BoilerFaultCodesIdeal No Water Flow Fault Code
Also written as NOWATERFLOW — same fault.
The Ideal No Water Flow fault code means: your boiler has stopped working because the water pressure is too low or water isn't moving through the system correctly.. It appears on 5 Ideal models in our database.
Technical description: 1 With boiler off & system cold, fill system to 1.0bar. 2 Bleed radiators, refill system to 1.0bar. 3 If fault persists, contact installer.
What causes the Ideal No Water Flow fault?
This fault occurs when the boiler's internal sensors detect that water is not moving through the unit, which is a safety mechanism to prevent the components from overheating. The most common reason is a simple drop in system pressure caused by a small leak or air trapped in the radiators, though it can also be triggered by a blockage or a failing pump. Essentially, the boiler has detected it is 'running dry' and has shut down to protect itself from damage.
This issue often appears in autumn when the heating is turned on for the first time after summer, as air bubbles can settle or small leaks can develop while the system is dormant.
DIY fix possible
Check the pressure gauge and use the filling loop to top up the system to 1.0 barBleed all radiators to remove trapped airEnsure all radiator valves and boiler isolation valves are fully open
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Gas Safe Register →Ideal models that show the No Water Flow fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal No Water Flow fault code information on this page is sourced and cross-checked against the official Ideal service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026