High
F34 on Ferroli i25

Your boiler is failing to start because it is not receiving enough consistent electrical power from your home's mains supply.

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

Supply voltage under 140VAC

From this model's manual
Verified against the Ferroli/Ferroli I25 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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Related fault codes

F35View →F37View →

All 18 fault codes on the i25

Seeing a different code? Every code this model can display, in one place.

A01A02A03A06A09A15A16A23A24F07F10F11F35F37F43F50F51

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