Navien NHB Series User Manual

78 Installing a Common Vent System
9.3 Starting the Common Vent System
9.3.1 Backflow Damper Assembly
Follow the instructions below to assemble the backflow damper
on the NFB boiler unit:
1. Remove the screws from the exhaust vent adapter.
2. Detach the exhaust vent adapter.
3. Connect the backflow damper to the exhaust duct of the boiler
unit.
4. Tighten the four mounting screws to secure the backflow
damper in place. The screws (x 4) are supplied with the
backflow damper.

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