Table of Contents
- Recognising Unsafe or Illegal Gas Work
- What to Do First If You Smell Gas
- How to Report Illegal Gas Work to the Gas Safe Register
- Understanding the Gas Safe Register Complaints Process
- Gathering Evidence and Writing a Complaint Letter
- Booking a Verified Gas Engineer for Your Next Job
- Frequently Asked Questions
Recognising Unsafe or Illegal Gas Work
Last Updated: 9 November 2026
Gas work that puts your home at risk is not always easy to spot. Some signs are obvious, like a yellow or sooty flame on a gas hob or boiler.
Illegal gas work means gas work carried out by someone who is not registered with the Gas Safe Register. Unsafe gas work means an installation or repair that puts people at risk, whether or not the person doing it is registered.
Watch for these warning signs:
- A boiler or cooker flame that burns yellow or orange instead of blue
- Scorch marks or soot around a fire, flue or appliance
- Condensation or staining on walls near a flue or gas appliance
- Headaches, dizziness or nausea that ease when you leave the house
- A carbon monoxide alarm that sounds or a detector showing a warning
- An engineer who will not show a Gas Safe ID card or give a record of the work
Watch out: never ignore a carbon monoxide alarm, even if you cannot see or smell anything. Leave the property and call the National Gas Emergency Service on 0800 111 999 straight away.
What to Do First If You Smell Gas
If you smell gas, your first job is safety, not reporting. Open windows and doors, avoid switches and naked flames, and leave the property. Do not use your phone inside the building.
Once you are outside and safe, call the National Gas Emergency Service on 0800 111 999. If a check has already found a fault, see what to do if a gas safety check fails for the next steps.
Report the engineer through the Gas Safe Register once the immediate danger has passed. Keep the details of the work, the date and any photos for later.
How to Report Illegal Gas Work to the Gas Safe Register
The Gas Safe Register is the official body for gas safety in the UK.
To report a concern, follow these steps:
- Gather the engineer’s name, the address of the work and the date it took place.
- Check whether the engineer is on the register using their Gas Safe ID card number.
- Contact the Gas Safe Register through its concerns and reporting pages on Gas Safe Register reporting illegal gas work page.
- Say clearly what you saw, what the risk is and whether anyone is currently in danger.
- Keep a copy of your report and any reference number you are given.
The online concern survey typically takes 2 to 3 minutes to complete, according to Gas Safe Register concern reporting guidance.
Booking a verified engineer after a report: if the work needs fixing, it helps to know how to confirm registration before anyone else touches the appliance. Read our guide on how to check Gas Safe registration for engineers before you book.
Understanding the Gas Safe Register Complaints Process
The complaints process is a safety investigation, not a consumer dispute service. It examines whether the work breaches gas safety rules and whether the engineer’s registration is in order. It will not adjudicate a refund, a missed deadline or a poor finish, those are separate matters you pursue through the engineer, a complaints scheme or the small claims track.
Investigators triage on risk, so leading with the danger rather than the chronology is sensible.
The stages a report typically goes through
- Acknowledgement. The Register logs your concern and gives you a reference. Keep it, you will need it for any follow-up.
- Triage. The details are reviewed against the engineer’s registration record and the nature of the risk. Reports alleging immediate danger are prioritised over historical workmanship concerns.
- Information gathering. You may be asked for photos, invoices, the Gas Safe ID number shown, or a written statement. Respond promptly; stalled reports often stall because the reporter goes quiet.
- Engineer contact and inspection. The Register may contact the engineer, request records of the work, or arrange a site visit by an inspector.
- Outcome. The case may be closed with no further action (the work was compliant), resolved through advice or a requirement to rectify, or escalated where the law appears to have been broken.
What ‘escalated’ means in practice
Where the evidence suggests unregistered work carried out for payment, or work that breaches gas safety regulations, the Register can refer the matter on for enforcement. In serious cases this can lead to prosecution. The Register is not the prosecutor itself; it is the body that gathers and passes on the evidence.
Watch out: do not assume that filing a report automatically triggers a site visit or a prosecution. Many reports close at triage because the work turns out to be compliant or the concern is a commercial dispute rather than a safety breach.
Civil versus criminal routes, and when to take legal advice
These are two different tracks and mixing them up wastes time:
- Criminal route. Applies where the law has been broken, most commonly an unregistered person carrying out gas work for reward, or work that contravenes gas safety regulations. This is the Register’s territory. Report the safety concern first; enforcement follows if the evidence supports it.
- Civil route. Applies to your personal loss, a refund, the cost of putting bad work right, a broken contract. This is handled through the engineer’s own complaints procedure, a relevant alternative dispute resolution scheme, or the small claims track. The Register will not award you money.
If you are unsure which applies, report the safety concern to the Register first. That costs nothing and preserves the safety route. Take independent legal advice on any money claim separately, and keep the two sets of correspondence apart so neither undermines the other.
How long it takes and what to expect
Timelines vary with complexity and inspector availability. You are not usually kept informed at every stage, so if you have not heard anything after a reasonable period, follow up quoting your reference. Silence is not the same as inaction.
If you are worried about retaliation
If you have a genuine fear of reprisal, say so when you report so it can be factored into how the case is handled.
