High
F7 on Keston System S30

Your boiler has stopped working because the electrical supply from the grid or your home's wiring has dropped below the level required for the unit to run safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

LOW MAINS VOLTAGE - CONTACT ELECTRICITY PROVIDER

From this model's manual
Verified against the Keston System S30 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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