Baxi E110: overheat lockout on a Baxi combi or system boiler

A Baxi E110 overheat — the facts that change the job

• Flow and return temperature split is measured, not estimated
• A seized pump or shut valve stops heat leaving the exchanger
• Sludge build-up produces the same symptom gradually over years
• Sensor faults are possible but less common than flow restriction
• Repeated overheating shortens the heat exchanger's working life

Where a Baxi E110 overheat usually comes from

The usual root cause is heat unable to leave the exchanger fast enough — a seized pump, a closed valve elsewhere in the system, or sludge lining the pipework and choking flow. A genuinely faulty temperature sensor is a smaller but real possibility. An engineer measures the temperature split across flow and return before touching any part, because that single figure separates a circulation fault from a sensor fault reliably.

Where we deal with this

• Lansdown (BA1) · 9 mi
• Glastonbury (BA6) · 13 mi
• Bath (BA1) · 8 mi
• Wells (BA5) · 10 mi
• Bruton (BA10) · 13 mi

Questions we get asked

Is a flush always needed after E110?

Only where sludge is confirmed as the cause; some cases are a single valve or pump fault instead.

Can I reset E110 more than twice?

No — two attempts is the limit before it needs proper diagnosis.