High
Low system pressure neon lit on Ideal Classic FF

Your boiler has detected that there is not enough water in the central heating system to operate safely, so it has shut down to protect itself.

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

The low system pressure neon is illuminated, indicating the system pressure is too low.

From this model's manual
Verified against the Response Ff80 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.

What causes this fault?

This fault occurs when the water levels inside your radiators and pipework drop below a functional level, meaning the boiler can no longer circulate heat safely. The most common reason is a tiny leak somewhere in the system or because the air was recently bled out of your radiators without topping the water back up. In some cases, a failing internal component like the expansion vessel may be causing the pressure to fluctuate and escape.

This issue often surfaces when you turn your heating back on for the first time in autumn, as the system settles after being dormant all summer.

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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