Installing A Common Vent System; About The Common Vent System - Navien NFC-250/175H Installation Manual

9. Installing a Common Vent System

9.1 About the Common Vent
System
The Navien Common Vent System* provides an easy
way to install the vent system for an NFC-H boiler
unit and up to 7 NPE water heater units. By sharing
the main intake and exhaust vent pipes, effective
system venting is available with less venting
materials and minimal number of penetrations on
the walls or roofing.
* Independently tested and approved by CSA
Read all safety messages and carefully follow the
guidelines in this manual when installing a common
vent system for the NFC-H boiler units.
WARNING
Improper venting of the boiler units can result
in excessive levels of carbon monoxide, which
can lead to severe personal injury or death. The
boiler units 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, as
well as all applicable local building codes
and regulations. Follow all instructions and
guidelines when venting the boiler units.
Venting should be performed only by a licensed
professional.
88 Installing a Common Vent System
9.1.1 Guidelines for a Common Vent
System
CAUTION
To ensure the correct operation of the
●
common vent system,
a cascade communication cable MUST be
-
installed between all units in the common
vent system by the installer.
backflow vent dampers must be installed
-
in the exhaust duct of each boiler unit.
use direct vent (with separate intake
-
and exhaust vent) or indirect vent
(combustion air drawn from room)
systems.
Common vent installations for use with
●
natural gas and propane are only approved
for up to 4,500 ft.
This section covers the installation of a
●
common vent system for NFC-H boilers only.
To ensure the safe and correct installation of
the common vent system, carefully follow the
instructions and guidelines.
Check to see if all contents are included in the
●
package (refer to the "Included Items" on page
93).
An NFC-H boiler unit and up to 7 NPE water
●
heater units may be connected to one common
vent system. In a cascade system that has more
than 7 NPE water heaters, use 2 common vent
systems, or consult Navien.
Use only approved PVC cements when
●
connecting pipes, joints, or elbows.
Position the boiler units as close as possible to the
●
vent termination.
Install a new vent system with this appliance. If an
●
existing vent system is reused, thoroughly inspect
it for punctures, cracks, or blockages prior to
connecting it to the boiler unit.
Horizontal vent pipe runs must be supported
●
every 4 feet (1.2 m) (minimum). All vertical vent
pipe runs must be supported every 6 feet (1.8 m)
(minimum). Support the vent pipe with hangers
at regular intervals or as required by local codes.
Install a Navien Backflow Damper Kit for each
●
boiler unit. Use only the damper specified in this
manual.