Navien NCB-190/060H, Руководство по установке и эксплуатации, Страница: 20 / 145

20 Installing the System Piping
3.1.2 Essential Elements in a Space
Heating System
Low Water Cut Off (LWCO) Appliance
Internal LWCO
The Navien NCB-H boiler is equipped with a factory-
installed, pressure-sensing type low water cutoff
(LWCO) device. The minimum operation pressure for
this device is 7.3 psig.
Note
●
The boiler performs water
replenishment automatically when
the built-in water pressure sensor
detects insufficient water level in the
boiler system.
●
If the water replenishment is not
completed after
5 minutes, error code E351 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. Install a backflow
preventer in the make-up water line to the unit if
required by local codes.
External LWCO
Install a separate LWCO device if required by local
codes. The following figure illustrates an example of
typical LWCO installation.
External LWCO
6" (152 mm) min.
Figure 1. External LWCO
(without Navien Manifold System)
System Pressure
●
The Navien NCB-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 NCB-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. 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.
Note
See the examples of system application
at the end of 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.