Rinnai RH180 Installation Fundamentals page 54

Maintenance Codes
Code Definition
FE Flammable Vapors
Cont. Detected.
14 Thermal Fuse.
54
Remedy
When safety personnel have identified the area as safe and all flammable
vapors have been removed and eliminated, the water heater can be reset by
unplugging the unit and then plugging back in.
If "FE" continues to flash after the area is determined to be free from
flammable vapors, contact a qualified service technician.
Check for restrictions in air flow around the unit and vent termination.
Licensed
Check gas type of unit and ensure it matches the gas type being used.
professional
Ensure dip switches are set to the proper position.
only
Check for foreign materials in combustion chamber and/or exhaust piping.
Check heat exchanger for cracks and/or separations.
Check heat exchanger surface for hot spots which indicate blockage due to
scale buildup. Refer to heat exchanger flushing instructions in the manual.
Measure the resistance of the safety circuit.
Ensure high fire and low fire manifold pressure is correct.
Check for improper gas type conversion of the product.