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Rinnai · Combi boiler

700 PC Board fault

High severity I-Series Plus 150K and smallerI-Series Plus 175K and higher

What the control is telling you

General fault of the main PC Board or its connections.

Applies to: I-Series Plus boilers — 150K BTU and smaller and 175K BTU and higher (Combi and Solo)

Likely causes

  • Loose, damaged or broken connectors/wiring
  • Moisture or corrosion on board connectors
  • Incorrect supply voltage
  • Poor grounding
  • Incorrect parameter settings or outdated board version
  • Failed PC Board

Test and repair steps

  1. Check all PC Board connectors for loose, damaged or broken connections and replace any defective wiring or harness.
  2. Look for moisture or corrosion on connectors, harnesses and pins; replace corroded parts and fix the moisture source.
  3. Confirm correct supply voltage to the board and that the unit is properly grounded.
  4. Confirm all parameters are set correctly and that the PC Board is the latest version.
  5. Replace the PC Board.
  6. Before swapping the PC Board, write down all parameter settings, then copy them from the old board using the data transfer cable supplied with the new board (see the part's instructions).
  7. If data transfer fails, re-program all parameters and set gas valve values per the Installation and Operation Manual (150K and smaller: also see docs 800000253 and 800000254).

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Source: Rinnai Troubleshooting I-Series Plus Boiler Diagnostic Codes (800000375), p.39. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

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.