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Navien · Combi boiler

E110 Exhaust blockage / abnormal air pressure (APS)

High severity Navien NCB-HNavien NFC-H

What the control is telling you

The air pressure sensor sees a blocked exhaust or intake. The user manual notes a clogged air intake filter will stop the boiler with this code. NFC-H manual lists the reset type as: Manual 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

  • Blocked exhaust pipe or termination (snow, ice, debris, nests)
  • Clogged air intake filter
  • Vent too long or too many elbows
  • Condensate backing up in the vent/trap

Test and repair steps

  1. Make sure the exhaust pipe and termination are free of obstructions (the manual's listed remedy).
  2. Clean the air intake filter; the user manual recommends cleaning it every 3-4 months.
  3. Check vent length 2 in max 65 ft with up to 6 elbows; 3 in max 150 ft with up to 8 elbows (90° elbow = 8 ft on 2 in, 5 ft on 3 in).
  4. Check the condensate trap is filled and drains freely.
  5. Compare Status Information 20. Fan Target APS with 21. Fan Current APS.
  6. Reset from the front panel by pressing the Back button, then confirm the code clears.
  7. Code keeps returning? Phone Navien Technical Support, 1-800-519-8794.

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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.

Homeowner looking at this code? See what it means for you and when to call a technician.

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.