- Boilers
- Gas boiler
F43
Cointra F43 on a gas boiler: heat exchanger protection
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Cointra F43 means the heat exchanger protection has acted because water is not circulating properly or there is air. It clears by itself. Check the gauge when cold reads close to 1 bar and, if F43 returns often, call the technician.
Safety first
Stop and check this first
- If you smell gas, forget F43: do not use switches or phones near the boiler, ventilate, close the gas tap if accessible, leave and call your gas distributor's emergency number from outside. Cointra says to switch a faulty boiler off.
- Do not ask for the heat exchanger protection to be disabled so F43 stops showing: there is a parameter for it, but the code is warning that water is not circulating properly.
Safe checks you can perform
- Display indication and whether it clears
- Pressure on the gauge
- When it started
- Circulator and bleeding by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Circulator check
- Do not attempt this professional task: Bleeding and protection parameter check
- Do not attempt this professional task: History after the repair
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.
Circulator check
What they doThe technician checks that the circulation pump is not seized and reads its current speed in the Information menu with the heating calling.
They must show youthe pump running and its speed on the display.
In writingthe pump condition and, if replaced, the reference and reason.
Bleeding and protection parameter check
What they doThe technician bleeds the system, checks the expansion vessel charge and checks the heat exchanger protection parameter, which can disable F43.
They must show youthe parameter value before and after.
In writingthat the protection is still active and what was corrected.
History after the repair
What they doAfter bleeding or repairing, the technician checks the History menu and leaves the boiler running on heating to see whether F43 returns.
They must show youthe history and the boiler running without F43.
In writingthe earlier codes and the test result.
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.
Display indication and whether it clears
- Who:
- you.
- How:
- watch the display without pressing anything; Cointra says the multifunction indicator flashes during heat exchanger protection and that F faults clear by themselves.
- Result that matters:
- whether F43 goes away and the boiler resumes.
- If it goes away:
- note when it appeared and whether the boiler was on heating or hot water.
- If it appears at every start:
- circulation has a problem that does not fix itself.
- Evidence to keep:
- a note of times and frequency.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Pressure on the gauge
- Who:
- you.
- How:
- read the gauge with the system cold. Cointra wants about 1 bar and says to restore it if it falls below 0.8 bar.
- Result that matters:
- whether the pressure is where it should be.
- If it is below 0.8 bar:
- open the filling key anticlockwise up to 1 bar, close it and let the Fh purge finish.
- If it is fine:
- pressure is not the cause; the circulator and air remain.
- Evidence to keep:
- a photo of the gauge after topping up.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
When it started
- Who:
- you.
- How:
- think back to whether F43 started after topping up, after changing or draining a radiator or after building work on the system.
- Result that matters:
- whether air may have got in recently.
- If it matches a top up or building work:
- air is the most likely explanation; tell the technician.
- If nothing like that happened:
- the circulator becomes more likely.
- Evidence to keep:
- the date of the top up or work.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Circulator and bleeding by the technician
- Who:
- authorised technician.
- How:
- checks that the pump is not seized, its speed and the expansion vessel, and bleeds air from the system and the boiler.
- Result that matters:
- whether water flows through the heat exchanger normally again.
- If the pump is sluggish or seized:
- it is freed or replaced.
- If air comes out when bleeding and F43 stops:
- air is confirmed.
- Evidence to keep:
- a report of the work done.
The circulator is inside the boiler and removing it means cutting power, closing the gas and draining the water. This is work for an authorised technician.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
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
- Boilers
- Brand
- Cointra
- Product type
- Gas boiler
Known code variants
- Anomalía F43 Ferroli
- Cointra F 43
- Error F43 Cointra
- Error F43 Ferroli
- F-43
- Ferroli error F43
- Ferroli F43
- Ferroli F43 boiler
- Ferroli F43 caldera
- Superlative F43
- Superlative Plus F43
What it means
In the Superlative Plus table, F43 is the heat exchanger protection acting. Among the board parameters, Cointra defines it by how fast the temperature rises, in degrees per second: if the water in the heat exchanger heats up too quickly, the boiler cuts out. During that function the multifunction indicator flashes. Cointra gives two causes, water not circulating and air in the system, and as an F fault it clears by itself. The code does not say which of the two is present.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas, forget F43: do not use switches or phones near the boiler, ventilate, close the gas tap if accessible, leave and call your gas distributor's emergency number from outside. Cointra says to switch a faulty boiler off.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Mediumeditorial warning
Do not ask for the heat exchanger protection to be disabled so F43 stops showing: there is a parameter for it, but the code is warning that water is not circulating properly.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Symptoms and causes
Probable causes · in order
- Water not circulatingPossible
Cointra says to check the circulator. With little flow, the heat exchanger heats very quickly and the board reads that sharp rise as a risk.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
- Air in the systemPossible
Cointra says to bleed the air. An air pocket in the heat exchanger leaves areas without water that heat up suddenly; it fits after topping up or draining.
Evidence: Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Virtual technician
Does F43 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
Cointra SUPERLATIVE PLUS 24 C, instrucciones de uso, instalación y mantenimiento
Cointra · 2017 · manual
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