Peccavi,
Its people like you that will end up killing someone its not just a question of replacing a fan! its what checks you have to do after that fan has been replaced!
Never DIY with gas
Last year, 14 people died from CO poisoning related to gas and, 234 people suffered serious health problems. Be gas safe in your home and never DIY with gas, even if you think it might save you money.
If someone other than a Gas Safe registered engineer does the gas work in your home, you could be risking the safety of your family and your property.
If gas appliances are incorrectly fitted, badly repaired, or poorly maintained, they can produce carbon monoxide which can kill.
Make sure that you always use a Gas Safe registered engineer to carry out gas work and service appliances in your home.
And why don't you get your information from a reliable source rather than wikipedia this information is from the gas safe registers website
If they are not Gas Safe registered (they have to register even if they have gas qualifications) and can’t show you their ID card, they are illegal.
If they put in a gas fire for example, but they’re only Gas Safe registered for pipework and boilers, they are illegal.
If they work for a Gas Safe registered firm during the week and are doing private work in their spare time on the side, they are illegal.
Gasman, December 2009