Hi, bad news is….
It is a criminal offence to work or allow work on any domestic gas appliance or gas fitting.
Also your builder could not have filled in any of the paperwork for the boiler, therefore the boiler would not have been registered with manufacturers.
They will not come out to repair the boiler if it was to develop a fault.
A gas engineer would normally register the installation with corgi who would in turn send you a certificate which you would need if you ever came to sell the house.
If you had a leak, or worse still, a fire or explosion your insurance is unlikely to pay for any damage to you or any third party.
Also you builders insurance wouldn’t pay out either because he’s doing work he’s not qualified to do.
I would get a gas engineer to do a gas safety check on the whole installation, not just the boiler.
A gas engineer can’t register anybody else’s work as there own, in fact he/she is under obligation to report a dangerous or potentially dangerous installation (RIDDOR)
Also the engineer will disconnect any dangerous installation.
If you decide not to do anything about it and in the future the boiler develops a fault, the gas engineer you call out to repair the boiler will also disconnect the boiler from the gas supply if he/she thinks it’s dangerous .
Ignorance is no defence, if your builder is ‘caught’ he will be prosecuted, and there is a chance you would too.
First thing to do is to give Corgi a call (anonymously if you want) and explain the situation, it’s in their interest to give you the best advice.
Then get somebody out to check the installation, for peace of mind.
Sorry it all sounds OTT, but the gas industry is heavily regulated and engineers have to pay a lot of money to keep up to date and have regular inspections, you won’t get much sympathy off them.
Also like to say that a safety check, even if it passes, does not mean the boiler is then registered,it won't be of much help if you try to sell the house.