CH04 on a LG THERMA V Water Heater: Condensate drain is blocked (THERMA V water heater)
Short answer
On a LG heat pump, CH04 means: Condensate drain is blocked (THERMA V water heater). The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Condensate drain is blocked (THERMA V water heater).
Part involved: condensate drain.
When it shows: Condensate drain is blocked.
Likely causes:
- Condensate drain is blocked.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: unknown.
Manual reset: Per LG corrective action; service engineer for most codes.
What you can check
- LG's corrective action: clean the condensate drain (see the owner's manual 'Condensate Drain Maintenance' section) – clear visible debris from the external drain hose/outlet only; call support if the code persists. While the fault is present the unit operates as: Use elements only – hot water will be heated more slowly/at higher cost.
What the engineer will check
- Clear condensate drain and trap; check drain pan and float/detection.
Who to ask for: Heat pump engineer / electrician (inverter and PCB diagnostics).
Certification: Competent person for electrical work (BS 7671); isolate and wait 3 min for DC-link discharge.
What you might notice
Sources
- LG Heat Pump Water Heater Owner's Manual WH20S F5 / WH27S F5 (EU/UK multilingual), MFL71409209 Rev.00 (2023) – ManualsLib 3195149 ↗ · MFL71409209 Rev.00_090823 · page 32 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026