- Heat pumps
- Air-to-water heat pump
CH15
LG Therma V CH15 heat pump error: water pipe overheated
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
CH15 on an LG Therma V means the leaving water got hotter than allowed. Note what the unit was doing and the temperature shown on the controller, and call service so they can check the electric heater.
Safety first
Stop and check this first
- After CH15 the water in the pipes may be very hot: do not open air vents or valves, and leave any work on the water side to service staff.
- LG asks that safety devices are never changed or removed. Bypassing a temperature protection can lead to burns or a fire.
Safe checks you can perform
- Write down the operating mode
- Check the target water temperature
- Stop if there is a burning smell or loud noise
Leave these tasks to a qualified professional
- Do not attempt this professional task: Check the heater control
- Do not attempt this professional task: Check the thermal fuse and history
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Check the heater control
What they doThe technician reviews how the electric heater is switched on and whether it switches off when it should, following the LG manual.
They must show youthe recorded leaving temperature and the heater state during the test.
In writingwhat was found in the heater control and what was changed.
Check the thermal fuse and history
What they doThey also read the code history in case the thermal fuse warning appeared too, which LG links to the heater tank overheating beyond 80 °C.
They must show youthe error history and the condition of the thermal fuse.
In writingthe parts checked, those replaced and why.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Write down the operating mode
- Who:
- you, at the controller.
- How:
- note whether the unit was heating, making domestic hot water or running a special function such as screed drying, and the time CH15 appeared.
- Result that matters:
- giving the technician the context in which the water overheated.
- If it was using the backup heater, for example during screed drying:
- say so, it points straight at the heater.
- If it was in normal operation:
- mention that too.
- Evidence to keep:
- photo of the controller with the code and the active mode.
Evidence: LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
Check the target water temperature
- Who:
- you, only looking at the controller.
- How:
- look at the water temperature set for heating and for hot water. LG publishes a 15 to 65 °C water range for these models; do not change service settings.
- Result that matters:
- knowing whether the set values are sensible.
- If something looks unusual:
- leave it and mention it to the technician.
- If the values are normal:
- the technician should focus on the heater and its control.
- Evidence to keep:
- photo of the screen with the set temperatures.
Evidence: LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
Stop if there is a burning smell or loud noise
- Who:
- you.
- How:
- if the warning comes with a burning smell or a loud noise, LG asks you to stop the unit, turn the breaker off and not try to repair or restart it.
- Result that matters:
- avoiding further damage while service is on the way.
- If there is a smell or noise:
- switch off the breaker and call service at once.
- If there is nothing like that:
- call anyway, since a self diagnosis code calls for service.
- Evidence to keep:
- note of what you heard or smelled and when.
Evidence: LG air to water heat pump owner's manual MFL68026705
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Heat pumps
- Brand
- LG
- Product type
- Air-to-water heat pump
Known code variants
- aerotermia LG CH15
- bomba de calor LG CH15
- CH15
- error 15 LG Therma V
- LG air to water CH15
- LG heat pump CH15
- LG monobloc CH15
- LG Therma V CH15
- LG Therma V error 15
- LG Therma V tubería de agua sobrecalentada
- LG Therma V water pipe overheated
What it means
In the LG Therma V R32 Monobloc installation manual (2026, English only), display number 15 means water pipe overheated. LG puts it down to abnormal operation of the electric heater or leaving water above 72 °C, and adds that with correct heater control the leaving water should not exceed 72 °C. The working water range LG publishes for these models is 15 to 65 °C. This warning alone does not prove the heater is broken.
Warnings and stop conditions
- Mediumeditorial warning
After CH15 the water in the pipes may be very hot: do not open air vents or valves, and leave any work on the water side to service staff.
Evidence: LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
- Highsource verified
LG asks that safety devices are never changed or removed. Bypassing a temperature protection can lead to burns or a fire.
Evidence: LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
Symptoms and causes
Probable causes · in order
- Electric heater out of controlCommon
If the backup heater keeps heating when it should not, the leaving water climbs above normal and the protection trips.
Evidence: LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
- Leaving water above 72 °CPossible
LG sets 72 °C as the top leaving temperature with correct control; any situation that goes past it raises CH15.
Evidence: LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
Virtual technician
Does CH15 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
LG Therma V R32 Monobloc air to water heat pump installation manual MFL68026607
LG Electronics · 2026 · manual
- 2
LG air to water heat pump owner's manual MFL68026705
LG Electronics · 2026 · manual
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