Takagi tankless units need annual maintenance to stay inside warranty and at rated GPM output. Skipping descaling is the most common reason warranty claims are denied.
Annual checklist
- Flush the heat exchanger — annual in hard water, biennial in soft water
- Clean the inlet water filter
- Clean the air inlet filter
- Inspect vent termination
- Inspect condensate trap (condensing models)
- Verify gas pressure (every 2-3 years, by a plumber with manometer)
- Test pressure relief valve if installed inline
- For outdoor units in cold climates: verify freeze-protection circuit is working
T-T commercial cascade — quarterly maintenance
- Cascade controller firmware verification
- Per-unit firing hours review (verify wear leveling)
- Individual unit fault-log review
- Manifold inspection for leaks
- Quarterly descaling in heavy commercial duty
Frequency by water hardness
| Task | Soft (<7 gpg) | Hard (>11 gpg) |
|---|---|---|
| Heat exchanger flush | Every 24 months | Every 12 months |
| Inlet water filter | Annually | Twice yearly |
| Air inlet filter | Annually | Annually |
Warranty impact
Heavy scale at claim time = denied claim. Keep receipts and dated photos.
Bottom line
One Saturday a year keeps a Takagi inside warranty and at rated output for the full 15-year T-H3/T-D2 heat exchanger life.