Navien CH-180 Installation Manual page 35

Venting:
Do not store hazardous or flammable substances near the vent terminator.
If this product will be installed in an area where snow is known to accumulate,
protect the vent termination from blockage.
Vent terminator must be a minimum of 12" above ground.
Support the vent pipe with hangers at regular intervals or as required by local code;
the weight of the vent pipe must not rest on the Water Heater / Heating Boiler.
Exhaust pipe and intake air pipe must be supported every 5 feet.
The installation of the venting system shall specify that the horizontal portions of the
venting system shall be supported to prevent sagging;
- Have horizontal runs sloping upwards not less than 1/2 inch per foot from the water
heater/boiler to the vent terminal;
- Be installed so as to prevent accumulation of condensate; and
- Where necessary, have means provided for drainage of condensate.
All Navien Combination Water Heater / Heating Boilers are prepared at the factory to be
direct vent (sealed combustion) units which draw all of their required combustible air
directly from outside the building.
All Navien Combination Water Heater / Heating Boilers use 3" diameter exhaust and 3"
diameter intake air duct. To ensure the draw and exhaust of air directly to and from the
outside, the exhaust pipe and intake air duct must be sealed airtight from unit collar to
terminator.
The air intake vent materials can be made of ABS, PVC, galvanized steel, corrugated
aluminum or any other such materials. If you are using a corrugated material, ensure
there is no inadvertent crimping of, or damage to, the intake air pipe.
Navien and Non-Direct Vent:
Navien recommends direct vent installations whenever possible to avoid back
drafting cold air through the unit, if you cannot use direct vent, it is essential to have
an ample supply of make-up air.
If at any time, the building experiences a negative pressure situation when using a non-
Direct Vent unit, there is a possibility of back drafting cold, winter air from outside
through the heat exchanger of the Water Heater / Heating Boiler. This situation may
freeze the Water Heater / Heating Boiler's heat exchanger. According to the building
codes in most jurisdictions, a negative pressure in homes is not allowed. In a home with
a well-balanced air supply, freezing of the heat exchanger will not occur.
Since the cause of the back drafting is insufficient make-up air within the home or
building. This will not be deemed a manufacturing problem and any freezing
damage which occurs from back drafting will not be covered under warranty. To
avoid any such issues in colder climates, Navien requires the use of direct vent.
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