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Rinnai · Boiler troubleshooting

Insufficient hot water quantity

What is going on

Low DHW flow.

Likely causes

  • Hot and cold connections swapped
  • Wrong or dirty flow reducing valve
  • Scale in the plate heat exchanger

Check in this order

  1. Check connections (left hot, right cold).
  2. Check restrictor type and cleanliness; clean or replace.
  3. Descale or replace the plate heat exchanger if nothing else helps.

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.