Is it legal (UK law) to replace the fan on a domestic gas boiler yourself?

The replacement (according to the manual) involves three screws and two blade connectors. The price of a new fan from the manufacturer is quite reasonable, the price quoted for fitting it is six times the cost of the fan!

My research so far indicates that I can do my own 'wet work' on the water pipes, radiators and pump etc. Plus I'm pretty sure I can work on the room thermostat and the external controller myself.

The regulations make it clear that I can't work on 'gas carrying components' - which I guess means the gas pipes, gas valves and burner etc.

I haven't been able to find any authoritative reference to other non-gas components in the boiler. Some sources suggest that you can't even remove the cover of your own boiler, others suggest that it's fine to remove the cover and replace switches, controllers, knobs and fans etc etc.

Anyone here able to offer any definitive advice (preferable with link to an authoritative source)

(For what it's worth, I'm a professional engineer, and probably qualify as a 'competent person')

UPDATE - the question is about which parts of a boiler can/can't be self-maintained. I know wet-work is ok, I know gas-work is not ok. What about electrical work?

2 Answers 2


My understanding (I’m not legally qualified nor a Gas Safe registered person, so I am not offering an interpretation of them or advice here) of the UK gas regulations is that to work on gas appliances you need to be “competent” and to do paid work (or arguably work for others) you must be Gas Safe registered. Being Gas Safe registered clearly demonstrates competence.

There appears to be a grey area that is open to debate whether or not the above allows you to work on your own appliances at home.

Are you competent? If you do the work safely and leave it correctly functioning with no leaks, you may be. If your house subsequently blows up or a family member dies from carbon monoxide poisoning, you probably weren’t and may be in a world of trouble.

Further, my understanding of the position with relation to replacing the fan (I’m assuming here that the fan is in the intake / flue in your boiler - it generally is) is that the intake / flue assembly is considered part of the “gas side” of the boiler, presumably due to the need for the boiler to be “room sealed” to prevent the possibility of a carbon monoxide leak into the house. To access the flue to replace the fan, you therefore need to be competent to do so.

In summary:

Can you legally work on boiler electrics yourself? Possibly, but maybe not the fan.

Should you work on them? I’d suggest not. The risk could be considered significant.


You can work on the boiler if you are Gas Safe (oka Corgi) registered.

Sadly, even as a professional engineer who may well understand gasses, reactions etc much better than a registered installer, you don't qualify as a competent person...

Some registered people may be prepared to allow you to do bits and sign off on them after they have inspected - but they are about as rare as hen's teeth... (and yes my neighbour was registered and did that for me...)

  • Waiting for the ———- downvoter to either explain why I am wrong or provide a better answer... pigs may learn to fly first though.
    – Solar Mike
    Aug 7, 2020 at 19:26
  • there's no such thing as 'corgi' anymore. For over 10 years it's been 'gas safe' Aug 7, 2020 at 20:09
  • Same difference - I had one prepared to let me do the maintenance on my boiler and soldering on copper pipes for gas - even pushed a copper pipe through a curve under 6” of concrete which he could not believe and he still signed off on it. But if you don’t have one then you have to pay them.
    – Solar Mike
    Aug 7, 2020 at 20:32

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