- Heat pumps
- Pool heat pump
ER11
Poolex Er 11 on pool heat pump: water temperature gap too big
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On the Poolex Jetline Selection Fi, code 11 means the difference between inlet and outlet water temperature is too big, due to low water flow. Check the filtration, the filter and the by-pass valves.
Safety first
Stop and check this first
- If the 11 keeps coming back, switching off and on without fixing the flow only hides it: the unit keeps running with too little water in the heat exchanger.
- Poolex requires the power supply to be disconnected before any work or maintenance on the heat pump. Do not open the casing: water and mains voltage are together inside.
Safe checks you can perform
- Filter pump running and water in the pool
- By-pass valves
- Clean pool filter
- Status values and fault history
Leave these tasks to a qualified professional
- Do not attempt this professional task: Cross-checking the water sensors
- Do not attempt this professional task: Measuring the real flow
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.
Cross-checking the water sensors
What they doIf the flow is correct and the 11 returns, the technician compares the F3 and F4 readings with a reference thermometer at the inlet and outlet.
They must show youF3 and F4 against the reference thermometer.
In writingthe measured values and the sensor replaced, if any, with its reference.
Measuring the real flow
What they doThe technician measures the flow through the heat pump and compares it with the minimum and maximum for your model in the manual's specification table.
They must show youthe measured flow against the minimum and maximum for your model.
In writingthe measured flow and the valve or filtration adjustment made.
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.
Filter pump running and water in the pool
- Who:
- you, without tools.
- How:
- confirm the filter pump is running, the pool water level is normal and water returns to the pool; if the circulating pump is wired to terminals P1 and P2, the heat pump starts it itself. Poolex says never to start the unit with no water in the pool or with the circulating pump stopped.
- Result that matters:
- water flowing through the heat pump while it is on.
- If the filtration was stopped or paused by its timer:
- start it and see whether the code clears.
- If the filtration runs normally:
- move on to the by-pass valves.
- Evidence to keep:
- the filtration timer setting and a photo of the water return.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
By-pass valves
- Who:
- you, without tools.
- How:
- the by-pass is 3 valves that regulate the water going through the heat pump. Compare their position with the diagram in section 3.6 of the manual, which marks which valves are open and which one is half open, and correct any that does not match.
- Result that matters:
- inlet and outlet valves open and the by-pass valve set as the diagram shows.
- If one was closed or badly set:
- correct it and see whether the code clears.
- If they match the diagram:
- check the filter.
- Evidence to keep:
- a photo of the 3 valves before and after touching anything.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
Clean pool filter
- Who:
- you, with the filtration stopped as your filter's instructions say.
- How:
- clean or backwash the filter upstream of the heat pump. Poolex asks you to check the water flow every month and clean the filter if needed, because a dirty filter causes operating problems.
- Result that matters:
- a stronger return flow with a clean filter.
- If the filter was dirty and the code does not come back:
- the cause was low flow.
- If the filter was clean or the code comes back:
- call a technician.
- Evidence to keep:
- the cleaning date and a photo of the filter.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
Status values and fault history
- Who:
- you, from the heat pump controller.
- How:
- enter status check mode by holding for 3 seconds the button shown in section 5.9 of the manual; step through the parameters and note the inlet (F3) and outlet (F4) water temperatures and codes HE1 to HE4 (fault history).
- Result that matters:
- knowing whether the code repeats in the history and which values the unit showed.
- If the history shows the same code several times:
- it is not a one off; show it to the technician.
- If it is the first time and it clears once the water is corrected:
- watch it for a few days before calling.
- Evidence to keep:
- a photo of each value on the screen, with the date.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
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
- Poolex
- Product type
- Pool heat pump
Known code variants
- Er 11
- Poolex 11
- Poolex diferencia temperatura entrada salida
- Poolex E11
- Poolex error 11
- Poolex inlet outlet temperature difference
- Poolex Jetline Selection Fi 11
What it means
The controller compares the inlet water sensor with the outlet sensor. If water leaves much hotter than it enters, too little water is going through the heat exchanger. Poolex gives a single cause for 11 on the Jetline Selection Fi: insufficient water flow. The code clears by itself after three minutes and the unit restarts; if it appears three times, the unit must be switched off to clear it. It does not mean a sensor has failed: it shows the water is not circulating enough.
Warnings and stop conditions
- Mediumeditorial warning
If the 11 keeps coming back, switching off and on without fixing the flow only hides it: the unit keeps running with too little water in the heat exchanger.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
- Highsource verified
Poolex requires the power supply to be disconnected before any work or maintenance on the heat pump. Do not open the casing: water and mains voltage are together inside.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
Symptoms and causes
Probable causes · in order
- Filtration stopped or intermittentCommon
The filter pump stops or runs at low output while the heat pump is working. You can see it on the timer and at the return.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
- By-pass diverting too much waterCommon
The inlet or outlet valves are half closed or the by-pass valve is too open, so little water enters the heat pump.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
- Dirty filterPossible
The filter upstream of the heat pump is clogged and restricts flow even with the valves set correctly. It improves once cleaned.
Evidence: Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
Virtual technician
Does ER11 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
Poolex Jetline Selection Fi: installation and user manual (multilingual, 08-2025)
Poolstar (Poolex) · 2025 · official_doc
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