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  • Gastech Heating And Plumbing

What Does a Boiler Service Involve?

Updated: Feb 2, 2023

During a boiler service, an engineer will run a series of checks and inspections on your cental heating system, to ensure it is running at optimum levels to keep your efficiency high and energy bills low. Through intense scrutiny and inspection, they will even identify potential risks or leaks that could have potentially fatal consequences.

What’s A Boiler Service?

An annual check and test that’s carried out to ensure your boiler is working efficiently, a boiler service is pivotal in maintaining the health of your boiler. In fact, it’s now a binding requirement, and should you not service your boiler annually, you will lose your warranty. You cannot overlook the importance of getting your boiler serviced annually as it can lead to various problems, including a loss of hot water and heating. One of the major concerns is the increased threat of carbon monoxide poisoning, which can be potentially lethal for you or for your family, which is why it’s so important you book an annual service to ensure you avoid these issues.

When Should I Service My Boiler?

A boiler service is performed at least once a year. Your boiler must be serviced annually even if there is no issue or fault, to ensure your warranty remains valid. Remember, you won’t want your central heating system to go down in the winter, so we recommend that you have your boiler inspected and serviced during the summer to avoid any nasty surprises when the colder months close in.

However, if you are concerned your boiler is not functioning correctly, even if you have recently had a service, it’s advised you contact a qualified engineer to perform another inspection to check for any potential safety issues.

What’s Included?

There are several checks and tests that must be performed during a boiler service:

Visual Inspection

Your engineer will run a series of visual checks to ensure your boiler still meets current standards and regulations. They will also inspect the boiler for any signs of corrosion or leaks and check the flame is working inside the boiler.

Removal Of The Boiler Casing

Once the visual inspection is complete, the engineer will then check the components of the boiler to make sure everything is operating correctly. These checks will ordinarily include inspecting the heat exchanger, burner, main injector and spark probe. Once this is complete, they will then clean the boiler from the inside.

Flue Check

The engineer will then ensure there are no obstructions in the flue terminals and that the flue is safely fitted. This helps them check if there are any dangerous emissions being discharged.

Gas Pressure Check

A boiler operates with the assistance of the gas pressure, meaning it’s essential your gas pressures remain at the highest levels consistently. A gas pressure check will ensure your boiler is working at the correct pressure.

Boiler Fired Up

This is a simple on and off test that allows the engineer to check for any working faults within the boiler itself.

Why Have One?

Here are just some of the reasons why you should get your boiler serviced each year:


A great advantage of having your boiler serviced is that it allows the engineer an opportunity to identify any hazards or safety issues that may be affecting your heating system. As mentioned, this could potentially be a carbon monoxide leak. Carbon monoxide is a lethal odourless gas, and without regular inspection and service, there would be very little way of knowing if the gas was leaking from your boiler. If you’re ever concerned that your boiler is not functioning correctly, you should have it serviced as soon as possible, even if your annual service is not yet due. This will identify any weak spots, such as gas leaks or corrosion damage.


Over time, your boiler will gradually become less efficient, meaning it will need to burn more fuel to heat your home at previous levels which will end up costing you more in the long run. With an annual service, checks are performed to ensure all working components are in the best possible position to function correctly and deliver a higher level of efficiency for much longer.


As your boiler ages, losing efficiency, it will require servicing to maintain its regular standards. Annually servicing your boiler helps your energy bills down, and allows engineers to spot potential faults that will prevent your boiler from potentially breaking down and costing you a fortune in repair bills.


As an estimate, your boiler will usually include a manufacturer's warranty of up to fifteen years, which means any faults that develop in that time will be repaired free of charge. However, this warranty is only valid if your boiler is serviced by an engineer every year.

Warning Signs

Here are some of the key signs your boiler needs servicing:

Inactive Pilot Light

Your pilot light is the ignition for the boiler and should be switched on at all times. If your pilot light keeps turning itself off, it’s a sign that your boiler is not working properly.

Loud Noises

A functioning boiler will naturally let out a gentle hum as it turns on, but this will eventually fade into the background. However, if your boiler is making loud or unusual noises that don’t disappear, your boiler is no longer working correctly. On occasion your boiler may make strange noises caused by the natural wear and tear of the fan and pump. In any case, you should contact an engineer for servicing as soon as possible.

Unusual Odour

If you start to smell an unusual odour, it’s probably a sign that your boiler is leaking gas. Watch out for dark marks on the casing of the boiler, this is a clear visual sign that there is a leak in the system. You must contact your engineer immediately if you are concerned about your boiler leaking gas.

Inefficient Performance

If your heating’s been on all day and you still feel a chill in the air, it could be a sign of a boiler issue. You may want to try flushing your radiator system first, but in some cases, your radiators may be working even when the boiler is performing inefficiently.


The cost of a full boiler service isn’t set in stone, due to the subtle differences between boiler types and the location of your home, but on average, a standard efficiency boiler service will cost between £50 and £80, with a high-efficiency boiler service costing roughly double this figure. Unfortunately, if you do live in London, you are far more likely to be charged more than those living in rural areas.

It’s definitely worth considering having your boiler serviced during the summer, not just for efficiency purposes or to avoid problems in the winter, but because it will also help keep the cost down. In the summer months, boiler service companies will be far less busy, meaning they’ll be able to service your boiler without too much hassle and you won’t have to cough up for a broken central heating system in the future when you desperately need one that works.


On average, a boiler service lasts around thirty minutes. However, it’s worth keeping in mind this is a rough estimate that can vary depending on the type of boiler you own, and its make and model. After the service is complete, the engineer will provide you with a service report explaining what they’ve done, offering the appropriate advice if needed.

Gastech - Heating and Pluming Solutions Since 1986

At Gastech, we pride ourselves on being one of the most reliable heating and plumbing companies in South Wales. Established in 1986, we have decades of experience and expertise behind us. Not only are our certified Worcester Bosch boilers an affordable price, reliable and efficient, but they also ensure that your home is kept nice and warm without costing sky-high fees. As a matter of fact, the Worcester Bosch Greenstar condensing boilers are A-rated, guaranteeing 94% efficiency. Contact us for more information today!

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