We're planning to replace an old CH boiler with a combi boiler and it's been pointed out that the gas feed to the existing boiler isn't
22mm as required for the combi.
The gas meter is at a front corner of the house and the new boiler will be at a back corner on the same side. So to minimise the disruption to decor we're proposing to take the feed along the outside of the side wall. The side wall of the house is right on the property boundary and faces on to a shared yard area in the adjacent property so there should be no problem with access to do the work
Would running a gas pipe along the wall be acceptable per whatever regs apply?
What type of pipe and what (if any) protection for it would be required (or advisable)?
Any gotchas to worry about?
[Of course, the CH engineer we choose should be able to tell me the answers, but I'd value independent expert opinions in advance]