Intermittent boiler faults: how to catch a fault that hides

An intermittent boiler fault — the facts that change the job

• Photograph the display every time the fault appears
• Note outdoor temperature and wind — both are diagnostic
• Record whether heating, hot water or both were running
• Weather-correlated faults are usually condensate or flue
• Time-correlated faults are usually controls or scheduling

An intermittent boiler fault: the short technical version

We ask for a simple log: date, time, outdoor conditions, what was running, what the display showed and how long it lasted. Patterns emerge quickly — cold mornings suggest condensate, hot water only suggests gas rate, windy nights suggest flue, and once-a-week suggests a control schedule. That evidence turns a random callout into a targeted test.

Where we deal with this

• Larkhall (BA1) · 9 mi
• Widcombe (BA2) · 8 mi
• Wellow (BA2) · 3 mi

Questions we get asked

Why can't the engineer just find it?

A boiler that is running correctly gives no fault to measure. The log tells us what to provoke and what to test.

Do you charge for a second visit?

We are upfront about diagnostic time before we start, and a good log usually reduces it.