LG CH14 Error Code Explained

If your LG heat pump is showing a CH14 fault code, the most important thing to understand straight away is that this error does not automatically mean your heat pump has failed. CH14 is one of the most common fault codes we see on LG heat pump systems, and in the majority of cases the heat pump itself is not the problem the issue lies elsewhere within the heating system.

CH14 is a flow protection fault. It means the heat pump cannot detect sufficient water circulation through the heating circuit to operate safely. Heat pumps depend on a constant, adequate flow of water to move heat around the property. When the flow rate drops below the threshold the system needs, the heat pump protects itself by shutting down and displaying the CH14 code. The fault code tells you there is a circulation problem but it does not tell you what is causing it, and that distinction matters enormously before any parts are ordered or replaced. Our article on why your heat pump shows a flow error explains the broader mechanics of flow faults in detail and is worth reading alongside this guide.

The most common causes of a CH14 fault are things that restrict water circulation rather than anything to do with the heat pump refrigerant circuit or the compressor. A blocked or dirty magnetic filter is one of the most frequent culprits debris and magnetite build up gradually over time, and once the filter is sufficiently blocked it can restrict flow enough to trigger the fault. Our article on how dirty filters can cause heat pump problems explains exactly how this happens and what to check. Blocked inline strainers cause the same effect and are often overlooked during routine maintenance. Air trapped within the system is another common cause air pockets disrupt circulation and can prevent the heat pump from seeing the flow it needs, particularly after the system has been drained or topped up. Low system pressure can also contribute to flow problems, and if your pressure gauge is reading below 1 bar our guide on why your heat pump keeps losing pressure covers what to check.

Closed or partially closed valves are a surprisingly common cause that is easy to miss. Valves are frequently left partially closed after maintenance work sometimes by the homeowner, sometimes by a trades person who visited for a different reason and the effect on circulation can be significant. It is worth checking every valve in the system is fully open before assuming the fault is more complex. Similarly, thermostatic radiator valves that have been turned down or fully closed on too many radiators can reduce the flow the heat pump sees to the point where CH14 triggers. Heat pumps need water to circulate continuously, and when a large proportion of the emitters are closed off, the system struggles to maintain adequate flow. Our article on should you use TRVs with a heat pump explains how TRVs interact with heat pump circulation and what best practice looks like. For systems with lots of separate zones, the zoning design itself can be the underlying cause a pattern we have seen cause persistent flow faults and short cycling, as detailed in our heat pump short cycling and zoning design issue case study.

Circulation pump faults and incorrect pump settings are also worth investigating. If the pump speed has been set too low during commissioning, or if the pump itself has a fault, the system will not achieve the flow the heat pump requires even with everything else in order. Commissioning errors in general are a common root cause of flow problems that appear months after installation the system works adequately in milder conditions but can't maintain flow when demand increases in cold weather. Our guide on common commissioning mistakes with air source heat pumps covers the most frequently missed setup errors in detail.

One of the reasons CH14 appears regularly on systems that have been running without problems for a period of time is that many of these causes develop gradually. Debris builds up slowly in filters and strainers. Air accumulates incrementally. Valves get partially adjusted. Homeowners turn TRVs down room by room over a winter. No single change triggers the fault immediately, but the cumulative reduction in flow eventually reaches the point where the heat pump can no longer maintain the circulation it needs. When that happens, CH14 is the result and it often appears on a cold morning when the system is working hardest, which can make it feel like a sudden failure when in reality it has been approaching that threshold for some time.

It is important not to replace parts particularly pumps, sensors, or the heat pump itself before the actual cause of the flow restriction has been confirmed. We have reviewed cases where significant money was spent on replacement components when the underlying issue turned out to be a blocked filter, a closed valve, or a commissioning error that took minutes to correct once identified. Our Fix My Heat Pump service can help identify whether a CH14 fault is a simple flow restriction, a commissioning problem, or something requiring further investigation — often via a video call where we can review the system, the settings, the filter condition, the pump configuration, and the pipework arrangement together. If you have a plumber or heating engineer who works on your system but does not specialise in heat pumps day to day, we are also happy to work directly alongside them. A second opinion from someone who sees these faults regularly can often identify the cause very quickly. For homeowners planning an installation who want to avoid these issues from the outset, our Pre-Installation Design and Heat Loss Review covers system design including pipework, zoning, pump sizing, and filter placement before any work begins.