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Navien · Combi boiler

E762 Vent pipe not fully inserted (VID)

Critical severity Navien NCB-HNavien NFC-H

What the control is telling you

The Vent Installation Detector switch in the exhaust collar does not detect a fully inserted vent pipe; the boiler will not run. NFC-H manual lists the reset type as: Auto reset.

Applies to: Navien fire-tube combi boilers, NFC-H series (NFC-250/200H, NFC-250/175H) and NCB-H combi boilers (NCB-250/150H, NCB-240/130H, NCB-240/110H, NCB-190/080H, NCB-190/060H)

Likely causes

  • Vent pipe not pushed fully 2-3/4 in (70 mm) into the collar
  • Wrong pipe size, deformed pipe, misaligned or moving pipe
  • Street elbow used at the collar

Test and repair steps

  1. Warning: carbon monoxide hazard - do not run the boiler with a loose vent connection.
  2. Mark the pipe 2-3/4 in (70 mm) from the end, cut square (90°) and deburr, lubricate with water (not grease) and push in with a twist until the mark disappears.
  3. Use the correct 2 in pipe at the collar; never start the run with a street elbow - use a straight length.
  4. Tighten the collar clamp (8 mm socket) and support the pipe so it cannot move vertically.
  5. Bubble-test the exhaust joints with the boiler running.
  6. Note the VID does not detect leaks or separation further along the vent; inspect the whole run.

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Source: Navien NCB-H Installation & Operation Manual, 11.7 Understanding Error Codes, p.129-130; Navien NFC-H Installation Manual, 11.7 Understanding Error Codes, p.127-128. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.