Your Navien water heater may be making noise due to sediment buildup, water flow issues, or expansion and contraction of components during heating; regular maintenance can help prevent these sounds.
Navien tankless water heaters are known for efficiency, but unusual noises can signal problems. From revving fans to vibrating pipes, we’ll explain every sound and how to fix it.
Common Navien Water Heater Noises and Causes
1. Revving or Whining Noise After Shutoff
Many Navien owners report loud revving sounds after turning off hot water. This typically lasts 30 seconds to 5 minutes. The culprit is usually:
- Internal recirculation pump (Dip Switch 1 ON)
- Gas purge cycle
- Inducer fan bearing wear
As one user reported: “It revs so loud you can hear it two floors up for about 30 seconds after taps close.” This often occurs with internal recirculation mode. Switching to external recirculation or turning off recirculation (all DIP switches OFF) typically solves it.
2. Water Hammer Effect
Banging in pipes during recirculation indicates water hammer. This happens when:
- Fast-closing valves stop water flow abruptly
- Pressure/temperature variations exist in recirculation lines
- Expansion tank is missing (required when using storage tanks)
Install an expansion tank and consider adding a recirculation pump with slower start/stop features.
3. Vibrating or Whistling Sounds
New vibrations or whistling often stem from:
| Sound | Likely Cause | Solution |
|---|---|---|
| Vibration on startup | Loose cabinet panels | Tighten all 4 enclosure screws |
| Whistling at vents | Unsealed intake/exhaust pipes | Check pipe seals and gaskets |
| Rumbling | Dirty air intake screen | Clean every 6-12 months |
Advanced Troubleshooting Steps
Checking Recirculation Settings
Navien’s dip switch settings control recirculation behavior:
- Switch 1 ON: Internal recirculation (common noise source)
- All OFF: No recirculation (quietest option)
- External mode: Requires dedicated recirculation pump
One user resolved noise by: “Turning off dip switch 1 (internal recirculation mode). The noise went away completely.”
Testing for Overheating
If your unit shows higher temps than set (e.g., 131°F when set to 125°F):
- Check flow rate (minimum 0.6 GPM for Navien)
- Inspect heat exchanger for scale buildup
- Verify thermostat calibration
Inspecting Mechanical Components
For persistent noises:
- Inducer fan: Check for bearing wear or debris
- Water strainer: Clean annually (prevents flow issues)
- Gas valve: Ensure proper purge cycle timing
When to Call a Professional
Contact Navien support (1-800-519-8794) or a technician if you experience:
- Persistent revving after recirculation is disabled
- Water temperature fluctuations exceeding 5°F
- Error codes with unusual sounds
- Suspected gas valve or heat exchanger issues
For complex installations with storage tanks, ensure proper expansion tank sizing to prevent pressure-related noises.
Preventive Maintenance Tips
Reduce noise problems with regular care:
- Flush annually with descaling solution
- Clean air intake screen every 6 months
- Check pipe insulation to prevent thermal expansion noises
- Verify all mounting brackets are secure
Proper maintenance can prevent 80% of noise issues in Navien units. For recirculation systems, consider upgrading to quieter external pumps if internal mode causes disturbances.
