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Finned copper tube gas boilers & water heaters – Boiler Manual
7
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3.
OPTION 3 — Side Wall Vent, Positive Pressure
Category IV (individual venting only) (page 11)
Combustion air is obtained from the space in which the unit is
installed. Vent system is certifi ed to UL 1738 for installations
in the United States, ULC S636 for installations in Canada.
Maximum equivalent length of vent and air piping must not
exceed 100 feet each.
To ensure proper boiler operation, boilers that use
room air must not be fi red at less than 33 % input. Th is
applies to OPTION 3 and OPTION 4 venting.
4.
OPTION 4 — Vertical Vent, Negative Pressure
Category II (common venting) (page 12)
Requires negative pressure in vent (natural draft ). Requires a
metal chimney system approved for Category II venting. Th is
method is required if common venting multiple XLF boilers.
All venting and combustion air material supplied by
installer. All venting materials must be approved for the
application. Consult the vent manufacturer’s product
literature.
Table 4
Category IV venting — vent pipe size
(Vent options 1, 2 or 3)
Input
MBH
Pipe diameter
in
mm
2500/3000
8
203
3500/4000
10
254
OPTION 1: DIRECT VENT
POSITIVE PRESSURE — CATEGORY IV
HORIZONTAL OR VERTICAL
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 Intake Air
Option instructions under the “Combustion air & ventilation”
section must be followed! Th e vent system must be sized per Table 4.
Horizontal direct vent systems
Figures 1 & 2
The vent materials used in horizontal vent systems must
be certifi ed to UL 1738 for installations in the United States, ULC
S636 for installations in Canada. Th e certifi ed vent terminal from
RBI must also be used.
Th e maximum equivalent length for the horizontal vent pipe is 100 ft ,
30.5 m. Each 90
o
elbow and the vent terminal are equal to 10 linear
ft , 3.0 m of pipe. If any part of a single wall metal vent system passes
through an unheated space, it must be insulated with insulation
rated for 400
o
F, 204
o
C. Structural penetrations must be made using
approved fi re-stops. For best results, horizontal vent systems should
be as short and straight as possible.
Th e vent system must be both gas tight and water-tight. 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. Th e 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
o
F, 204
o
C.
Horizontal vent systems shall terminate at least 4 ft , 1.2 m below, 4 ft ,
1.2 m horizontally from or 1 ft , 0.30 m above any door, window or
gravity air inlet into any building.
It must not terminate less than 4 ft , 1.2 m horizontally from, and in
no case above or below, unless a 4 ft , 1.2 m horizontal distance is
maintained, from electric meters, gas meters, regulators and relief
equipment; and not less than 7 ft, 2.1 m above adjacent public
walkway.
Canadian installations require a minimum of 6 ft,
18.3 m clearance from electric meters, gas meters,
regulators and relief equipment for compliance with
CAN B149.1.
Th e bott om of the vent terminal(s) shall be located at least 5 ft , 1.5 m
above the air intake terminal(s) unless there is a minimum 5 ft , 1.5 m
horizontal separation between them.
Avoid terminal locations likely to be aff ected by winds, snowdrift s,
people and pets. Protect building materials and vegetation from
degradation caused by the fl ue gases.
Vertical direct vent systems
Figure 3
(vent/air pipe equivalent lengths up to100 feet maximum)
If any part of a single wall metal vent system passes through an
unheated space, it must be insulated with insulation rated for 400
o
F,
204
o
C. Structural penetrations must be made using approved fi re-
stops.
An approved, nonrestrictive vent terminal must be used. Th e top of a
vertical vent system must extend at least 5.5 ft , 1.7 m above the roof
surface and maximum snow line that it passes through, 4 ft , 1.2 m
above the intake air terminal, see Figure 3.
In addition the vent system must conform to the dimensions shown
in Figure 3, page 9. Th e penetration point in the roof must be properly
fl ashed and sealed.
The vent system must be gas tight. All seams and joints in metal
pipes must be joined and sealed in accordance with the vent system
manufacturer’s instructions.
Combination direct vent systems
Figure 4
(vent/air pipe equivalent lengths up to100 feet maximum)
The boiler/water heater can be vented vertically with the
intake air piped horizontally through an outside wall. Follow
the instructions in the Intake Air Option — Horizontal
Guidelines on page 6. Also follow the general instructions
in the “Combustion Air & Ventilation” and “General Venting
Guidelines” sections.
