water
heater to a masonry chimney. When using an approved metal
chimney system use the appropriate vent connector. The vent
connector should be sloped up toward the chimney at a minimum
rate of
1/4 in/ft
,
20 mm/m
. On masonry chimneys the connector
must terminate flush with the inside of the chimney flue, Figure 2.
Fasten each single wall vent connection with at least 3 corrosion
resistant sheet metal screws.
Never install a vent pipe having a diameter different
than that of the boiler/water heater flue collar. Failure
to comply with this warning can result in excessive
levels of carbon monoxide which can cause severe
personal injury or death.
Always provide a minimum clearance of
6 in
,
152
mm
between
single wall vent pipe and any combustible materials. Type B1 vent
may be used, clearance between it and any combustible material
must be as listed.
Failure to maintain minimum clearances between vent
connectors and any combustible material can result
in a fire causing extensive property damage, severe
personal injury or death!
DIRECT VENT, POSITIVE PRESSURE,
CATEGORY III
In this configuration the boiler/water heater blower is used to push
the flue products to the outdoors while drawing combustion air
from the outdoors. The equivalent length of the vent and combustion
air systems
must not
exceed
35 ft
,
10.7 m
for each. The Intake
Air Option instructions under the “COMBUSTION AIR &
VENTILATION” section must be followed! The vent system flue
pipe diameter must be sized per Table 5a.
Horizontal Direct Vent Systems - Figures 4 & 5
The vent materials used in horizontal vent systems must be certified
to UL 1738 for installations in the United States, ULC S636 for
installations in Canada. The certified vent terminal from RBI must
also be used.
The maximum equivalent length for the horizontal vent and
combustion air pipes is
35 ft
,
10.8 m
for each. Each 90° elbow
and the intake air and vent terminals are equal to
10 ft
,
3.1 m
of
straight pipe. To maximize the performance of single wall sheet
metal vent systems locate 90° elbows as far from the boiler as possible
and from one another. For best results, horizontal vent systems
should be as straight as possible.
The vent system must be both gas tight and watertight. All seams
and joints in metal pipes must be joined and sealed in accordance
with the vent system manufacturer’s instructions.
When horizontal vent runs exceed
5 ft
,
1.5 m
they must be supported
at
3 ft
,
0.9 m
intervals with overhead hangers. The vent system
must be pitched down, toward the vent terminal,
1/4 in/ft
,
20 mm/m
. If any part of a single wall metal vent system passes
through an unheated space it must be insulated with insulation rated
for
400°f
,
204°C
.
