Navien NFC-175 Installation & Operation Manual page 20

Oxygen Elimination
This boiler may only be installed in a pressurized closed-loop
heating system, free of air (oxygen) and other impurities. To avoid
the presence of oxygen, ensure all of the air is removed from
the system during commissioning via strategically placed and
adequately sized air removal appliances, located throughout the
heating system.
See the examples of system application at the end of
Note
this section detailing the installation location of the air
removal appliances, in case an additional air removal
appliances is required for a specific application.
WARNING
Immediately repair any leaks in the system piping to avoid
●
adding make-up water. Make-up water adds oxygen and
minerals to the system that may lead to heat exchanger
failure.
Failure to follow these instructions may result in poor
●
performance, unnecessary wear of system components and
premature failure.
CAUTION
Do not solder piping directly onto the water connections,
as the heat may cause damage to internal components. Use
threaded water connections only.
20 Installing the System Piping
3.1.2 Essential Elements in a Space Heating System
Air Vent
The Navien NFC boiler comes with an air vent and an adapter
bushing that must be connected to the air vent connection. The
vent efficiently removes the air from the boiler. The following figure
illustrates an example of a typical air vent installation.
Pressure
Relief Valve
Air Vent Cap
After inserting the PRV-air vent adapter into the
Note
connection on top of the unit, install the provided clip
to secure the adapter to the fitting.
1
PRV-Air
Vent
Adapter
2
Clip