- Heat pumps
- Pool heat pump
ER03
Zodiac Er03 on pool heat pump: lack of water flow
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
On the Zodiac Z250, Er03 means lack or absence of water flow in the heat exchanger. Check that the filter pump is running, the filter is not clogged and the by-pass valves are set the way the installer left them.
Safety first
Stop and check this first
- Water and electricity: switch off the heat pump supply before any cleaning or inspection. Zodiac warns of a risk of electric shock.
- Do not leave the heat pump trying to run without water flowing and do not defeat its safety devices: Zodiac states that disabling or by-passing a safety mechanism voids the warranty.
Safe checks you can perform
- Filter pump running
- Filter and water circuit clean
- By-pass valves in position
- Clearing the fault after 3 alerts
Leave these tasks to a qualified professional
- Do not attempt this professional task: Measuring the real flow
- Do not attempt this professional task: Checking the flow sensor and its connection
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.
Measuring the real flow
What they doThe technician checks that the flow through the heat pump is within the minimum and maximum range Zodiac gives for your model in the technical data, and resets the by-pass with the filter pressure rule.
They must show youthe measured flow or filter pressure against the manual figure for your model.
In writingthe flow found, the final valve positions and whether the code cleared.
Checking the flow sensor and its connection
What they doWith the unit isolated, the technician checks the connection of the sensor that detects flow and reconnects or replaces it, as Zodiac indicates for Er03.
They must show youthe checked connector and the unit starting without Er03 at normal flow.
In writingwhether the sensor was reconnected or replaced, with its part number and the reason.
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
- Who:
- you, no tools.
- How:
- check that the filter pump is running and that water returns to the pool through the return jets. Zodiac notes that if flow is zero or not enough, the heat pump stops.
- Result that matters:
- water circulating while the heat pump is trying to heat.
- If filtration was off or paused by a timer:
- switch it on and wait for the unit to restart.
- If filtration runs and the code stays:
- check the filter and the by-pass.
- Evidence to keep:
- time Er03 appeared and whether filtration was running.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
Filter and water circuit clean
- Who:
- you, no tools.
- How:
- empty the skimmer and pump pre-filter baskets and look at the filter pressure gauge; if it reads higher than usual, clean or backwash the filter following its instructions. Zodiac asks you to clean the pool and water circuit regularly.
- Result that matters:
- a clean filter and the filter pressure back at its usual value.
- If the filter was clogged and after cleaning the code does not return:
- it was lack of flow.
- If the filter is clean and the code returns:
- check the by-pass valves.
- Evidence to keep:
- filter gauge reading before and after cleaning.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
By-pass valves in position
- Who:
- you, looking only; fine adjustment is for the installer.
- How:
- look at the heat pump inlet, outlet and by-pass valves. Zodiac says to open inlet and outlet fully and close the by-pass valve gradually until filter pressure rises by 150 g (0.150 bar).
- Result that matters:
- inlet and outlet open and the by-pass only partly closed, with nobody having moved them.
- If a valve was closed or moved:
- put it back as it was set or ask the installer to readjust it.
- If the valves are right and Er03 continues:
- a technician is needed.
- Evidence to keep:
- photo of the three valves as you found them.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
Clearing the fault after 3 alerts
- Who:
- you, from the heat pump isolator, without opening it.
- How:
- if Er03 has appeared 3 times in 30 minutes, Zodiac says to unplug the heat pump for 2 minutes to clear the error. Do it only after water circulation is back.
- Result that matters:
- the unit starting and heating without showing Er03 again.
- If it starts and the code does not return:
- the cause was flow and it is solved.
- If it returns although water flows:
- the sensor or its connection needs a technician.
- Evidence to keep:
- how many times it appeared and the time between alerts.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
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
- Zodiac
- Product type
- Pool heat pump
Known code variants
- bomba de calor Zodiac sin caudal
- E03
- Er 03
- Poolex 03
- Poolex E03
- Poolex error 03
- Poolex fallo sensor de caudal
- Poolex flow sensor fault
- Poolex Jetline Selection Fi 03
- Zodiac Er03
- Zodiac heat pump lack of water flow
- Zodiac Z250 Er03
- Zodiac Z250 falta de caudal de agua
- Zodiac Z250 no water flow
What it means
Zodiac defines Er03 as lack or absence of water flow. The controller stops the unit when the water passing through the heat exchanger is zero or not enough. The manual gives two causes: too little water in the exchanger, from the filtration circuit or the by-pass valves, or a sensor that is disconnected or faulty. That is why the code does not point to one part: first you need to know whether water is really flowing. If the fault appears 3 times in 30 minutes, Zodiac says to unplug the heat pump for 2 minutes to clear it.
Warnings and stop conditions
- Highsource verified
Water and electricity: switch off the heat pump supply before any cleaning or inspection. Zodiac warns of a risk of electric shock.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
- Mediumsource verified
Do not leave the heat pump trying to run without water flowing and do not defeat its safety devices: Zodiac states that disabling or by-passing a safety mechanism voids the warranty.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
Symptoms and causes
Probable causes · in order
- Too little water in the exchangerCommon
The filter pump is stopped, the filter is dirty or the circuit does not carry enough water; once circulation is back, the code clears.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
- By-pass set wronglyCommon
The by-pass valve is too open or the inlet and outlet valves are closed, so water skips the heat pump; Zodiac warns that a wrong by-pass setting can make it malfunction.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
- Sensor disconnected or faultyPossible
Water flows normally but the sensor does not detect it; this is only confirmed when a technician checks the connection and sensor with the unit isolated.
Evidence: Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
Virtual technician
Does ER03 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
Zodiac Z250 heat pump: instructions for installation and use (H0791500 Rev B)
Zodiac Pool Care Europe (Fluidra) · 2023 · official_doc
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