Navien NFB Series Installation & Operation Manual page 18

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 devices, 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 device, in case an additional air removal device
is required for a specific application.
WARNING
Immediately repair any leaks in the system plumbing 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 the heat may cause damage to internal components.Use
threaded water connections only.
18 Installing the System Piping
3.1.2 Essential Elements in a Space Heating System
Air Vent
The Navien NFB 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 space heating system.
The following figure illustrates an example of a typical air vent
installation.
Air Vent
Air Vent
Bushing
Supply
Also, an external LWCO and a pressure relief valve can be installed
at the air vent connection. Refer to "Low Water Cut Off (LWCO)
Device" on page 19 and "Pressure Relief Valve" on page 20.
Before installing the vent line and any vent fittings,
Note
you must be familiar with the LWCO and pressure relief
valve installation guidelines.
Circulation
Pump
Return