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Rinnai · Combi boiler

190 Electrical grounding / short in DC circuit

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

What the control is telling you

Code 190 (or 120) appearing right after water flow starts, with no flame in the burner box, indicates an electrical short in a component.

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

Likely causes

  • Shorted wiring harness
  • Shorted water flow control or bypass valve
  • Short in another component on the DC circuit

Test and repair steps

  1. Confirm the code appears immediately when water flow starts and no flame is visible in the burner box.
  2. Unplug one DC component at a time (harnesses, water flow control, bypass valve, etc.) and run the unit after each.
  3. When the unit tries to fire without code 120/190, the short is in the circuit last unplugged; repair or replace that component.

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Source: Rinnai Troubleshooting I-Series Plus Boiler Diagnostic Codes (800000375), p.13. 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.