Navien NR-180 Installation Manual page 26

Gas Water Heater Installation
█ 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.
 Exhaust pipe and intake air pipe must be supported every 5 feet.
Navien and Direct Vent:
 All Navien Water Heaters are prepared at the factory to be direct vent (sealed
combustion) units which draw all of their required combustion air directly from
outside the building.
 All Navien Water Heaters 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 vent
and air intake vent must be sealed airtight from unit collar to terminator.
 The intake air pipe materials can be made of ABS, PVC, CPVC, 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. This situation may freeze
the water heater's heat exchanger. According to the building codes in most
jurisdictions, negative pressures in homes are 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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