BoilerFaultCodesIdeal H1 Fault Code
The Ideal H1 fault code means: your boiler has detected low water pressure in the system, which is preventing it from heating up.. It appears on 2 Ideal models in our database.
Technical description: ALTERNATING 'H' '1' GO TO FRAME 90
What causes the Ideal H1 fault?
This fault occurs when the water pressure inside your heating system drops below a safe level, causing the boiler to shut down to prevent damage. The most common reasons for this are a leak somewhere in your radiators or pipework, or simply that air has been bled from the system without being topped back up. It can also happen if a component like the expansion vessel has failed, causing water to be discharged through the safety pipe.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time or bleed their radiators to prepare for winter.
DIY fix possible
Locate the filling loop (usually a silver flexible hose) underneath your boiler.Slowly open the valve(s) until you hear water flowing and watch the pressure gauge.Close the valves once the needle reaches 1.5 bar on the gauge.
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A cover plan would handle faults like H1: no call-out fees, no surprise bills.
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Ideal models that show the H1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal H1 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 31 August 2026