F1Ideal
Ideal F1: low water pressure
Checked against Ideal's own documentation: Ideal Heating: what does my boiler fault code mean? and 4 more sources. Last reviewed October 2026. How we check
You can usually fix this
The water pressure in your heating system has dropped too low for the boiler to run. Every Ideal guide we checked gives F1 this meaning, and the usual fix is to top the pressure back up.
Recommended pressure when cold for Ideal boilers: 1.0 to 1.5 bar.
What you can safely do
- Let the boiler cool down, then read the pressure gauge.
- If it is below 1 bar, top up using the filling loop until it reads between 1 and 1.5 bar. Your user guide shows how.
- Close the filling loop fully and check the gauge again.
Call a Gas Safe engineer if
- The pressure keeps dropping and you have to top up often.
- You can see water leaking from the boiler or pipework.
Find a Gas Safe engineer near you
Opens the official Gas Safe Register search.
Applies to Logic Combi (ESP1), Exclusive 2. Codes can differ between models, so check your manual.