Error code
Ideal Boiler Fault Code F9
The boiler is not seeing healthy water circulation The most likely cause is pump not moving water effectively. Check first: confirm radiator valves and room controls have not simply been turned off.
Quick answer
F9: what does it mean and how to fix
What does it mean?
The boiler is not seeing healthy water circulation
How to fix first
Check the boiler display and pressure gauge only as described in the Ideal user manual.
Why is this happening?
Pump not moving water effectively
When should I call an engineer?
Book a qualified heating engineer if F9 returns after one reset, radiators stay cold despite demand, the pump is noisy, or pressure and controls appear normal.
What does this error code mean?
Ideal boiler fault code F9 usually points to a circulation problem, where heated water is not moving through the boiler or heating system as expected. This is different from a simple low-pressure warning: pressure can be part of the picture, but pump operation, airlocks, restrictions, or sensor readings may also be involved.
This code usually points to the heating water circulation path, including the pump, trapped air, restrictions, or circulation-related sensors.
Start with this safe check: Check the boiler display and pressure gauge only as described in the Ideal user manual. If the code returns, the fault worsens, or the appliance does not behave normally, book a qualified heating engineer if F9 returns after one reset, radiators stay cold despite demand, the pump is noisy, or pressure and controls appear normal.
Symptoms users may notice
- The boiler may lock out instead of heating radiators or hot water.
- Radiators may stay cool even when there is demand for heat.
What users often notice
- The fault may return after a reset if the pump, air, or restriction issue is still preventing normal flow.
Why is this happening?
- Pump not moving water effectively
- Air trapped in the heating circuit
- Blocked or restricted circulation through the boiler or system
- Flow or temperature sensor readings suggesting poor movement of water
What this usually points to
This code usually points to the heating water circulation path, including the pump, trapped air, restrictions, or circulation-related sensors.
How to fix this safely
- Check the boiler display and pressure gauge only as described in the Ideal user manual.
- Confirm radiator valves and room controls have not simply been turned off.
- Use a standard user reset once only if the manual allows it.
- Do not dismantle the pump, valves, pipework, or boiler casing.
What not to do
- Do not remove the boiler casing or attempt to work on the pump, valves, or sealed components.
Common misdiagnoses
- Users may assume this is only a pressure issue, but F9 often needs circulation and pump-related checks by an engineer.
Reset steps
- Try one user reset after any permitted external checks are complete.
- Allow the boiler to attempt normal operation and watch whether F9 returns.
- Arrange an engineer if the circulation fault returns or the boiler heats briefly then locks out again.
Intermittent vs persistent faults
If F9 returns after a permitted reset, treat it as persistent and arrange qualified diagnosis rather than repeatedly resetting the boiler.
When to call an engineer
Book a qualified heating engineer if F9 returns after one reset, radiators stay cold despite demand, the pump is noisy, or pressure and controls appear normal.
Safety warning
Do not open the casing or interfere with pumps, valves, pipework, or sealed boiler components. Use only the user checks in the manual.
Useful hub links
Related circulation fault codes
Relevant guide
Frequently asked questions
Can I keep resetting an Ideal boiler with F9?+
No. Try one permitted user reset only. If F9 comes back, repeated resets will not fix a circulation fault and can delay a proper repair.
Is Ideal F9 the same as low boiler pressure?+
Not exactly. Low pressure can affect circulation, but F9 is more specifically about water not moving through the boiler or system correctly.
Can bleeding radiators clear F9?+
Air in the system can contribute, but bleeding radiators changes system pressure and should only be done if you are confident following the boiler manual.
Should I open the boiler to check the pump?+
No. Pump and internal circulation checks require a qualified heating engineer.