Boiler Servicing and CP12’s Explained Re February 3, 2023

Boiler Servicing and CP12’s Explained

Engineer repairing a boiler

Many of us forget about our boiler until there becomes an issue with it, which is when we are then faced with a very expensive repair charge. To avoid this, your boiler should be serviced annually.

Boiler Servicing

Choosing the correct boiler for your home is an important investment and will keep you and your family warm for the next 10-15 years, hopefully. With this said, the lifespan of your boiler all depends on how well you look after your boiler.

As with all appliances, over time, your boiler’s efficiency will naturally decline slightly, however, ensuring that your boiler has an annual service will help to prevent your boiler from suddenly breaking down on you, as well as expensive repair costs. 

The majority of boiler manufacturers state that not having your boiler annually serviced can result in your boiler warranty becoming invalid. 

If you would like to know more information about boiler manufacturer servicing rules and the process they follow, we have mentioned this at the top of our boiler brand pages or you can click the sub-titles below:

What does an annual gas boiler safety check involve?

It is important that you get your gas appliances annually serviced. With your boiler being such a large gas appliance, it is essential that this is checked over regularly. Once a year you will need to arrange for a Gas Safe registered engineer to visit your property or commercial premises. They will carry out an inspection to ensure your gas fittings and appliances are safe to use.

With your permission your Gas Safe Engineer will:

  • Have the manufacturers’ instructions for your boiler available.
  • Operate the boiler briefly and ensure it appears to work correctly. Isolate the boiler/heating system electrically and confirm this with suitable test equipment. Check the fuse rating for the boiler/heating system is correct.
  • Remove the boiler case and carry out a visual inspection of the appliance, internally and externally, for any signs of distress (e.g. corrosion, water leaks etc.)
  • With due regard to the manufacturers’ instructions, clean the boiler and its components as necessary (e.g. primary heat-exchanger, burner, any condensate trap.)
  • Safely reinstate the electrical supply, before carrying out a check of the boiler’s gas burner pressure, a gas-rate check (taken at the gas meter), or both (as appropriate.)
  • The heating engineer should visually check the boiler’s flames (where visible) and carry out a flue-gas-analysis test.
  • Ensure that any combustion analysis test points are correctly replaced and that any boiler case seals are forming an effective seal.
  • Check that any ventilation requirements for the boiler have been met.
  • Check the boiler flue throughout its length, including its point of termination. Carry out flue-flow & spillage tests (smoke tests) if the boiler is of an open-flued type.
  • Check that any boiler safety devices operate correctly.
  • Important safety checks should be carried out, such as checking that there is no leakage of gas from the boiler, or its connecting pipework (for gas appliances.)
  • In the event of any safety defect(s) being noted; advise you of the details, and either rectify these or act in accordance with the Gas Industry Unsafe Situations Procedure (GIUSP.)
  • Where rectification is not possible, discuss with you any remedial action necessary, and the options to correct the fault(s).
  • Complete the Benchmark service report and record, and provide any additional work documentation, either routinely in line with business policy, or if you request this.

What is a CP12?

The name of CP12 certificates is an abbreviation of CORGI Proforma 12. From 1991-2009, the legally authorised regulatory body for UK gas installers was referred to as a CORGI (Council for Registered Gas Installers) and it was them who gave the CP12 certificate its official classification.

A Gas Safety Certificate is referred to as a CP12 amongst the trade industry. This certificate is a report which outlines the gas applications that have been tested during an annual gas safety check.

A Gas Safety Certificate, also known as a CP12, is a legal requirement in the UK for landlords and owners of commercial premises that use gas appliances. It is essential that all appliances are tested and serviced regularly to ensure that they are working efficiently and more importantly, safely.

Once you receive your Gas Safety Certificate, it is then valid for twelve months. It must be renewed annually. Tenants must be issued with a copy of the CP12 certificate within 28 days of the document being issued. Landlords are legally required to keep their copy of the form on file for a minimum of two years to allow for any auditing to be carried out should it be deemed necessary.

Any engineer carrying out gas safety inspections and issuing CP12 certificates must be registered with the organisation. Gas Safe has a search function on its website which allows anyone to check on the registration status of a particular engineer and search for registered professionals in their area.

What does a Gas Safety Certificate (CP12) say?

After a Gas Safe registered engineer has visited your property and completed your annual service they will document the following:

  • The date
  • The address of your property
  • A description and location of each appliance and flue checked
  • The faults and defects identified and any action required or taken to fix them
  • The results of operational safety checks carried out on the appliances
  • The name and registration number of the engineer who conducted your check

How much does a CP12 cost?

