Navien NHB-55 Quick Installation Manual page 2

Gas Piping Connections
The gas meter capacity must be
greater than the total gas capacity
of connected appliances.
Gas
Regulator
Gas supply
Gas inlet adapter
Bottom View
Water Piping Connections
Space Heating System
A pressure relief valve must be installed when installing
pipings for a heating system.
Install the included 3/4 in, maximum 30 psi pressure
relief valve on the space heating supply.
An ASME approved HV pressure relief valve for space
heating system is supplied with the boiler.
You may install the pressure relief valve on the space
heating supply of the Navien Manifold System, or on
the top connection along with the air vent (and an
external LWCO, if required).
Do not solder piping directly onto
Caution
the water connections, as the heat
may cause damage to internal
components. Use threaded water
connections only.
System Fill Connection
The Navien NHB boilers have a top
connection for an air vent. An air vent must
be installed to purge air from the boiler
system.
When installing the air vent, install the air
vent bushing between the air vent and the
top connection.
Condensate Drain Connection
A condensate drain pipe must be connected to the 1/2 in condensate outlet fitting at
the bottom of the unit and water must be poured into the exhaust connection to fill
the condensate trap.
NPT 1/2 in
Gas Supply Line
The boiler is recommended to be the first
appliance to be connected to the gas
supply line.
Drip rig
Air Bent
External LWCO
Air Vent Cap
Before filling the boiler, remove the air vent
cap to allow the system to fill properly.
Air Vent
Replace the cap when the system is full.
Air Vent Bushing
Ensure that the Air Vent Cap is removed
Warning
before filling the system.
System will not be properly filled without
the air vent cap removed. Air in the
system may cause malfunctions and
system overheating.
Syphon
Water
Condensate Outlet
Floor drain
Example:
Gas meter Boiler
≥
425 CFH 195 CFH
* 1 CFH=1,020 Btuh
• 1/2 in rigid pipe can be used; refer to the sizing tables in the Installation
Manual for limitations. Avoid using 1/2" corrugated connectors or tubing as
noise may occur.
Water Piping Connections
Pressure
Relief Valve
Rubber
Grommet
Pressure
Relief Valve
From
System
The end of the 1/2 in (NPT) plastic piping should drain into a laundry tub or into a
floor drain.
Do not submerge the end of the
Note
pipe in water.
2
+ Furnace + Domestic gas stove
58.8 CFH 63.7CFH
Space Heating
Condensate
Supply
Outlet
Space Heating Gas Connection
Return
Pressure Relief Valve
Air Separator
Circulator
To system
Make-up
Water
Expansion Tank
Direct to the
To the laundry
external drain
tub
To the laundry tub
via a condensate
pump
To the drain
via a neutralizer
External drain