A boiler service – more than just a five minute clean

Just like regular car servicing, an annual boiler service is important to make sure your gas boiler is running smoothly and efficiently. But how exactly do you service a boiler? Although all boiler makes such as Baxi or Worcester are slightly different, here we explain the basic steps that Gas-Safe engineers go through when servicing a boiler.

There are many different components of a combi boiler. To the right are the basic components we see when the front cover is removed.Components of a Baxi cambi boiler

Six steps to servicing a boiler

  1. When it comes to servicing your boiler, the first and by far the most obvious step is to remove boiler cover to get access and for an initial visual inspection. The seals around the edges are thoroughly checked to ensure that air is being introduced correctly into the boiler from the outside inlet rather than from the room where the boiler is housed.

A gas combustion analyser tests your boiler emissions2. Next, we use a Gas and Combustion Analyser machine to test the burner to see if it needs cleaning. Cleaning a burner is not something that needs to be done automatically since you need to break the seals to access the burner. However, if the readings suggest an issue then the next step would be to clean the burner component.

Both maximum and minimum gas flow rates are checked against the manufacturer’s specifications – the maximum rate of 8.7% CO2 for this Baxi boiler pictured was well within the required tolerances.

3. Next, we check the minimum gas pressure with a Gas Combustion Analyser (pictured left) – this one is OK at 23 MB (vs a recommended minimum of 16 MB). Gas flow into a boiler is affected by the size of pipe used and any modifications such as elbows also reduce gas flow. Modern boilers need more gas flow than older boilers and therefore it’s vital that the minimum flow is sustained.


Remove the boiler cover4. This Baxi combi boiler is known as “room sealed” which means that it takes the air from the outside. Therefore we need to check the seals to ensure that air is not being drawn in from the room. For these type of boilers, it’s important that the installer hasn’t cut out any panels to make extra room in a cupboard for example.

5. Next, we empty & inspect the condensation trap. This can stop a boiler working if it’s silted up and if it becomes cracked, it’s possible for fumes to escape.

Adding an inhibitor to a central heating system prevents the build up of sludge6. Finally, an inhibitor is added to the top inlet of the highest radiator in the house to clear the pipes and prevent any blockages.

If required, we may recommend installing a Magna Clean to remove sludge. This clever piece of equipment uses a magnet to filter out sludge from your system and this can be easily cleaned by either ourselves or the householder.

We promise to leave your premises in a clean and tidy state and will remove any excess materials as required. We’ll print out a report for your records or service book and we’ll be in touch in 11 months’ time to give you a gentle reminder about the next annual boiler service.

If you’re in the middle of searching on Google for “a boiler service near me”, save yourself some time and get in touch or call 07966 683 688   – we’ll be pleased to help. Peter Jones Plumbing Preston have been established for over 15 years and are Gas Safe registered. We service boilers for all types of domestic property in the Preston, Penwortham, Chorley and surrounding areas.