Navien NHB-055 Installation & Operation Manual page 14

Adequate Installation Clearances
CAUTION
Do not install the boiler on carpeting.
Install the boiler in an area that allows for service and maintenance
access to utility connections, piping, filters, and traps. Based on
the installation location, ensure that the following clearances are
maintained:
Back
Side
Clearance from:
Top
Back
Front
Sides
Bottom
14 Installing the Boiler
Top
Side
Front
Bottom
Indoor Installation
9 in (229 mm) minimum
0.5 in (13 mm) minimum
4 in (100 mm) minimum
3 in (76 mm) minimum
12 in (300 mm) minimum
CAUTION
It is necessary to leave clearance for service access.
Clean, Debris and Chemical-free Combustion Air
Do not install the boiler in areas where dust and debris may
accumulate or where hair sprays, spray detergents, chlorine, or
similar chemicals are used.
Do not install the boiler in areas where gasoline or other
flammables are used or stored.
Ensure that combustible materials are stored away from the
boiler and that hanging laundry or similar items do not obstruct
access to the boiler or its venting.