L1Ideal
Ideal L1: no water flow or overheat, or a condensate pipe blockage, depending on the model
Checked against Ideal's own documentation: Ideal Logic Combi ESP1 installation and servicing instructions (UIN 222353) and 2 more sources. Last reviewed October 2026. How we check
Check these first, then call an engineer
Ideal uses L1 for different faults on different models. On the Logic Combi it's a flow temperature overheat lockout, which Ideal's general guide describes as flow temperature overheat or no water flow. On the Ideal Exclusive 2, L1 means a condensate pipe blockage. The checks below cover both.
What you can safely do
- Check the pressure gauge reads between 1 and 1.5 bar, and top up if it is low.
- Make sure your radiator valves are open.
- Check the condensate pipe outside for a blockage or ice, and thaw it with warm water or a hot water bottle if frozen.
- Reset the boiler.
Call a Gas Safe engineer if
- L1 comes back after these checks.
- You smell gas at any point. Leave the property and call 0800 111 999.
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.