There is no set price for a CP12 certificate and it’s entirely up to the engineer how much they charge for the inspection and issue of the document. Prices can range from as little as £35 to as much as £150 or more, with no discernible difference in the service. And this is just for the certificate itself – the cost of any repairs which need to be made because of a failed inspection are additional.

Can I get a digital copy of a CP12?

CP12 certificates are usually completed on bulky pads of triplicate paper. With an engineer’s day involving dirty work, these important documents can quickly become greasy and battered, resulting in looking unprofessional.

With digital gas certificates, all forms will be legible and look professional. Copies can be instantly sent to everyone who is entitled to one, and they can be stored on a computer instead of in bulky filing cabinets. In addition, touchscreen signature capture features mean there is no need to ever print out a physical copy.

A digital and paper-free solution will also allow field service companies to improve their carbon footprint and work towards a more sustainable industry.

What will happen if I don't get my boiler serviced?

As mentioned, many manufactures will void your warranty if you fail to have your boiler serviced annually. However, failing to comply with this can cause more harm to yourself and others around you, than you think. 

So what are the consequences of not getting your boiler serviced? 

One major problem that can be caused by a result of maintaining your boiler is CO2 poisoning. Carbon Monoxide is a silent killer. Carbon Monoxide is an odourless, tasteless and colourless poisonous gas formed by the incomplete combustion of fuels. This gas is found in the fumes or fuels that contain carbon, such as wood, coal, and gasoline. 

Once Carbon Monoxide enters your system, it mixes with the haemoglobin (a molecule in red blood cells that carries oxygen around your body) in your bloodstream to form carboxyhaemoglobin. As a result of this, the blood is no longer able to carry oxygen, causing the body’s cells and tissue to fail and consequently, die.

If you want to learn more about Carbon Monoxide and its dangers, head over to our other blog.


Warning notices on gas appliances

During your annual Gas Safety check, your Gas Safe registered engineer will inspect your gas appliances to ensure that they are not unsafe to use. Your Gas Engineer will follow a process similar to the following:

They will fix any faults that are present during the boiler service.

They will advise you of any appliances that may need to be repaired before you continue to use them.

If your Gas Safe engineer can’t repair the appliance straight away, then, with the permission of the homeowner, they will then turn off the gas supply to this appliance to ensure the safety of those in the home. This is often referred to as Riddoring.

You may find that your Gas Safe engineer will attach a label to your appliance indicating that the device is dangerous and should not be used. You should also be given a notice stating either:

  • Immediately Dangerous (ID) – This means that the appliance can not be used and is considered a danger to life and property. This appliance should be disconnected from the gas supply immediately.
  • At Risk (AR) – This indicated that the appliance cannot be used, it is considered to be a danger to life and property. There are issues that without repair would endanger lives.

If you refuse to allow an engineer to make the appliance safe, he will report the situation to the Gas Emergency Service Provider (ESP) who have legal powers to enter a property and make the appliance safe.

What does RIDDOR stand for?

RIDDOR stands for the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 2013. These regulations came into force in October 2013. This is where your Gas Safe engineer can decide to remove the gas supply from a certain gas appliance.

Regulation 11 of the RIDDOR 2013 refers to gas-related injuries and hazards. 

The regulation states that a report should be made “where a conveyor of flammable gas through a fixed pipe distribution system, or a filler, importer or supplier of a refillable container containing liquified petroleum has, receives notification of the death, loss of consciousness or taking to hospital of a person, because of an injury arising in connection with that gas”,  that person must notify the Health and Safety Executive of the incident and send a report within 14 days. 

Regulations also state that it is a legal requirement that a report is made to the Health and Safety Executive within 14 days if there are signs of accidental leakage of gas, incomplete combustion of gas and inadequate removal of the product of combustion of gas. 

Reporting to the Health and Safety Executive

The Health and Safety Executive is an organisation that focuses on the safety of employees at the workplace. Their mission is to prevent work-related death, injury and ill health.

The Health and Safety Executive proudly support businesses – through free guidance and advice. By giving employers the confidence to manage risks correctly, we boost productivity, support the economy and contribute to a fairer society.

How to make a report to HSE
Visit and complete the online form. Once completed, your form will then be submitted to the RIDDOR database and you will receive a copy of the records.

Please keep reading for an extra minute. In 2010, a tragic incident happened to the family of Katie Haines. Katie lost her life to accidentally Carbon Monoxide poisoning. A memorial trust was founded in 2010, soon after Katie’s death, in order to raise awareness of the danger of CO and the result of not having an effective, working Carbon Monoxide alarm. Please don’t let yourself or a loved one be a victim of this deadly gas. Please visit the Katie Haines Trust to read more. 

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