F37 Ferroli Boiler Fault Code

The Ferroli F37 fault code means the primary system water pressure is too low or the water pressure switch is faulty. This fault may also appear as an A37 error code on Ferroli boilers.

Symptoms of the F37 error include cold radiators, low boiler pressure, little to no hot water, and reduced water flow.

To fix the F37 fault on a Ferroli Boiler, the central heating system will need to be repressurised.

To restore boiler pressure, you must top up the system via the filling loop.

If F37 codes persist, your boiler or central heating may have a system leak or a pressure valve issue.

ADI Leak Detection specialise in finding and repairing hidden water leaks on central heating systems – resolving the F37/A37 error code.

This is your troubleshooting guide.

Ferroli F37 Error code

Symptoms Of The F37 Boiler Fault Code

Symptoms of the F37 error code include:

  • Little to no hot water
  • Cold radiators
  • The boiler is suffering from loss of pressure
  • The boiler is not working properly
  • Ignition electrode fault
  • Low-pressure warning message (i.e. error code F37/A37)
  • Pressure gauge reading below 1 bar

How To Fix The Ferroli A37 (F37) Boiler Fault

You can clear the A37/F37 fault on your boiler by pressurising the central heating system.

Follow this step-by-step guide:

Step 1

  • Check the water pressure on the pressure gauge.
  • The optimum boiler pressure should be between 1 and 1.5 bars.

Step 2

  • If the pressure is too low (below 1 bar), repressurise the system via the filling loop. The filling loop is found underneath the boiler or near a sink, close to the discharge pipe. Refer to the boiler manual for its precise location.
  • Top up the pressure until it reaches the ideal system water pressure.

Step 3

  • Check for signs of a water leak along radiators, pipework, and valves.
  • Replace/repair any damaged components if needed.

Step 4

  • Reset the boiler by turning it off for a few minutes, then turn the boiler back on.
  • This will clear Ferroli boiler error codes if it’s a temporary issue.

Other tips

  • If repressurising and resetting the boiler doesn’t work, you might have a faulty pressure valve. Contact professional Gas Safe engineers to attend to the problem.
  • If you suspect a system leak – or the system loses pressure quickly – contact leak detection specialists.

What Should I Do If The F37 Error Code Keeps Displaying?

If the F37 fault code comes back after repressurising the boiler, you should contact a leak detection expert.
Professional heating technicians use non-destructive methods to locate water leaks in boilers and central heating systems. The non-invasive equipment includes tracer gas, acoustic listening devices, damp meters and thermal imaging cameras.

When the Ferroli boiler F37 error persists, attempt these DIY steps:

  • Safety first: Ensure your boiler is turned off and cooled down before attempting any DIY inspections.
  • Recheck leaks: Thoroughly inspect all radiators, pipework, valves, and the boiler unit for any signs of dripping water or excess moisture. Check the joints and connections for signs of dampness.
  • Pressure stability: Ensure the system water pressure is within the optimum range – between 1 and 1.5 bars. Take the pressure reading on the pressure gauge, located as a dial on older models or electric display screens on newer models. Refer to the boiler manual for its precise location.


If the F37/A37 Ferroli boiler fault code persists, especially when the above DIY steps have proven unsuccessful, contact plumbing professionals. ADI Leak Detection locate hidden leaks on your property, offering a cost-effective solution.

Adrian Morgan

Adrian Morgan CIPHE RP RHP is the founder & Managing Director of ADI Pro Leak Ltd. Adrian is also the Head Plumbing, Heating & Leak Detection engineer at ADI Leak Detection.

Adrian CIPHE RP RHP is proud to be registered with the Chartered Institute of Plumbing & Heating Engineering, a Registered Plumber and a Registered Heating Professional.