F7Ideal
Ideal F7: low mains voltage
Checked against Ideal's own documentation: Ideal Heating: what does my boiler fault code mean?. Last reviewed October 2026. How we check
Engineer only
Ideal's general fault code guide describes F7 as: low mains voltage.
What you can safely do
There is nothing you can safely do yourself with this one. Leave the boiler off and book an engineer.
Before you book an engineer
- Write down the code exactly as the display shows it: F7.
- Find your boiler's model name. It is usually on the front panel or in the user manual. The table below shows why it matters: Ideal codes can mean different things on different models.
- Note when it started and what the boiler was doing (heating, hot water, or starting up).
- If the boiler is still under warranty, check your warranty paperwork before you book anyone.
Call a Gas Safe engineer if
- Ideal says the mains voltage is too low and to contact an electrician.
Find a Gas Safe engineer near you
Opens the official Gas Safe Register search.
Applies to Ideal boilers (Ideal's general fault code guide). Codes can differ between models, so check your manual.