Installing The System Piping; Installing A Space Heating System - Navien NFC-175 Installation & Operation Manual

3. Installing the System Piping

Prior to connecting piping to the boiler, flush the entire system
to ensure it is free of sediment, flux, solder, scale, debris or other
impurities that may be harmful to the system and boiler. During
the assembly of the heating system, it is important to keep the
inside of the piping free of any debris including construction dust,
copper burr, sand and dirt.
For retrofits, all system piping including radiators, must be cleaned
of all build-up including sludge and scale. All systems, old and new,
must be cleaned to remove flux, grease and carbon residue. Navien
recommends cleaning the boiler system with cleaning products
specially formulated for boiler systems. For retrofit applications
with heavy limescale and sludge deposits, a heavier duty cleaner
may be required. For information on performing the cleaning,
follow the instructions included with the boiler system cleaner
products.
WARNING
Failure to rid the heating system of the contaminants listed
above will void your warranty and may result in premature
heat exchanger failure and property damage.

3.1 Installing a Space Heating System

The fire-tube type heat exchanger of the Navien NFC boiler is
designed to attain the highest level of heat transfer in a compact
design. To accomplish this, the heated gas flows through a series
of small-diameter tubes, maximizing the heat transfer area. To
maintain the efficient and reliable operation of the heat exchanger,
and to avoid heat exchanger failure, it is critical to ensure the rules
and guidelines in this section are followed.
CAUTION
Failure to follow the instructions provided in this section will
void the warranty and may result in property damage, fire,
serious injury or death.
3.1.1 Guidelines for a Space Heating Installation
Read and follow the guidelines listed below to ensure safe and
proper installation of a boiler heating system.
Freeze Protection for a Space Heating System
Freeze protection products may be used for the space heating
●
system. Freeze protection for new or existing systems requires
specially formulated glycol, which contains inhibitors to prevent
the glycol from attacking the metallic system components.
Before using freeze protection products, ensure that system
●
fluid contains proper glycol concentration and the inhibitor level
is appropriate. Navien recommends against exceeding a 50%
concentration of glycol.
When using the freeze protection products, the system must
●
be tested at least once a year, and as recommended by the
manufacturer of the glycol solution.
When using the freeze protection products, allowance should be
●
made for expansion of the glycol solution.
Freeze damage is not covered by the warranty.
●
The use of glycol results in a greater head loss due to its higher
●
viscosity compared to water.
WARNING
For systems requiring freeze protection, use only inhibited
propylene glycol, specially formulated for hydronic heating
systems; use of other types of antifreeze may be harmful to the
system and will void the warranty.
System Pressure
The Navien NFC boiler is intended solely for use in pressurized
●
closed loop heating systems operating with 12-80 psi water
pressure at the boiler outlet. To obtain the minimum system
design pressure, follow the piping diagrams illustrated in this
section.
The Navien NFC boiler's space heating system is not approved
●
for operation in an "open system", thus it cannot be used for
direct potable water heating or to process heating of any kind.
Installing the System Piping 19