P3 on an Ideal Heating HP290: Overcurrent Protection Error
Short answer
On an Ideal Heating heat pump, P3 means: Overcurrent Protection Error. The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Overcurrent Protection Error.
Part involved: compressor, inverter.
Likely causes:
- Supply voltage outside 207-253 V AC; inverter defective; compressor U/V/W wiring incorrect; compressor windings (<10 ohm) or mechanical failure; associated no-water-flow (E0/E8); HP switch pipe/filter blockage; EEV fault.
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.
Manual reset: Reset lockout (p.108).
What you can check
- Note the code or fault message shown on the controller/Halo and when it appeared; check the heat pump's isolator and consumer-unit breaker are on. Check whether lights or other appliances are also affected (possible supply problem) and whether any breaker/RCD has tripped - do not reset repeatedly.
What the engineer will check
- Check supply voltage; test inverter; check compressor wiring and winding resistances; check compressor for seizure/wear; check EEV; replace inverter or compressor.
Who to ask for: Heat pump engineer competent with R290 (A3, highly flammable); refrigerant-circuit work requires Cat I/II F-gas plus City & Guilds 6187-21 or equivalent (I&M p.93 warning).
Certification: F-gas Cat I/II + C&G 6187-21 (R290) for refrigerant work; electrical work by competent person.
Sources
- HP290 Monobloc Heat Pump System - Installation & Maintenance (UIN 240080 A09) ↗ · UIN 240080 A09 · page 108 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026