- Boilers
- Gas boiler
F43
Ferroli F43 on a gas boiler: exchanger protection
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
The boiler tripped the exchanger protection because water is not circulating properly. It is an F code that clears on its own when conditions return to normal. Check the gauge pressure with the system cold and, if F43 repeats, call the technician.
Safety first
Stop and check this first
- If F43 appears often, do not leave the boiler struggling: lack of circulation is what trips the exchanger protection, and a technician should check it.
- If you smell gas: do not switch lights or appliances on or off, do not use flames or a phone indoors, open doors and windows if you can on your way out, leave the home and call your gas supplier's emergency number or the emergency services from outside.
Safe checks you can perform
- Your exact Ferroli boiler model
- Pressure gauge with the system cold
- Whether F43 clears on its own or repeats
- Inspection by a qualified gas technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Check the circulating pump
- Do not attempt this professional task: Vent the system
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 circulating pump
What they doThe technician verifies that the circulating pump runs and moves water through the circuit.
They must show youthe pump running.
In writingits condition and whether it was replaced.
Vent the system
What they doThe technician vents air from the heating circuit and checks the final cold pressure.
They must show youthe final pressure.
In writingthat the system was vented and the 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.
Your exact Ferroli boiler model
- Who:
- you.
- How:
- find the model name on the front or on the rating plate, without opening the casing, and compare it with your boiler's manual.
- Result that matters:
- confirming what F43 means on your model.
- If it is a DIVAtop MICRO LN F or BLUEHELIX TECH RRT 28 C:
- F43 is the exchanger protection.
- If it is another model:
- check the fault table in its manual before following this page.
- Evidence to keep:
- photo of the rating plate and of the code.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento
Pressure gauge with the system cold
- Who:
- you.
- How:
- with the heating cold, read the pressure gauge at the bottom of the boiler or the display. Ferroli gives a filling pressure of approx. 1 bar with the system cold.
- Result that matters:
- whether the pressure is at its value or below it.
- If it is low:
- follow the Ferroli F37 page to top up with the filling cock and close it afterwards; a system short of water may not circulate properly.
- If it is correct:
- low pressure does not explain F43; move on to the next check.
- Evidence to keep:
- dated photo of the gauge.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento
Whether F43 clears on its own or repeats
- Who:
- you.
- How:
- wait and watch the display; Ferroli says F codes reset automatically as soon as the value returns within the normal range.
- Result that matters:
- whether F43 repeats.
- If it clears and does not return:
- note when it happened.
- If it repeats:
- circulation is still failing; call the technician.
- Evidence to keep:
- photo of the code with the time.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento
Inspection by a qualified gas technician
- Who:
- a qualified gas technician, preferably from Ferroli's service network.
- How:
- checks that the circulating pump works and vents the air from the system.
- Result that matters:
- which branch of Ferroli's fault table is confirmed by measurements.
- If the cause is found:
- they should explain which measurement confirms it before replacing parts.
- If everything measures correctly and the code returns:
- they should move to the next cause in the table, not replace parts at random.
- Evidence to keep:
- job sheet with the measurements and parts replaced.
Opening the casing or touching the gas valve, electrode, burner or flue is work for the technician only. Ferroli says to disconnect the electrical power supply and close the gas cock upstream before any operation inside the boiler.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 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
- Ferroli
- 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
On the DIVAtop MICRO LN F and the BLUEHELIX TECH RRT 28 C, Ferroli defines F43 as exchanger protection activation. The causes in the table are no water circulation in the system, so the circulating pump must be checked, and air in the system, which must be vented. It is an F code, a temporary shutdown. The code does not tell a pump fault from air or another restriction in the circuit.
Warnings and stop conditions
- Mediumeditorial warning
If F43 appears often, do not leave the boiler struggling: lack of circulation is what trips the exchanger protection, and a technician should check it.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento
- Criticaleditorial warning
If you smell gas: do not switch lights or appliances on or off, do not use flames or a phone indoors, open doors and windows if you can on your way out, leave the home and call your gas supplier's emergency number or the emergency services from outside.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Symptoms and causes
Probable causes · in order
- No water circulation in the systemPossible
Ferroli says to check the circulating pump. It fits if the radiators do not heat up.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento
- Air in the systemPossible
Ferroli says to vent it. It fits after topping up water, a repair or air noises in the pipes.
Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 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
Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento
Ferroli · 2015 · manual
- 2
Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento
Ferroli · 2018 · manual
Was this entry useful?