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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.
The pressure relief valve must be installed at
●
the boiler outlet and in the vertical position,
as shown in this section, with the drain pipe
outlet exiting the side of the pressure relief
valve horizontally and elbowing down.
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 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.
Air Vent
External LWCO
Method 1.
Refer to the following illustration for a pressure relief
valve installation in the space heating system. Watts
174A pressure relief valve (
provided with the boiler.
Method 2.
Depending on the installation
Note
●
conditions, pressure relief valves (not
included and for separate purchase) of
up to 80 psi can be used.
Refer to "11.13.3 Setting the Operation
Parameters - 17. High Sys Pressure" on
page 111 to adjust the upper limit
pressure lockout setting when using a
higher rated valve.
All separately purchased pressure
●
relief valves must be ASME certified.
Pressure
Relief Valve
/
in, HV, Max 30 psi) is
3
4
Pressure Relief
Valve
Installing the System Piping
19
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