Navien NFB-175H, Руководство по установке, Страница: 21 / 135

21 Installing the System Piping
Refer to the following illustration for a pressure relief
valve installation in the space heating system. Watts
174A pressure relief valve (
3
/
4
in, HV, Max 30 psi) is
provided with the boiler.
Pressure Relief
Valve
Method 2.
Note
Depending on the installation
conditions, pressure relief valves (not
included and for separate purchase) of
up to 80 psi can be used.
Refer to “11.6.3 Setting the Operation
Parameters - 17. High Sys Pressure” on
page 107 to adjust the upper limit
pressure lockout setting when using a
higher rated valve.
CAUTION
All separately purchased pressure relief valves
must be ASME certified.
3.1.3 Space Heating System Piping
When connecting the space heating system, follow
these guidelines:
●
Carefully tighten all connections to avoid damage
to fittings.
●
After installing the boiler, check the space heating
system’s operation and inspect for leaks.
The optional Navien manifold system enables easy
separation of the boiler (primary loop) from the
system (secondary loop(s)). Refer to the illustration
below for an example of the piping connections for
a Navien manifold system (primary zone).
When installing the 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 boiler’s space heating 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 the
operator or equipment.
●
Attach the discharge line to the pressure relief
valve and install the end of the line within 6-12 in
(150-300 mm) above the floor.
●
Ensure that the discharge line provides complete
and unobstructed drainage. Do not install a
reducing coupling or other restrictions on the
discharge line.
If the relief valve discharges periodically, this may be
caused by thermal expansion when the expansion
tank is full or undersized. Do not plug the relief valve.
There are two pressure relief valve installation
methods. In Method 1, the pressure relief valve is
installed on top of the boiler and in Method 2 it is
installed in a manifold system.
If the installed system does not have a Navien
manifold system, install a pressure relief valve with
the air vent. The illustration below shows an example
of a pressure relief valve installed with the air vent.
Method 1.
External
LWCO
Air Vent
Pressure
Relief Valve