Navien NPN Installation & Operation Manual page 42

Vertical Termination
Use a condensate collector in all installations.
3.5.5 Draining Condensate (Indoor
Models Only)
WARNING
If a condensate trap hose is installed, the water
inside the hose should be higher than 5.1 in
(130 mm), and water should be inside the hose
before operating the water heater. Do not
remove the condensate collector cap unless
a condensate trap is attached. If a condensate
trap is not installed properly as explained above,
it could result in injury or death.
The water heater will create condensation when it
operates.
Condensate will eventually damage the heat
exchanger if it is not drained properly. Follow all
local codes and regulations when disposing the
condensate from the water heater.
5.1 in
(130 mm)
Installing the Water Heater 41