Navien NFC-250/175H, Руководство по установке, Страница: 27 / 151

27 Installing the System Piping
The DHW pressure relief valve is not supplied,
but is required.
The following examples are pressure relief valves
approved for use
with the boiler:
●
Wilkins P-1000A (Zurn Industries)
●
Conbraco 17-402-04
●
Watts Industries 3L (M7)
●
Cash Acme FWL-2,
3
/
4
in
Pressure
Relief
Valve
CAUTION
Install the pressure relief valve as close to the
boiler as possible. No other valve should be
installed between the pressure relief valve and
boiler.
When installing pressure relief valve, follow these
guidelines:
●
Ensure that the valve’s discharge capacity is equal
to or greater than the maximum pressure rating
of the boilers DHW system.
●
Ensure that the maximum BTU/H rating on the
pressure relief valve is equal to or greater than the
maximum input BTU/H rating of the boiler.
●
Direct the discharge piping of the pressure
relief valve so that hot water does not splash on
operator, or any nearby equipment.
●
Attach the discharge line to the pressure relief
valve and run the end of the line to within 6-12 in
(150 300 mm) of the floor.
●
Ensure that the discharge line allows for free and
complete drainage without restriction. Do not
install a reducing coupling or other restrictions on
the discharge line.
●
If the relief valve discharges periodically, this may
be due to thermal expansion in a closed water
supply system. Contact the water supplier or
local plumbing inspector on how to correct the
situation. Do not plug the relief valve.
Navien is not responsible for performance issues of
the domestic system by scaling or accumulation of
dirt; suitable steps shall be taken by the installer and
user to avoid water quality related issues.
Freeze Protection
Navien recommends heat tracing and insulating the
DHW water pipes. Pipe enclosures may be packed
with insulation for added freeze protection. Freeze
damage is not covered by the warranty.
3.2.2 Essential Elements in a DHW
System
DHW Heat Exchanger
The DHW heat exchanger installed inside the
Navien NFC-H boiler has been tested and certified in
accordance with the latest IAPMO standard PS 92.
Drain and Isolation Valves
Install drain and isolation valves on the inlet and
outlet of the DHW heat exchanger, so it can be
flushed free of possible build-up caused by dirt or
hard water.
Pressure Relief Valve for DHW
To complete the installation of the DHW system,
you must install an approved
3
/
4
in, maximum 150
psi pressure relief valve on the hot water outlet. The
Navien NFC-H boiler has a built-in high temperature
shut off switch, so install a “pressure only“ relief
valve.
WARNING
Installing the pressure relief valve improperly
may result in property damage, personal injury,
or death. Follow all instructions and guidelines
when installing the pressure relief valve. The
valve should be installed only by a licensed
professional.