Rinnai Error Code FL: Forced low-fire combustion (Tankless)
Rinnai error code FL on a tankless water heater means: Forced low-fire combustion. It is also called Rinnai diagnostic code FL.
Homeowner? What Rinnai code FL means for you
Usually minor Your tankless water heater is reporting: Forced low-fire combustion. This code is usually informational or minor. The safe checks below often clear it; call us if it keeps showing up.
Safe things you can check yourself
- Check that gas reaches the house: other gas appliances work, or the propane tank is not empty.
- Make sure the heater is plugged in and its breaker is on. In winter, keep the power on: it protects the unit from freezing.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the hot and cold water valves under the heater are fully open.
- If you have a remote controller, turn it off and on once. If the code comes back, call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Rinnai error code FL mean?
Forced Low combustion. Seen only during the gas pressure setting procedure that is done after certain components are replaced. Not part of normal use.
Applies to: Rinnai KCM tankless (RUCS65i/75i, RUS65e/75e) status monitor
Other Rinnai Tankless codes
All Rinnai Tankless Water Heater error codes →
Rinnai code FL: homeowner questions
What does Rinnai code FL mean?
Forced low-fire combustion. Forced Low combustion. Seen only during the gas pressure setting procedure that is done after certain components are replaced. Not part of normal use.
Is it safe to keep using my tankless water heater with code FL?
Usually yes. Code FL is normally minor, but if it keeps coming back have it checked.
Can I reset Rinnai code FL myself?
You can try one reset (power off for 30 seconds, then on). If Rinnai code FL comes back, the cause is still there and a licensed technician should check it.
Who can fix Rinnai code FL near me?
Aurora Star Tech Inc. repairs Rinnai tankless water heaters in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Tankless Water Heater No Hot Water: What to Check
Troubleshooting guides
- No hot water All brands · Tankless Water Heater
- Water temperature fluctuates All brands · Tankless Water Heater
- Checking PC board fuses and thermistors Rinnai · Tankless Water Heater
- Enter installer parameter mode (A button on the PC board) Rinnai · Tankless Water Heater
- First power-up setup: gas type and indoor/outdoor (RX/CX) Rinnai · Tankless Water Heater
- Lock or unlock the controller (key symbol) Rinnai · Tankless Water Heater
- Lock or unlock the KCM controller (LOC) Rinnai · Tankless Water Heater
- Performance data readout (items 01 to 24) Rinnai · Tankless Water Heater
- Reset after cleaning the venturi or replacing the gas valve (codes 17 / 52) Rinnai · Tankless Water Heater
- Reset the Service Soon (SS) reminder Rinnai · Tankless Water Heater
- Show live flow and outlet temperature on the KCM controller Rinnai · Tankless Water Heater
- Show the last 9 stored codes (diagnostic history) Rinnai · Tankless Water Heater
- Start descaling (vinegar flush) mode on the PC board Rinnai · Tankless Water Heater
- Switch the controller between Celsius and Fahrenheit Rinnai · Tankless Water Heater
- Turn controller key beeps on or off Rinnai · Tankless Water Heater
- Weak or missing flame signal (flame rod checks) Rinnai · Tankless Water Heater
Source: Rinnai KCM Series Manual (U328-0700X04), Diagnostic Information (status monitor) p.56. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.