A Complete Guide to Gas Boiler Services

In the same way your car needs a regular check-up at the garage, your boiler needs a regular service. It gives you peace of mind that everything’s working properly. And it could help to prevent your boiler breaking down. Since an engineer should pick up on any faults before they become a problem (and more expensive to fix) further down the line.

Keeping your boiler in tiptop condition also helps it work most efficiently. If your boiler is having to work hard to provide the same level of heat or hot water, then it’s not going to be working as effectively. Which means your energy bills are likely to be higher than they should be.

More than that, though, a boiler service could keep you safe. During a gas boiler service, an engineer will check there aren’t any leaky pipes. Since this could allow carbon monoxide to escape, which could make you ill or prove fatal.

It’s not a legal requirement to have a boiler serviced annually – unless you’re a landlord then you need to at least have a gas safety check (see landlord boiler service, below). But most warranties – if your boiler is still under warranty – will be invalid if you don’t maintain regular servicing.

And, just like your car, a boiler service needs to be carried out by a professional – in this case a qualified engineer. It’s not something you can do yourself at home, although there are things you can do to keep your boiler ticking over.

If you need a gas boiler service, Gas Safe are the accredited body to check your engineer is registered with. (Be aware that there’s no such thing as a Corgi boiler service anymore; Gas Safe replaced Corgi as the national gas registration body a decade ago.) Also use a Gas Safe engineer for an LPG boiler service or back boiler service. As both involve working with gas.

But if you require an oil boiler service or have a biomass boiler that needs servicing, make sure the engineer carrying out the work is OFTEC-registered.

Got an electric heating system instead? The good news is there’s no requirement to have an annual electric boiler service. Electric boilers also have fewer moving parts, so there’s less chance of things going wrong or deteriorating with age^[1].

If you’re worried your boiler isn’t working properly, you might want to consider a boiler repair instead. This way you can get the fault diagnosed and sorted straight away.

As part of a boiler service, an engineer will test everything’s working correctly. And these checks should flag up any problems. So if your boiler is due a service, you could wait for this. But bear in mind that any repairs on top of the usual checks (see below) aren’t typically included in the cost of a gas boiler service. And it might be a repair that requires the engineer to come back another time to fix. If in doubt, talk to the boiler service or repair company to find out.

Different providers offer different types of boiler service. But a good engineer will really get under the hood of your boiler to check how it’s working.

You’ll need to be at home, so that you can show them where the boiler is and the location of anything else they might want to inspect. Most services then follow a similar checklist approach^[2]. For instance, a visual examination of how the boiler has been installed, that it’s still functioning correctly, and any signs of damage or corrosion. The engineer will also check for water leaks. (If your boiler’s leaking water, read this blog to find out what could be causing it.)

Also, expect the engineer to check the controls, the electrics and if the boiler is vented correctly. They’ll remove the boiler casing to look inside the boiler – and check all the components are working as they should. And they’ll likely carry out some sort of maintenance. For instance, removing any dirt or debris around the fan assembly. Checking the connections on the heat exchanger. And making sure all combustion seals are intact – this is a really important safety measure.

An engineer will check the boiler is working correctly. For instance, that the pilot light is on and glowing blue (a yellow, orange red, purple or green flame indicates a problem). They’ll also check your boiler’s at the right gas pressure. Not sure what the correct boiler pressure is? Read this blog.

What’s a gas safety check?

During a gas safety check, an engineer checks all the gas appliances in your home – including your boiler – to make sure they’re operating safely. The clue’s in the name: the focus is on safety^[3]. During a boiler service, the engineer will check your boiler and related parts – like the flue – are operating safely. But they’ll also inspect the boiler parts for wear and tear too, and make sure everything’s functioning correctly.

And they’ll probably carry out various tests too. For instance, checking the performance of the flue. And taking carbon monoxide and carbon dioxide readings from the boiler.

What isn’t included in a gas boiler service?

Generally you have to pay extra for any repairs that need doing as part of the service – along with the new parts and labour cost to install them. You’ll pay extra for any new appliances too – such as a new carbon monoxide detector. And obviously should your boiler be dangerous or too faulty to fix, you’ll need to pay for a boiler replacement.

Also, be aware that some providers might charge a cancellation fee if you cancel at very short notice. If you’re unsure, ask the company arranging the service for a breakdown of exactly what is and isn’t included in the boiler service.

An oil boiler also requires an annual service to make sure it’s safe and working properly. The main difference with an oil-fired boiler service is that you want an OFTEC-registered engineer to come and check your boiler, instead of a Gas Safe engineer.

The oil engineer will carry out similar checks to those carried out during a gas boiler service – a visual examination of the parts, for instance. And he or she will work through a standard checklist from OFTEC. But an oil boiler service typically takes a bit longer than a gas boiler service. As the engineer may need to spend longer on cleaning and replacing some of the parts that deteriorate over time.

An oil boiler service can work out more expensive than a gas boiler service – especially if the engineer is spending more time at your property. Replacing parts tends to be more pricey too. So the oil boiler service cost could be as high as £120 – £180^[4].

You might be able to get it cheaper – we did also find an estimate for £70-£90^[5]. But again, it comes down to a number of other factors too – like your location, the time of year you’re getting a service (aim for the summer when engineers aren’t as busy), and the size and type of oil boiler that you have.

