Navien NP Condensing Tankless Gas Water Heater - Service Manual

5.21. 37Error
Error occurrence conditions and check items.
Error
37E
Internal water
leak
Check items
Description
If the water leak sensor signal is detected while the water heater is ON, the system
displays 37E (cleared manually). The water heater enters the Lock-Out mode
(gas valve and ignition transformer closed), and closes the flow control valve to
prevent further water leak.
For the cascade system
1. If the water leak signal is sensed in one out of two units, the system blocks direct
water of the all units to prevent water leak.
2. If three or more units are installed, the system blocks cold water for the
concerned unit only.
3. To block the cold water, the system completely closes the water adjustment valve.
1. Visually check heat exchanger and piping for leaks.
2. Check if the PCB water level sensor works normally.
3. Check if the PCB works normally.
Is there any water leakage
inside water heater?
No
Is there any water leakage
detector normally
operating?
No
Replace water leakage detector
Yes
Yes
Replace leaking part
Check connector
110
©Navien America Inc. 2010
NR/NP series service Manual
Version 2.0