Investigate Rheem heat-pump water-heater airflow alert

[CCOSTAN]

Summary

Track investigation of a reported Rheem heat-pump water-heater error that may involve insufficient airflow around the compressor. Joanna should use this issue to correlate the vendor notification with Home Assistant telemetry and document any required maintenance or software follow-up.

Current evidence

• Home Assistant shows the water heater operating in heat-pump mode.
• At review time the unit was running with the state reported as compressor running.
• Current health indicators were reported at 100% for tank and compressor health.
• Available hot water was 33% at review time.
• The 24-hour history contains repeated compressor cycles, one element-running state, and brief unavailable/off transitions affecting several Rheem entities.
• The alert counter reached 2 and remained at 2 after the transient unavailable periods.
• The exact vendor email was not found in the authenticated mailbox search, so the original alert wording remains unverified.

Investigation plan

1. Obtain the exact Rheem error code/message and timestamp from the vendor email or device/app history.
2. Correlate that timestamp with compressor state, alert count, available-hot-water level, and any Home Assistant connectivity gaps.
3. Verify the physical airflow path: intake/exhaust clearance, filter or screen condition, evaporator/fan cleanliness, and condensate/drain path.
4. Determine whether the alert indicates a maintenance condition, a sensor/connectivity issue, or a genuine compressor/airflow fault.
5. Decide whether Joanna/Home Assistant needs a software improvement, such as preserving the vendor error text, alert code, timestamp, and a compact diagnostic snapshot.
6. Document the final resolution and any maintenance performed.

Guardrails

• Read-only troubleshooting and documentation first.
• No Home Assistant configuration, automation, device, or service changes in this issue until the evidence is confirmed.
• Treat current 100% health values as telemetry, not proof that airflow is normal.
• Keep household-specific identifiers and private infrastructure details out of public issue text.

[CCOSTAN]

Rheem diagnosis and temporary mitigation

Rheem confirmed the A005 alert and compressor fallback during guided troubleshooting.

• Entered the front-panel test menu with MODE + NEXT and reviewed compressor operation, thermistor temperatures, airflow temperatures, and current.
• Rheem diagnosed a failed evaporator thermistor (the gray-wire sensor at the back/bottom of the compressor cavity) because the evaporator reading remained too high.
• The air filter had mold present; it was washed, air-dried, and reinstalled.
• Rheem is overnighting the replacement sensor at no charge under the 10-year warranty.
• Rheem explicitly advised keeping the heater in Electric mode until the repair to avoid possible compressor damage.

Home Assistant has also been temporarily protected:

• The live water heater is confirmed in Electric mode.
• The Powerwall outage automation's daytime recovery branch now selects Electric instead of Heat Pump.
• A temporary guard reloads on startup, watches mode changes, and checks every 15 minutes. It forces any compressor-capable mode back to Electric, while still allowing Off during outage load shedding.
• The configuration passed the full Home Assistant config check and the guard is loaded/enabled.

Post-repair validation remains:

1. Replace the evaporator thermistor.
2. Check/relocate the ambient thermistor away from the compressor and refrigerant piping per Rheem's bulletin.
3. Rerun the thermistor test and confirm the evaporator reading stabilizes below 70°F.
4. Confirm A005 does not return and Home Assistant returns from element fallback to normal compressor operation.
5. Remove the temporary Electric-mode guard and restore the normal Powerwall Heat Pump behavior.

Leaving this issue open until the part is installed and those checks pass.