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Heat pumps · Error codes · Rinnai
E641Rinnai

E641 on a Rinnai heat pump: Compressor discharge probe fault / high pressure switch trip

Short answer

On a Rinnai heat pump, E641 means: Compressor discharge probe fault / high pressure switch trip. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.

Reviewed 24 September 2026 · 2 sources

What it means

On the HPI (HPi32) R32 monobloc

The manual says: Compressor discharge probe fault / high pressure switch trip.

Part involved: temperature/pressure sensor.

When it shows: Also raised when the machine pressure switch exceeds 42.8 bar (R32); clears below 34 bar.

On the R290 monobloc (HPR290)

The manual says: Compressor discharge probe fault / high pressure switch trip.

Part involved: temperature/pressure sensor.

When it shows: Also raised when the pressure switch exceeds 30.5 bar; clears below 23 bar.

Is it safe?

Does the heat pump stop?Partly
Engineer needed?Yes

The heat pump keeps running with some functions stopped.

Resetting itself: unknown.

Manual reset: automatic.

What you can check

  • Note the code shown on the controller and the model number on the unit's rating label before contacting your installer.
  • Check that the heat pump's isolator and consumer-unit breaker are on; do not open any casing.

What the engineer will check

  • Check the sensor/probe connector and wiring.
  • Measure sensor resistance or transducer output against the manufacturer's table.
  • Replace the sensor or controller board as indicated.

Who to ask for: Heat pump engineer.

Certification: Heat pump installer competence; F-gas and flammable-refrigerant (R32/R290) handling competence for any refrigerant-circuit work.

What you might notice

Sources

A code explains what the controller detected, not a confirmed root cause.

Reviewed: 24 September 2026