Navien units need annual maintenance to stay inside warranty. Combi boilers have additional hydronic-system maintenance tasks beyond what a pure tankless needs.
Annual checklist — all Navien
- Flush heat exchanger — vinegar or commercial descaler, 60-90 min job. Annual in hard water, biennial in soft water. Non-negotiable
- Clean inlet water filter — small screen at cold-water inlet. Removes sediment before scale forms
- Clean air inlet filter — base of unit. Lint and pet hair restrict combustion air
- Inspect vent termination — clear of leaves, ice, insect nests
- Inspect condensate trap and drain — clean any sediment, verify free flow
- Verify gas pressure — ≥4" WC inlet during fire on NG, ≥10" WC on propane. Test annually with manometer
- Test pressure relief valve — lift handle, verify discharge then reseat
- NaviLink firmware — verify latest version installed
Additional for NPE-A2 (with built-in pump)
- Listen to recirc pump during operation — bearing noise indicates pump approaching end of life
- Inspect recirc check valves — verify proper direction-of-flow
- Verify HotButton wireless button functioning if installed
Additional for combi boilers (NCB, NFC)
- Hydronic system pressure — verify cold pressure 12-15 psi; if dropping over months, investigate the leak
- Expansion tank pre-charge — verify pre-charge pressure matches design (typically 12 psi)
- Air separator — purge air from system at the Spirovent or air vent
- Dirt separator — clean strainer if installed
- Zone valves / circulators — test each zone fires correctly
- 3-way diverter valve — verify smooth operation between DHW and heating modes
- Outdoor reset sensor — verify resistance matches ambient temperature
How often
| Task | Soft water (<7 gpg) | Hard water (>11 gpg) |
|---|---|---|
| Heat exchanger flush | Every 24 months | Every 12 months |
| Inlet water filter | Annually | Twice yearly |
| Air inlet filter | Annually | Annually |
| Vent inspection | Annually | Annually |
| Hydronic pressure / air (combi) | Annually | Annually |
| Outdoor reset calibration (combi) | Every 2-3 years | Every 2-3 years |
DIY vs professional
Filter cleaning and descaling are fully DIY. Gas pressure testing and hydronic system maintenance (combi) need a plumber or heating contractor. Most homeowners DIY the flush and pay an NSS every 2-3 years for a full inspection.
Bottom line
Annual descaling is the single non-negotiable Navien maintenance task. For combi boilers, hydronic-system attention is equally important. Skipping either creates expensive failures and voids warranty claims.