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6 Installing a Vent
WARNING: CARBON MONOXIDE
Improper venting of the boiler can result in excessive levels
of carbon monoxide, which can lead to severe personal
injury or death. This boiler must be vented in accordance
with the "Venting of Equipment" section of the latest edition
of the ANSI Z223.1/NFPA 54 Natural Fuel Gas Code in the
USA and/or the "Venting systems and air supply for boilers"
section of the latest version of the CAN/CGA B149.1 Natural
Gas and Propane Installation Code in Canada, as well as all
applicable local building codes and regulations.
Follow all instructions and guidelines when venting the
boiler. Venting should be performed only by a licensed
professional.
The boiler must be properly vented to ensure a constant supply of clean intake air
and to ensure that exhaust air is properly removed from living areas. When venting
the boiler, follow these guidelines:
Do not install the boiler in areas with contaminated air (containing a
high level of dust, sawdust, sand, aerosols, or any other such airborne
contaminants), as contaminants can cause operational problems.
The warranty does not cover damage caused by contaminants in the
installation area. If you must install the boiler in an area with contaminated
air, use direct venting to supply air from outside the building. We
recommend regular filter cleaning and maintenance in these areas.
Keep the venting system as short and straight as possible.
Locate the boiler as close as possible to the vent termination.
Do not connect the boiler vent to a vent for any other gas boiler or vent
stack.
For horizontal runs, slope the horizontal section back towards the boiler at
a rate of 1/4" per foot (2° slope).
Create an airtight seal at each joint in the exhaust and intake air pipes from
the boiler collar to the vent termination.
To avoid moisture and frost build-up and to maintain clearances to
openings on adjacent homes, 45° elbows, 90° elbows, or tees may be
attached to the end of the termination vent pipe to direct the exhaust
fumes away from buildings, as long as the restrictions on total allowable
vent lengths, maximum number of elbows, and distances to air intake are
observed.
Do not store hazardous or flammable substances near the vent
termination.
If this boiler is to be installed in an area where snow is known to
accumulate, protect the vent termination from blockage.
Ensure that the vent termination is at least 12" (305mm) above ground, or
as required by local codes.
Support the vent pipe with hangers at regular intervals or as required by
local codes.
Exhaust and intake air pipes must be supported at least every 4 feet
(1.2m).
The vent for this appliance shall not terminate over public walkways;
or near soft vents or crawl space vents or where condensate or vapor
could create a nuisance or hazard or cause property damage; or where
condensate or vapor could cause damage or could be detrimental to the
operation of regulators, relief valves, or other equipment.
Singular Combi Boiler - BTC 439003301 B (2021/07)
6.1 Vent Type
All boilers are prepared at the factory to be direct vent (sealed combustion) boilers
that draw all of their required combustion air directly from outside the building.
Bosch recommends direct air vent installations whenever possible to avoid back
drafting cold air through the boiler. Bosch recommends direct air vent installations
when installing the boiler in your attic to get fresh air into the boiler. If you cannot
use a direct vent, ensure that an ample supply of make-up air is available in the
installation location. Bosch also recommends installing a new vent system with this
appliance. If reusing an existing vent system, thoroughly inspect it for punctures,
cracks, or blockages prior to connecting it to the boiler. When using non-direct
venting, you must provide two openings as specifi ed in the table on page 31.
6.1.1 Direct Venting
The boiler uses 2" or 3" diameter exhaust and 2" or 3" diameter intake air ducts. To
ensure the draw of air directly from and exhaust of air directly to the outside of the
building, create an airtight seal from the boiler collar to the vent termination.
Intake materials can be made of ABS, PVC, CPVC, PP, stainless steel, corrugated
aluminum or any other similar materials. If you use a corrugated material, ensure
that there is not inadvertent crimping of, or damage to, the intake air pipe.
When using direct venting, maintain the following venting clearances, as required
by ANSI Z21.10.3 and the National Fuel Gas Code, ANSI Z223.1/NFPA 54, and
CAN/CGA B149.1 Natural Gas and Propane Installation Code.
To use direct venting for the boiler:
Install the 2" vent directly. Ensure the vent is properly seated.
To install the 3" vent, reducer (3" to 2") must be used.
Install the reducer (3" to 2") vertically. If installed horizontally, water may
stagnate.
3" Elbow
Reducer (3" o 2")
Figure 28
Installation Instructions
3" PVC Pipe
2" PVC Pipe
2" Elbow
Condensation
pooling
| 29
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