What Happens During a Boiler Service?
If you have never had your boiler serviced before, or you are simply curious what an engineer actually does during the visit, this guide walks through the typical process step by step. Understanding what is involved can also help you appreciate why an annual service is worth keeping up with, even when your boiler seems to be working perfectly well.
All boiler servicing work referred to here must be carried out by a Gas Safe registered engineer, and none of the steps described are suitable for DIY attempts given the gas and combustion elements involved.
Initial Visual Inspection
The engineer will begin with a visual check of the boiler casing, surrounding pipework, and the general installation for any obvious signs of damage, corrosion, or previous poor workmanship. They will also check that the boiler has adequate ventilation and that nothing has been placed too close to it that could obstruct airflow.
Checking the Flue and Ventilation
The flue, which safely removes combustion gases from the property, is checked for correct termination position, secure joints, and any signs of blockage or damage. This is one of the most important safety checks carried out during a service, as a faulty flue can allow dangerous gases to enter the property.
Gas Pressure and Burner Checks
The engineer will check the incoming gas supply pressure and the burner pressure against the manufacturer's specification, adjusting where necessary and permitted. They will also inspect the burner itself for signs of uneven combustion or soot staining, which can indicate a problem with the fuel-air mixture.
Heat Exchanger and Internal Components
Depending on the boiler design, the engineer may inspect the heat exchanger for signs of scaling, corrosion, or blockage, and check other internal components such as the fan, ignition system, and seals for wear.
Safety Device Testing
Safety devices, including the flame supervision device and any pressure relief mechanisms, are tested to confirm they respond correctly. These devices are designed to shut the boiler down safely in the event of a fault, so confirming they function is a core part of any service.
Final Checks and Paperwork
Once checks are complete, the engineer will confirm the boiler is operating safely and efficiently, and will issue documentation confirming the service has taken place. If a Gas Safety Certificate has also been requested, this will be issued alongside or as part of the visit.
Cost of a Boiler Service
A boiler service or Gas Safety Certificate costs £99 + VAT during weekday hours, covering up to two appliances, with £40 + VAT for each additional appliance. If you would like both a service and a certificate carried out together, this is available as a combined package at £160 + VAT on weekdays.
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