Rinnai · Boiler

FILL Water pressure low / system empty

Normal status E-Combi (E50CRNE75CRN/E75CRPE110CRN/E110CRP)

What the display is showing

Shown when the system is empty or pressure is below 10 PSI; the boiler stays out of service until topped up. Flashing FILL alternating with the pressure value (below 12 PSI) means reduced 50% power operation is possible.

Applies to: E50CRN; E75CRN; E75CRP; E110CRN; E110CRP

What to do

Fill to 16-18 PSI cold
Press STEP briefly to show P XX (pressure)

Other codes on the same units

COdE Access code entry
Copy Factory settings restored
ERRO Error chapter
FUSE 24 V fuse defective
Good Good state (normal)
Green button reset Restore factory parameters
HIGH Water pressure too high
INFO Information chapter

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Source: Rinnai E-Combi Series Installation & Servicing Instructions (8U516009 V0116), p.50-54 (8, 9.2). Summarized in our own words; check the original manual for your model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.