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HTP Error Code FL: Low water flow (Boiler)

Updated · by Aurora Star Tech Inc.

HTP error code FL on a boiler means: Low water flow. It is also called HTP diagnostic code FL.

Low severityBoilerElite EL

Homeowner? What HTP code FL means for you

Usually minor Your boiler is reporting: Low water flow. 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 the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
  • Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
  • Look at the pressure gauge on the boiler. If it reads much lower than usual or near zero, or water is leaking, call a technician.
  • Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
  • Check that the boiler gas valve is open (handle in line with the pipe).
  • Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.

Call (647) 657-2977Book a service call

Licensed technicians serving Vaughan, Toronto and the GTA.

What does HTP error code FL mean?

Flow switch shows too little flow; pump on.

Applies to: EL-80, EL-110, EL-150, EL-220, EL-299, EL-399 (N/LP)

Common causes of HTP code FL

  • Flow switch problem. Note: this model has no flow switch, so this code is for other HTP products.
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.

HTP models that use code FL

EL-80 LPEL-80 NEL-110 LPEL-110 NEL-150 LPEL-150 NEL-220 LPEL-220 NEL-299 LPEL-299 NEL-399 LPEL-399 N

Other HTP Boiler codes

CodeMeaning
F09No flame on ignition
F10Flame loss
F11False flame signal
F13Fan speed error
F20Condensate full
F31Program error
FLUHigh flue pressure
FOUOutdoor sensor fault
GAS VALVE ON / RUNIgnition then run status
LOCKOUTLockout (display message)
LOU24 volt supply low
MAINTENANCE REQUIREDService reminder

All HTP Boiler error codes →

HTP code FL: homeowner questions

What does HTP code FL mean?

Low water flow. Flow switch shows too little flow; pump on.

Is it safe to keep using my boiler with code FL?

Usually yes. Code FL is normally minor, but if it keeps coming back have it checked.

Can I reset HTP code FL myself?

You can try one reset (power off for 30 seconds, then on). If HTP code FL comes back, the cause is still there and a licensed technician should check it.

Who can fix HTP code FL near me?

Aurora Star Tech Inc. repairs HTP boilers in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.

Homeowner help: Boiler Not Heating: What to Check

Troubleshooting guides

Source: Elite EL-80 N Installation Manual (LP-293), p. 68. 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.

Emergency Boiler Repair

647-657-2977