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Rinnai · Boiler troubleshooting

DHW temperature drops

What is going on

Hot water temperature falls during use.

Likely causes

  • Hot and cold connections swapped
  • Wrong flow reducing valve
  • DHW power set too low
  • T3 sensor or wiring fault

Check in this order

  1. Check connections.
  2. Check restrictor type against the installation instructions.
  3. Check PARA parameter 43.
  4. Check DHW sensor T3 and wiring.

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

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Source: Rinnai E-Combi Series Installation & Servicing Instructions (8U516009 V0116), p.77 (15.4). Written in our own words; check the manual for your exact 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.