H20 on a Panasonic heat pump: Water pump abnormality
Short answer
On a Panasonic heat pump, H20 means: Water pump abnormality. 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: Water pump abnormality.
Part involved: Water (circulation) pump; indoor PCB.
When it shows: During startup and operation of cooling and heating, the rotation speed detected by the IPM of water pump motor during water pump operation is used to determine abnormal water pump (feedback of rotation > 6,000rpm or < 700rpm). Service-manual table judgement: Continue for 10 sec. (L, K, J MDC, J MXC, J AIO, H, F).
Likely causes:
- 1 Operation stop due to short cir cuit inside the water pump motor winding. 2 Operation stop due to breaki ng of wire inside the water pump motor. 3 Operation stop due to breaki ng of water pump lead wires. 4 Operation stop due to water pump motor IPM malfunction. 5 Operation error due to faulty indoor unit PCB.
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: Not stated in the Panasonic documents opened; protection counters lock out after the stated number of occurrences.
Manual reset: User: 'Error Reset' in the remote-controller Quick Menu (H/J/K/L controllers) or OFF/ON; engineer must clear the underlying cause (service manuals: 'When error happens, the power has to be reset').
What you can check
- Read and note the code shown blinking on the remote controller (also stored under System Check > Error history). Per the Panasonic operating instructions the user may switch the system OFF/ON at the remote controller and use 'Error Reset' in the Quick Menu; if the code returns, leave the system and contact the installer (UK user guide lists Panasonic technical support as the fallback).
What the engineer will check
- Check water pump motor winding and lead wires; check pump feedback (rotation outside 1,000-6,000 rpm triggers fault); check indoor PCB pump drive; check pump for air lock or seizure.
Who to ask for: Heat pump / heating engineer (hydraulics).
Certification: None statutory for water-side work; G3 unvented-cylinder competence if cylinder safety devices are involved.
What you might notice
Sources
- Service Manual Hydromodule WH-SDC0509L3E5/L6E5 with WH-WDG05LE5/07LE5/09LE5 (Order No PAPAMY2307068CE) ↗ · PAPAMY2307068CE · page 189 (error codes table); 193 (self-diagnosis) · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026