How to Clean a Noritz Tankless Water Heater in 7 Steps
On this page 5 sections
To clean a Noritz tankless water heater, first turn off the power and water supply, then connect a vinegar solution to the service ports, circulate it for about 30 minutes to dissolve scale buildup, and finally flush the system with clean water before restoring power and water supply.
Descaling your Noritz tankless water heater is essential for maintaining efficiency and extending its lifespan. Hard water minerals build up over time, reducing heat transfer and increasing energy costs. Follow this detailed guide to properly clean your unit.
Why Descaling Matters
Mineral deposits from hard water accumulate inside the heat exchanger. This buildup:
- Reduces heating efficiency by up to 25%
- Causes overheating and potential damage
- Shortens the heater’s lifespan
Noritz recommends descaling every 1-3 years depending on water hardness. Check your water heater’s expected lifespan to understand maintenance impact.
Tools and Materials Needed
| Item | Purpose |
|---|---|
| Submersible pump (1/6 HP) | Circulates cleaning solution |
| 5-gallon bucket | Holds vinegar solution |
| Food-grade white vinegar (4 gallons) | Dissolves mineral deposits |
| 2 garden hoses (3/4″) | Connects pump to unit |
| Adjustable wrench | Removes drain caps |
Step-by-Step Descaling Process
1. Prepare the Unit
Turn off power and gas supply. Locate isolation valves – red for hot water, blue for cold. Turn both valves to the perpendicular (off) position.
2. Drain Existing Water
Remove drain caps and place bucket underneath. Open hot water drain valve first, then cold. Let all water drain completely.
3. Set Up Circulation System
Connect pump to cold water drain valve with hose. Attach second hose to hot water drain valve, leading back to bucket. This creates a closed loop.
4. Add Cleaning Solution
Pour 4 gallons of vinegar into bucket, submerging pump. For severe buildup, use a commercial tankless water heater descaler instead.
5. Circulate Solution
Open drain valves and run pump for 60-90 minutes. Replace vinegar after 30 minutes for heavy deposits. The unit may display error code 11 – this is normal.
6. Flush the System
Disconnect pump and flush with 20 gallons of clean water. For condensing models, open the drain opener underneath to remove residual solution.
7. Restart the Unit
Replace all caps, turn valves to on position, restore power and gas. Reset the unit to clear error codes. Check our guide on resetting Noritz water heaters if needed.
Water Heater Owner's ToolkitFix the common faults yourself, keep it running for years, and know when a repair is money wasted.No-hot-water flowcharts, gas and electricFlush, anode, relief valve and descaling stepsRepair-or-replace calculator (Excel)Additional Maintenance Tips
Cleaning Internal Components
Every 2-3 years, clean these parts:
- Flame rod (use fine sandpaper)
- Ignition plug
- Fan assembly (brush and compressed air)
- Burner chamber
Water Filter Maintenance
Clean the inlet water filter monthly:
- Turn off water supply
- Remove filter with adjustable wrench
- Rinse under running water
- Reinstall securely
Preventing Future Buildup
Consider these options to reduce descaling frequency:
- Install a water softener
- Use a Noritz anti-scale treatment device
- Add a whole-house filter
- For outdoor units, read about preventing freeze damage
Proper maintenance keeps your Noritz tankless water heater running efficiently for its full 20-year lifespan. Always consult your owner’s manual for model-specific instructions.
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