The Gas Safe Register handles safety concerns through a series of stages, summarised below.
| Stage | What happens | What you should do |
|---|---|---|
| Acknowledgement | The Register logs your concern and gives you a reference | Keep the reference for follow-up |
| Triage | Details are reviewed against the engineer’s registration record | Expect immediate danger reports to be prioritised |
| Information gathering | You may be asked for photos, invoices or a statement | Respond promptly to avoid stalling |
| Engineer contact and inspection | The engineer may be contacted or an inspector may visit | Let the Register handle contact with the engineer |
| Outcome | Case closed, resolved through advice, or escalated | Follow up quoting your reference if you hear nothing |
Gathering Evidence and Writing a Complaint Letter
Reports are easier to act on when the reporter gathers the right evidence before making contact and stays safe while doing so. This section covers both, because evidence collection is where well-meaning reporters most often put themselves at risk or undermine their own case.
Stop, isolate, ventilate, before you collect anything
If you suspect an immediate leak or carbon monoxide, do not start photographing. Run this checklist first:
- Stop using the appliance. Turn the gas off at the meter if you can reach it safely.
- Isolate the area, keep everyone, especially children and pets, out of the room.
- Ventilate by opening windows and doors, but do not operate electrical switches, extractor fans or doorbells on the way.
- Leave the property and call the National Gas Emergency Service on 0800 111 999 from outside.
Only return to evidence collection once the emergency service has made the situation safe and told you it is safe to do so.
Watch out: never dismantle, move or ‘test’ a gas appliance to get a better photo. You can create the leak you are trying to document, and you can compromise the evidence an inspector would rely on.
What makes a report actionable
An investigator needs to answer four questions from your submission: who did the work, what did they do, when and where, and why is it unsafe. Evidence that answers all four is worth more than a folder of unrelated photos.
- Identity. The engineer’s name, trading name, and any Gas Safe ID number shown. If no card was shown, say so, that is itself relevant.
- The work. Photos of the appliance, flue, pipework and any warning signs, taken from a safe distance. Include wider shots showing where the appliance sits in the room, not just close-ups.
- The paper trail. Invoices, quotes, receipts, text messages and any written record of the job. These establish that work was carried out for payment, which matters for the criminal route.
- The timeline. The date and address of the work, and the date you first noticed the problem.
- The risk. Notes on symptoms (headaches, dizziness, nausea that ease when you leave), any carbon monoxide alarm activation, and any sooty or yellow flame you observed.
Store everything in one place, a folder on your phone plus a paper copy, and label each item with the date it was taken.
Writing the complaint letter
Keep it short, factual and front-loaded with the risk. A structure that works:
Dear Gas Safe Register,
I am writing to report a concern about gas work carried out at [address] on [date] by [engineer name, company name, Gas Safe ID number if known].
The concern is [describe what you saw, in plain facts]. I am worried about [the risk, such as carbon monoxide or an unsafe flue].
I have attached [photos, invoices, notes]. Please let me know if you need anything else.
Yours faithfully,
[Your name, address, phone number and email]
Send it through the Register’s reporting channel and keep proof of sending. If you report online, save the confirmation screen or email.
What not to include
Leave out speculation about the engineer’s motives, character or prices. Investigators act on observable facts and documents, so a short letter that states the risk and attaches the evidence is most useful.
Booking a Verified Gas Engineer for Your Next Job
Once a concern has been raised, or if your current gas work needs replacing, choose your next engineer with care. Check the Gas Safe ID card, confirm the engineer’s registration number on the register and ask what work is covered in writing.
Major Heat provides Gas Safe registered boiler servicing, repairs and installation across Kent. If you need a trusted engineer, you can book boiler servicing with Major Heat and get the work checked by a registered professional.
Before you book anyone, ask for a written quote and confirm the engineer will issue a Gas Safe record of the job.
Frequently Asked Questions
How do I report an unsafe gas engineer?
You can report an unsafe or illegal gas engineer to the Gas Safe Register, which regulates gas engineers working in Great Britain. Start by gathering the engineer’s name, the date and address of the work, and any Gas Safe ID card details you were shown. Submit your concern through the Register’s online reporting form. If there is an immediate danger, such as a suspected gas leak, contact the National Gas Emergency Service on 0800 111 999 first.
Can I report a Gas Safe registered engineer?
Yes. Being Gas Safe registered does not prevent a complaint. If a registered engineer has carried out work that you believe is unsafe or non-compliant, you can raise a concern with the Gas Safe Register. Note the engineer’s registration number and the category of work they are registered for, then describe what you observed. The Register will investigate and may take action if the work breaches the rules.
What information do I need to report a gas engineer?
Have the engineer’s full name, their Gas Safe registration number if shown, the company name, the property address and the date of the work to hand. Describe the appliance involved, what was done and what concerned you, such as a missing safety device or an unflued heater. Photographs of the appliance, any paperwork such as a CP12 landlord gas safety record, and the invoice all strengthen your report.
What should I do if I smell gas after an engineer has worked on my boiler?
Leave the property immediately, do not use switches, naked flames or electrical devices, and open windows and doors on your way out if it is safe to do so. Once you are outside, call the National Gas Emergency Service on 0800 111 999. Do not return until the emergency engineer confirms it is safe. After the incident is resolved, you can still report the original engineer to the Gas Safe Register.
