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Navien · Tankless water heater

E762 Vent pipe not properly inserted

High severity Navien NPE-2Navien NPN

What the control is telling you

The vent installation detector (VID) does not see the vent pipe fully inserted in the exhaust collar. The unit will not run.

Applies to: Navien NPE-A2 (built-in recirculation) and NPE-S2 condensing tankless water heaters: NPE-150S2, NPE-180A2/S2, NPE-210A2/S2, NPE-240A2/S2; also Navien NPN non-condensing tankless water heaters: NPN-160U/180U/199U (universal, indoor or outdoor with vent kit) and NPN-120E/160E/180E/199E (outdoor only)

Likely causes

  • Vent pipe not pushed fully into the collar
  • Wrong pipe size or deformed pipe
  • Pipe pulled out or misaligned

Test and repair steps

  1. Warning: carbon monoxide hazard - do not bypass the VID.
  2. NPE-2 pipe must be 2 in., cut square and deburred, lubricated with water and inserted 2-3/4 in. (70 mm) to the bottom of the collar; tighten the clamp (8 mm socket).
  3. NPN (indoor models) 5 in. concentric pipe inserted 1.3 in. (34 mm) and secured with the self-tapping screw.
  4. Put a straight piece on the collar first. Do not fit a street elbow right at the collar.
  5. Replace damaged or deformed pipe and support the vent every 4 ft horizontally.
  6. After fixing, test the exhaust joints for leaks with a bubble test.

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Source: Navien NPE-A2/S2 User's Information Manual (20049624A), 5.2 Understanding Error Codes, p.18; Navien NPE-A2/S2 Installation Manual, 3.6.2, p.44-45; Navien NPN-U/NPN-E Installation Manual, 3.5.1, p.37-38. Summarized in our own words; check the original manual for your model.

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