25Installing the System Piping
Contaminant Maximum Allowable Level
Total Hardness 200 mg/l (12 grains/gallon)
Aluminum 0.05 to 0.2 mg/l
Chloride 250 mg/l
Copper 1.0 mg/l
Iron 0.3 mg/l
Manganese 0.05 mg/l
pH 6.5-8.5
Sulfate 205 mg/l
2. Close the manual and automatic air vents and the boiler drain
valve.
3. Fill the boiler to the correct system pressure. The correct
pressure will vary with each application. The typical cold water
fill pressure for a residential system is 12 psi. The pressure
will rise when the boiler is turned on and the system water
temperature increases. The operating pressure must never
exceed the relief valve pressure setting.
4. At initial fill and during boiler start-up and testing, check
the system thoroughly for leaks. Repair any leaks before
proceeding further.
WARNING
Eliminate all system leaks. The continual introduction of fresh
makeup water will reduce boiler life. Minerals can build up in
the heat exchanger, reducing heat transfer, overheating the
heat exchanger and causing heat exchanger failure.
The system may have residual substances that could affect water
chemistry. After the system has been filled and leak tested,
verify that water pH and chlorine concentrations are within the
acceptable range by performing sample testing.
CAUTION
Before operating the boiler for the first time, ensure that the
boiler system is filled with water. Purge the air inside the
system to avoid damage to the boiler.
3.5 Examples of System Applications
Refer to the following examples to properly implement a system
for space heating, DHW supply, or both. These examples are
provided to suggest basic guidelines when you install the boiler
system. However, the actual installation may vary depending on
the circumstances, local building codes, or state regulations. Check
the local building codes and state regulations thoroughly before
installation, and comply with them fully.
3.5.1 Considerations for System Applications
Read and follow the guidelines listed below when installing system
piping for the Navien NHB boiler:
System application drawings are intended to explain the system
piping concept only.
When installing a mixing valve on the DHW piping, ensure that
the cold water pressure does not exceed the hot water pressure.
For the upstream side of all pumps, use straight pipes with a
minimum inside diameter of
1
/
2
in (12 mm).
Provide a system expansion tank following the guidelines on
page 18.
Installations must comply with all local codes. In Massachusetts,
a vacuum relief valve must be installed in the cold water line per
248 CMR.
Air Removal
The boiler and system plumbing layout must be configured to
promote the removal of air from the water. Air vents and bleeders
must be strategically placed throughout the system to aid in
purging the air from the system during commissioning of the
boiler. The system must also employ the use of a strategically
located air removal device, such as an air scoop or an air eliminator
designed to remove the air from the water as it flows through the
system.
Follow the installation instructions included with the air removal
device when placing it in the system; air removal devices generally
work better when placed higher in the system. Always locate air
removal devices in areas of the system that have a guaranteed
positive pressure, e.g., in close proximity to the water fill and
expansion tank.
Note
Connecting an air vent on top of the boiler is
recommended.
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