CH14 on a LG heat pump: Water flow problem – low flow detected during pump operation (flow sensor models) or flow switch open while the internal pump runs / closed while it is stopped (flow switch models)
Short answer
On a LG heat pump, CH14 means: Water flow problem – low flow detected during pump operation (flow sensor models) or flow switch open while the internal pump runs / closed while it is stopped (flow switch models). 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 flow problem – low flow detected during pump operation (flow sensor models) or flow switch open while the internal pump runs / closed while it is stopped (flow switch models).
Part involved: flow sensor / flow switch, circulation pump, strainer.
When it shows: Flow switch models: switch open while pump running (or closed while stopped) for 15 s. Flow sensor models (split indoor 5 series, Hydrosplit, R290, IWT R32): flow <= minimum for 15 s during pump operation (7 LPM for 5-9 kW, 15 LPM for 12-16 kW) or outside 7-80 LPM range.
Likely causes:
- Low flow due to water leakage/low pressure; strainer or water pipe clogged; valves closed; air in the circuit; poor setting of external pump; circulation pump malfunction; flow sensor/flow switch disconnection, short or failure; PCB pump output 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.
Resetting itself: no.
Manual reset: Service-engineer repair and restart required (LG: resumed only after certificated professional's check).
What you can check
- Read the code on the controller (LG shows 'CH' + number; older wired controllers alternate 'CH' and the number) and note it together with the model number. Report it to your installer or an LG-authorised service centre – LG owner's manuals say an error code generated by self-diagnosis is a reason to call the service. This is an 'Error'-class fault: LG says the system can only be resumed after a qualified professional has checked it, so do not keep trying to restart it. Look at the system pressure gauge and tell the engineer what it reads (LG commissioning guidance is roughly 1.5–2.5 bar when cold); do not top up or bleed the system yourself unless your installer has shown you how, and make sure any filling loop is closed. If your installer fitted isolating valves or a magnetic filter, check any valves you normally operate are open.
What the engineer will check
- Check actual flow on the controller monitoring screen, leaks and system pressure, strainer (isolate valves, remove and clean), open valves, bleed air via air vent, external pump settings, pump 230 V output at CN_PUMP during "pump operating", flow sensor supply 5 V and signal 0.5-3.5 V (CN_F_SENSOR); replace pump, flow sensor or PCB.
Who to ask for: Heating/heat pump engineer (wet-side hydraulics).
Certification: None statutory for sealed-system wet-side work; G3 unvented qualification if the DHW cylinder is worked on.
What you might notice
Sources
- AIR-TO-WATER HEAT PUMP SERVICE MANUAL (General) – R32 Hydrosplit, MFL68682007 ↗ · MFL68682007 · page 71, 85-90 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026