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F37

Ferroli F37 on a gas boiler: incorrect system water pressure

Verified with sources3 sourcesReviewed Oct 3, 2026
Technician coming? See the 2 steps they must show you
Wall-mounted combi gas boiler installed in a home
Kai KemmannCC BY-SA 4.0Image source

Risk level

Medium

Proceed carefully and stop if the check is unclear.

Urgency

Medium

Quick answer

The heating water pressure is below the minimum and the boiler stops. With the system cold, top up with the filling cock to about 1 bar, as Ferroli says, and always close it afterwards.

Safety first

Stop and check this first

  • Topping up the boiler every few days is not normal: it indicates a water leak that a technician should trace.
  • Always close the filling cock afterwards: Ferroli asks for it explicitly. If the pressure goes too high, the DIVAtop shows another fault (F40) for high pressure.

Safe checks you can perform

  • Gauge reading with the system cold
  • Top up with the filling cock
  • If the pressure drops again
  • Inspection by a qualified gas technician

Leave these tasks to a qualified professional

  • Do not attempt this professional task: Check the water pressure switch or sensor
  • Do not attempt this professional task: Trace water leaks

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.

  1. Check the water pressure switch or sensor

    What they doThe technician verifies the connection and operation of the water pressure switch or sensor and its wiring.

    They must show youthe gauge pressure against the pressure the boiler reads.

    In writingthe condition of the switch or sensor and whether it was replaced.

  2. Trace water leaks

    What they doIf topping up is needed often, the technician inspects the heating system to find where water is lost before refilling.

    They must show youthe leak found.

    In writingthe repair carried out.

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.

  1. Gauge reading with the system cold

    No special tools

    Who:
    you.
    How:
    with the heating cold, read the pressure gauge at the bottom of the boiler or the display. Ferroli gives approx. 1 bar with the system cold and, on the BlueHelix models, says to restore it if it falls below 0.8 bar.
    Result that matters:
    the actual pressure.
    If it is low:
    move on to topping up.
    If it is correct and F37 remains:
    it points to the pressure switch or sensor; call the technician.
    Evidence to keep:
    photo of the gauge.

    Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento

  2. Top up with the filling cock

    No special tools

    Who:
    you.
    How:
    use the filling cock at the bottom to bring the pressure above 1.0 bar on the DIVAtop, or to about 1 bar on the BlueHelix models, while watching the gauge, and always close the cock at the end, as Ferroli says.
    Result that matters:
    the pressure reaches its value and F37 clears.
    If F37 clears:
    the boiler runs an air venting cycle (FH for 120 seconds on the DIVAtop, Fh for 300 seconds on the BlueHelix models).
    If you cannot raise the pressure:
    do not force the cock; call the technician.
    Evidence to keep:
    photo of the final pressure and the date.

    Do not open the casing. On the BlueHelix models the drain valve is inside the boiler and is not the filling cock.

    Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento

  3. If the pressure drops again

    No special tools

    Who:
    you.
    How:
    over the next days, check the cold pressure regularly, as Ferroli recommends.
    Result that matters:
    whether it holds.
    If it holds:
    it was a one-off loss or vented air.
    If it drops again:
    the water loss must be traced; call the technician and do not top up every day.
    Evidence to keep:
    note the date and pressure of each reading.

    Evidence: Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento

  4. Inspection by a qualified gas technician

    Tools required

    Who:
    a qualified gas technician, preferably from Ferroli's service network.
    How:
    checks the water pressure switch or sensor and its wiring and, if the pressure keeps dropping, looks for the leak in 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 HiTech RRT C 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

  • Alhena Tech C F37
  • Anomalía F37 Ferroli
  • caldera Lamborghini F37
  • Cointra F 37
  • Error F37 Cointra
  • Error F37 Ferroli
  • F-37
  • Ferroli error F37
  • Ferroli F37
  • Ferroli F37 boiler
  • Ferroli F37 caldera
  • Ferroli F37 presión
  • Ferroli F37 pressure
  • Lamborghini boiler F37
  • Lamborghini Caloreclima F37
  • Lamborghini F37
  • Lamborghini low water pressure
  • Lamborghini presión de agua baja
  • Superlative F37
  • turboMAG F.37
  • turboMAG plus F37
  • Vaillant F.37
  • Vaillant F37 calentador

What it means

Ferroli defines F37 as incorrect system water pressure on the DIVAtop MICRO LN F, BlueHelix HiTech RRT C and BLUEHELIX TECH RRT 28 C. Causes: pressure too low, or the water pressure switch or sensor disconnected or faulty. It is an F code: it clears on its own when the pressure returns to its value. After topping up, the boiler runs an air venting cycle (FH or Fh). If the pressure keeps dropping, the code does not say where the water is lost.

Warnings and stop conditions

  • Mediumeditorial warning

    Topping up the boiler every few days is not normal: it indicates a water leak that a technician should trace.

    Evidence: Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento

  • Mediumsource verified

    Always close the filling cock afterwards: Ferroli asks for it explicitly. If the pressure goes too high, the DIVAtop shows another fault (F40) for high pressure.

    Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento

Symptoms and causes

Probable causes · in order

  • System pressure too lowCommon

    The main cause in the table. It is confirmed by reading the gauge with the system cold.

    Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento

  • Water pressure switch or sensor disconnected or faultyPossible

    It fits if the gauge shows a correct pressure and F37 stays on the display.

    Evidence: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento

Virtual technician

Does F37 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.

Start diagnosis

Sources and technical references

  1. 1

    Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento

    Ferroli · 2015 · manual

  2. 2

    Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento

    Ferroli · 2021 · manual

  3. 3

    Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimiento

    Ferroli · 2018 · manual

Sources: Ferroli DIVAtop MICRO LN F instrucciones de uso instalación y mantenimiento · Ferroli BlueHelix HiTech RRT C instrucciones de uso instalación y mantenimiento · Ferroli BLUEHELIX TECH RRT 28 C instrucciones de uso instalación y mantenimientoreviewed 2026-10-03 · verified

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