Noritz tankless units need annual maintenance to stay inside warranty and at rated GPM output. The ecoTOUGH 316L stainless heat exchanger is more scale-tolerant than most competitors, but not maintenance-free. Skipping descaling is the most common reason warranty claims are denied.
Annual checklist — all Noritz
- Flush the heat exchanger — vinegar or commercial descaler, 60-90 min job. Annual in hard water (>11 gpg), every 2 years in soft water
- Clean the inlet water filter — small screen at the cold-water inlet. Removes sediment before it scales the exchanger
- Clean the air inlet filter — at the base of the unit. Lint and pet hair restrict combustion air
- Inspect the vent termination — clear of leaves, ice, insect nests
- Inspect the condensate trap on condensing models — clean if any sediment buildup
- Verify gas pressure — should be ≥4" WC inlet during fire on natural gas, ≥10" WC on propane. Test annually
- Test the pressure relief valve if installed inline
- For EZTR: listen to recirc pump during operation — bearing noise indicates end of life approaching
Additional for NRCB combi boilers
- Hydronic system pressure — verify cold pressure 12-15 psi; investigate any drop
- Expansion tank pre-charge — verify matches design (typically 12 psi)
- Air separator — purge air from system at the Spirovent or air vent
- Dirt separator — clean strainer if installed
- 3-way diverter valve — verify smooth operation between DHW and heating modes
- Outdoor reset sensor — verify resistance matches ambient temperature
Additional for NCC commercial cascade
- Cascade controller firmware — verify latest version
- Rotation log review — verify all units in cascade have similar firing hours (wear leveling working)
- Individual unit error logs — review each unit's controller for any captured faults
- Manifold inspection — check for leaks at gas, water, condensate manifolds
- Quick Connect cord inspection — verify all unit connections are secure and undamaged
- Isolation valves — test individual unit isolation while cascade stays online
How often does each task happen?
| 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 |
| Gas pressure check | Every 2-3 years | Every 2-3 years |
| Cascade controller review (commercial) | Annually | Annually |
Warranty impact
Noritz's warranty requires "performed annual maintenance in accordance with installation manual." Heavy scale at warranty claim time = denied claim. Keep flush receipts or take photos with date.
Commercial duty cycle considerations
NCC commercial units in restaurant/hotel duty often run 12-16 hours per day at meaningful load. The cascade rotation distributes wear, but individual unit firing hours add up. For high-duty-cycle commercial: more frequent descaling (every 6-9 months in hard water), more frequent filter inspection (quarterly), and dedicated annual professional service contracts are common.
Bottom line
One Saturday morning per year for residential. For commercial NCC cascade: a dedicated service contract with quarterly visits and cascade controller monitoring is the right pattern. The ecoTOUGH heat exchanger longevity advantage only materializes if you actually maintain the unit.