DIY gas work... is it allowed?

This question crops up regularly, often going something like this...

I'd like to fit my own boiler but a Gas Safe Register (previously CORGI) bloke I know says it is illegal. Other people have told me it's fine for me to fit it myself as long as I get the gas connection done by a Gas Safe Register fitter. I want to stay within the law but don't want to end up paying someone else to do work that actually I'm legally entitled to do myself. As a DIY-er what can I do and what must I not do to stay within the law?

As with all things gas, there is no straightforward answer.

The answer lies (or should lie) in the law which governs the installation and use of gas fittings. The legislation you need to comply with is called the "Gas Safety (Installation and Use) Regulations 1998". Published on the HMSO website here. (I also have a copy of the regulations in one single large document here, which is easier for conducting text searches.) 

Once you've read through it I predict you will feel none the wiser ;-) Some of its content is ambiguous at best, self-contradictory at worst.

Getting to the point is difficult. You must either accept somebody's personal interpretation of the gas regs, or read and interpret them yourself. Here's my own interpretation (which the court may decide is wrong if it ever came to be tested, so DON'T rely on it):

The regulations draw a distinction between doing gas work for nothing and doing it in return for payment (of any kind - not just money). If you are receiving payment you MUST be Gas Safe Registered, or the penalty can be a prison sentence. If you are NOT being rewarded in any way (e.g. DIY for yourself) then you need only be what the regulation describes as 'competent'. 

For the potential DIYer the problem is deciding what the law means by 'competent'. This open to wide interpretation. You are certainly competent if you go to technical college and pass the exams accepted by Gas Safe Register for membership. At the other end of the spectrum a CORGI (no longer the gas register administrator - except in Northern Ireland) inspector once suggested to me that if you fitted your own boiler and followed the instructions fully and accurately in every way and there were no 'gas incidents', that could constitute proof of 'competence' too.

However, successfully following the boiler installation instructions accurately does not address all the legal requirements in the gas regulations in my opinion. Boiler instructions never give details on things like how to install the gas service pipe, how to calculate the size it needs to be, or how to test it for leaks after installation, for example.

It's my view that you comply with the law if you install the boiler yourself but get a person with formal proof of competence to install and connect the gas service and flue components. Getting them to commission the boiler is more or less essential too because the DIYer is most unlikely to have the tools and knowledge to correctly carry out the four compulsory safety checks defined in the gas regulations.

So there you have it. My view is that it's OK to fit your own gas appliance provided you get the gas pipe and flue installed and the safety checks carried out by a qualified person, but my view doesn't count. If something goes wrong it will be the view of the court that counts. The court will decide what the gas regulations mean, not me or anyone else ready to hand out free legal advice, qualified or not. 

If you are thinking of DIY, I advise you to read the gas regulations, and then it's your call...