New boiler noise after a service: what to report
Report a new or noticeably different boiler noise after a service promptly, with the timing and operating conditions. The sequence is useful evidence, but does not by itself prove what caused the sound. A follow-up should compare the reported change with the service findings and investigate the appliance or system as needed.
Loyal Plumbers · Updated
Discuss your plumbing workStart with any immediate safety signs
A loud or alarming new sound, repeated lockouts, visible leakage or an overheating indication needs prompt assessment. Stop using the appliance through its normal controls if safe to do so and seek advice. Do not repeatedly run it to capture the perfect recording or remove the casing to locate the noise more closely.
If you smell gas, suspect a gas escape, hear a carbon monoxide alarm or suspect carbon monoxide exposure, leave the building and call 0800 111 999 from outside. Seek medical help for possible exposure and call 999 for severe symptoms. Those signs take priority over contacting the servicing company or establishing whether the noise began during its visit.
Build a short before-and-after timeline
Write down when the service took place and when the new sound was first noticed. Distinguish a sound that began immediately when the boiler restarted from one noticed several days later. Include whether heating had been unused for a while and whether the service was the first occasion the whole system ran that season.
List any other work or changes around the same time: radiator adjustments, building work, a changed thermostat programme or water-supply interruption. This does not dismiss the connection with the service. It gives the engineer enough context to investigate fairly and avoids overlooking a separate event that affected the system between the appointment and the report.
Describe the sound without turning it into a diagnosis
Words such as hum, rattle, whistle, gurgle, knock or bang can help communicate the complaint. They do not identify a component reliably on their own. Sound can travel through pipes and furniture, making a noise seem to come from the boiler when its source is elsewhere. Describe where you hear it and whether that location changes.
If it is safe to observe from outside the equipment, note whether the sound begins before heating starts, while it runs or after it stops. A short recording can help convey the pattern if the team requests one by email. Do not hold a phone inside an enclosure, touch hot components or obstruct ventilation to make a clearer recording.
Explain which demand brings it on
A combi boiler can behave differently during heating and a hot-water draw. A system with a cylinder can have separate heating and cylinder-reheat demands. Tell the engineer whether the noise occurs with radiators warming, a tap running or a timed hot-water period. Do not assume every noise associated with hot water originates inside the boiler.
Also say whether the noise occurs throughout the cycle or only when a control changes state. If you already noticed a connection with one radiator valve or a particular room, report it without repeatedly adjusting the system. The aim is a useful description of normal-use observations, not a home experiment that introduces more changes before the engineer attends.
Read the service findings before the follow-up
Check whether the report already identified a noisy component, circulation issue or further work. If so, refer to the exact finding when contacting the team. A recommended repair that remains outstanding needs to be distinguished from a new symptom following completed maintenance. Keep the original report available rather than summarising it from memory.
Ask what work was completed and whether any settings were changed as part of the service. The engineer can review those details against the present complaint. Do not restore remembered settings inside the appliance yourself. Some changes are technical adjustments requiring checks, and an unexplained return to the old position can obscure the problem or create a safety issue.
Agree what the return visit will investigate
The follow-up should address the reported change and any related safety or operating concern. Depending on the evidence, the engineer may need to assess the appliance, controls, circulation or connected pipework. A sound description alone is not a reason to order a pump, clean the system or replace the boiler before diagnosis.
Clarify the scope and any charging or authorisation arrangements directly with the company. Do not assume that a return visit is automatically chargeable, automatically free or an admission of fault. The practical priority is a safe assessment, a clear finding and agreement on the necessary work. Keep discussions about responsibility factual and supported by the documented sequence.
Record the outcome rather than only the disappearance
After any adjustment or repair, ask what was found and how the relevant operating conditions were checked. If the noise is intermittent and cannot be reproduced, agree what further observations are useful and when to report it again. A quiet moment during a short visit is different from establishing that the cause has been resolved.
Loyal can investigate boiler and heating noises across London inside the M25. Include the service date, the noise pattern, any code and the effect on heating or hot water in your enquiry. If our team performed the service, refer to that booking so the findings can be reviewed together. Leave technical adjustments and internal inspection to the appropriately qualified engineer.
Common questions
- Does a new noise prove the service damaged the boiler?
- No. The timing is important evidence, but the cause needs assessment. Report the change promptly and keep the service findings and timeline available.
- Should I keep running the boiler to record the noise?
- Do not repeatedly operate a potentially faulty appliance. Safety signs take priority; use observations already made and follow advice about further use.
- Can bleeding radiators fix a new boiler noise?
- A sound alone does not establish trapped air as the cause. Avoid changing several things before assessment, particularly where the noise is new, severe or accompanied by a fault.
Sources and further reading
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