E981 on a Rinnai R290 monobloc: High pressure inverter
Short answer
On a Rinnai heat pump, E981 means: High pressure inverter. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: High pressure inverter.
Part involved: compressor / refrigerant circuit.
When it shows: Inverter high-pressure: auto-resets after pressure switch reset (140 s for 106/109/112, 30 s for 115/118).
Is it safe?
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: manual reset if >3 trips in one hour.
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
- Record high/low pressures, discharge/suction temperatures and EEV steps with the unit running.
- Check water-side flow and air-side coil (blocked/frosted fins).
- Check pressure switches/transducers and wiring.
- Leak-test the refrigerant circuit and correct the charge (F-gas / flammable-refrigerant competent engineer only).
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
- Maxa i-290 Inverter air/water heat pumps with axial fans - Controller Manual (0106-0118) ↗ · page p.44 (MAXA i-290 controller manual) · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026