Navien NFB-175H, Installation Manual, Page: 29 / 135

29 Installing the System Piping
1. Fill the system only after ensuring that the water
chemistry meets the requirements.
Contaminant Maximum Allowable Level
Total Hardness
Up to 200 mg/l
(12 grains/gallon)
Aluminum 0.05 to 0.2 mg/l
Chloride Up to 250 mg/l
Copper Up to 1.0 mg/l
Iron Up to 0.3 mg/l
Manganese Up to 0.05 mg/l
pH 6.5 to 8.5
Sulfate Up to 205 mg/l
Total Dissolved
Solids (TDS)
Up to 500 mg/l
Zinc Up to 5 mg/l
Chlorine Up to 4 mg/l
Note
Proper maintenance of the boiler is
required when water quality does
not meet standards. Damage caused
by poor water quality is not covered
under warranty. The table above shows
the maximum contaminant levels
allowed. If you suspect that your water is
contaminated in any way, discontinue the
use of the boiler and contact an authorized
technician or licensed professional.
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.
3.3.1 Make-up Water Connection
An external make-up water connection is required.
The illustration below shows an example of an
external water supply connected to the system
piping.
Pressure Relief Valve
Air Separator
Pump
Expansion Tank
To
System
Make-up
Water
From
System
3.4 Testing the Water System
WARNING
Ensure that the boiler is full of water before
firing the burner. Operating the unit without
completely filling it will damage the boiler. Such
damage is not covered by the warranty, and
may result in property damage, severe personal
injury, or death.
Perform a leak test after installing the boiler’s water
system to make sure that the system has been
installed properly. Follow the instructions below to
perform a fill test on the water system.