Rinnai · Water heater
Code 65 Low water flow
What this code means
The unit isn't detecting the minimum flow rate needed to fire up.
Most likely causes
- Clogged inlet water filter/screen
- Partially closed isolation valve
- Low household water pressure
What to try first
Check the small inlet filter screen (often behind a removable cap on the cold inlet) for sediment buildup.
Good news: this one is often fixable without a service call. If it persists after the steps above, have it looked at.
Find the part on Amazon →FAQ
What does Rinnai error code Code 65 mean?
Low water flow. The unit isn't detecting the minimum flow rate needed to fire up.
Can I fix Rinnai code Code 65 myself?
Often, yes. Check the small inlet filter screen (often behind a removable cap on the cold inlet) for sediment buildup.
What causes Rinnai code Code 65?
The most common causes are: clogged inlet water filter/screen; partially closed isolation valve; low household water pressure.
Other Rinnai water heater codes
All Rinnai water heater error codes →
Other water heater brands: Rheem · Ruud · Navien · Noritz · Takagi · A.O. Smith · Bradford White · State / American · Generic electric · Generic tankless
This information may contain errors or not apply to your exact model — always double-check it against your appliance's own manual before acting. If there's any chance of a gas, fire, electrical, carbon monoxide, or other safety hazard, stop and call a licensed professional or the appropriate agency (e.g. your gas utility) instead of relying on this page alone.