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NOTICE
For systems requiring freeze protection, use only
inhibited propylene glycol, specially formulated
for hydronic heating systems; use of other types
of antifreeze may be harmful to the system and
will void the warranty.
System Pressure
The Navien NHB-H boiler is intended solely for
●
use in pressurized closed loop heating systems
operating with 12-30 psi water pressure at the
boiler outlet. To obtain the minimum system
design pressure, follow the piping diagrams
illustrated in this section.
The Navien NHB-H boiler's space heating system
●
is not approved for operation in an "open system",
thus it cannot be used for direct potable water
heating or to process heating of any kind.
Oxygen Elimination
This boiler may only be installed in a pressurized
closed-loop heating system, free of air (oxygen)
and other impurities. All of the air should be
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
Note
at the end of this section detailing
the installation location of the air
removal device, in case an additional air
removal device is required for a specific
application.
NOTICE
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.
Do not solder piping directly onto the water
●
connections, as the heat may cause damage
to internal components. Use threaded water
connections only.
Failure to follow these instructions may result in
●
poor performance, unnecessary wear of system
components and premature failure.
3.1.2 Essential Elements in a Space
Heating System
Air Vent
The Navien NHB-H 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.
Return
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 17
and "Pressure Relief Valve" on page 18.
Before installing the vent line and any
Note
vent fittings, you must be familiar with
the LWCO and pressure relief valve
installation guidelines.
Low Water Cut Off (LWCO) Device
Internal LWCO
The Navien NHB-H boiler is equipped with a factory-
installed, pressure-sensing type low water cutoff
(LWCO) device. The minimum operation pressure for
this device is 6 psi by default.
When the built-in water pressure sensor
Note
detects insufficient water level in the
boiler, error code E302 is displayed on the
front panel requiring a manual boiler reset.
Refer to local codes to determine if a LWCO device is
required for your system and ensure that the built-in
device meets the requirements.
Air Vent
Air Vent
Bushing
Installing the System Piping
17
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