BoilerFaultCodesIdeal H7 Fault Code
The Ideal H7 fault code means: your boiler has detected that the electricity supply from the mains is either too high or too low for it to operate safely.. It appears on 1 Ideal model in our database.
Technical description: Mains High Voltage or Low Voltage Error
What causes the Ideal H7 fault?
This fault occurs when the boiler's internal sensors detect that the incoming electrical power is outside the safe operating range of 230 volts. The most common reason is a fluctuation or surge in the local power grid, or a failing component on the control board misreading the incoming voltage.
This fault is more common during severe winter storms, as falling branches or high winds can cause power surges and fluctuations in the local electrical grid.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Ideal models that show the H7 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ideal H7 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