Low
105 on Atag S 25CR

Your boiler is automatically running a short seven-minute cycle to remove trapped air from the system after it detected low water pressure.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

De-aeration program will start (approx 7 mins) after refilling if pressure was below 0.7 bar.

From this model's manual
Verified against the Atag S 25cr installation & service manual, page 53.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Wait for the seven-minute de-aeration cycle to complete automaticallyEnsure your system pressure remains between 1.0 and 1.5 bar on the gaugeMonitor the boiler for a few minutes to see if normal operation resumes once the cycle finishes

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