If you’re a landlord, there isn’t the same legal requirement to have a landlord safety certificate for an oil-fired boiler, as there is for a gas boiler^[6]. But it’s good practice to maintain your oil boiler and ensure it’s operating safely for your tenants.

There are plenty of Gas Safe engineers who can carry out an LPG boiler service and give you peace of mind that it’s working properly. As with any gas appliance, you’ll want to get the boiler serviced annually. And you can pay for a one-off boiler service or cover the cost with an annual service plan. Gas boilers are the most common type, so these services tend to come in cheaper. But an LPG boiler service will typically only work out £10-£30 more^[9].

What about back boiler services? Back boilers are an older type of boiler that you can no longer buy new. But there are still many in existence, particularly in 1960s and 1970s properties. Like other gas appliances, they need to be checked regularly. And a typical back boiler service will take two hours^[10].

Costs vary – but you can expect to pay around £100 or higher^[11]. Some providers also offer boiler service cover so you can spread the cost of the service over 12 months. But make sure any policy includes this boiler type. And that any engineer coming to service the boiler has experience with your brand (usually a Baxi).

It depends on what type of boiler you have and what checks your engineer carries out. How much you pay for a boiler service will also affect how long the engineer is at your property.

But expect a comprehensive service to take about an hour. Which? recommends that if it’s any shorter than 30 minutes, you should ask why.

When the engineer’s finished, they’ll usually put a sticker on your boiler letting you know when the next service is due. Ideally you want a service report – or a summary of what happened during the boiler service. This covers what the engineer found and shows that your boiler is up to a satisfactory standard.

There’s no formal document, like a boiler service certificate, to prove you’ve had a service. But if the engineer has carried out a gas safety check, you might receive a Gas Safety Record. It’s a legal requirement for landlords to have one of these – see Landlord boiler service, below – but not homeowners.

The cost of a boiler service depends on which provider you use and what type of boiler you have. According to Which?, the average cost for a gas boiler service is £72. This should get you a thorough inspection of your boiler, with the engineer running through all the checks above. Obviously if the engineer finds any faults, expect to pay more.

Many boiler cover packages give you a ‘free’ boiler service in the first year you take out a contract – see more on boiler service plans below. Remember though that this isn’t really ‘free’. Since you’ll be swapping a one-off annual boiler service price for a monthly boiler service plan cost (sometimes you can pay annually for a plan too).

If your boiler is under warranty, you’ll still have to pay for a boiler service. But you might get the cost of any replacement parts covered by the manufacturer. You’ll need to have registered your warranty when you had the boiler installed. And also meet any other qualifying criteria – such as servicing your boiler regularly. As always, check the small print!

Unfortunately not. But if your boiler service reveals that you need a new boiler, you might be able to get help with the cost of a boiler replacement. The Government’s ECO scheme helps cover the cost of energy efficiency improvements in the home – like buying a new energy-efficient boiler. And was set up to help those on low income or vulnerable households.

Learn more about the ECO scheme

There are all types of boiler service plans – and all types of providers. So definitely read the small print to check exactly what you’ll be getting cover for. Especially since costs can vary considerably too.

Read more in our How to Choose the Best Boiler Cover or Home Emergency Insurance blog.

You may be able to get a boiler service as part of your home insurance – but it’s unlikely. Usually this is only included if you pay for an add-on service or take out supplementary cover, like a home emergency insurance plan. Most insurers exclude boiler cover from their home insurance policies, as things can go wrong all too easily^[12].

According to Which?, the cost of a one-off boiler service is £72. But the cost can vary depending on where you live, the type of boiler service you pay for and which firm does the service. So the real cost of a one-off service might be anywhere between £70 and £135^[13].

Compare that to the cost of a boiler service plan, which can be anything from £8.50 for a basic boiler care plan to £24 a month including your heating, plumbing and electrics too^[14]. This works out at £102 a year for the cheapest cover. And £288 a year for the most extensive insurance policy.

Both types of boiler service plan work out more expensive. But you do get peace of mind that should anything go wrong, an engineer will be round to fix it – you’re not just paying for an annual boiler service. And with the average cost of a repair coming in at £270^[15], you may be better off with boiler cover.

If you decide you want the security that a boiler service plan gives you, there are three things you should definitely do:

• Shop around for the best deal;
• Read the small print on any policy;
• Check out customer testimonials for any providers.

Read more in our How to Choose the Best Boiler Cover or Home Emergency Insurance blog.

If you rent, rather than own your home, it’s your landlord’s responsibility to look after the boiler. So it’s their job – not yours – to make sure it’s working and fix it if there’s a breakdown.

Like homeowners, landlords can pay a fixed fee for a one-off boiler service. And as part of this,  they'll get a CP12 Gas Boiler Safety Certificate – also known as a Gas Safety Record. This is important because it proves they've met the legal requirement to have a gas safety check carried out at your rental property.

Alternatively, they can pay a monthly or annual fee for a service plan. Although these are targeted at landlords and come with similar features to homeowners’ policies. But its best to make sure they always include the annual CP12 Gas Safety Certificate and Inspection.