Navien NHB Series User Manual

21Installing the System Piping
Air Vent
The Navien NFB boiler comes with an air vent and an adapter
bushing that must be connected to the air vent connection. The
vent efficiently removes the air from the space heating system.
The following figure illustrates an example of a typical air vent
installation.
Note
Install the pressure relief valve onto the adapter before
the air vent. The pressure relief valve may interfere with
the air vent if not installed first.
Return
Air Vent
Bushing
Air Vent
Pressure
Relief Valve
Supply
Note
After installing the air vent bushing to the air vent
connection and inserting the PRV-air vent adapter into
the air bushing, install the provided clip between the
air vent bushing and the PRV-air vent adapter to secure
the adapter to the fitting.
Clip
PRV-Air Vent
Adapter
2
1
3
Air Vent
Bushing
PRV-Air Vent
Connection
Note
To apply the supply top piping, install a tee to the air
vent connection and connect a double nipple to the
tee and the air vent bushing.
Supply
Return
Tee
Pressure
Relief Valve
Air Vent Bushing
Double Nipple
Auto
Air
Vent
<Supply Top / Return Top>
Pressure
Relief Valve
Auto Air Vent
Supply
Return
<Supply Bottom / Return Top>
Note
Use the supplied caps with gaskets to close off any
unused supply or return connections.

Navien NHB Series Specifications

General

Type	Condensing Boiler
Efficiency	Up to 95% AFUE
Fuel Type	Natural Gas or Propane
Vent Type	Direct Vent
Vent Diameter	2" or 3"
Heat Exchanger Material	Stainless Steel
Water Connections	3/4" NPT
Dimensions	Varies by model
Weight	Varies by model
Warranty	5-Year Parts