Fitting of external oil boiler correctly

[Best]

If the pipes are lagged through the wall with Armaflex insulation, whether sleeved or not, it will probably be fine, especially if a dry wall.
But, to throw a spanner in the works, - mice can easily get into the house by simply chewing through the Armalex!
Actually better to leave the last bit of pipe bare & just use insulation tape on it & then weak sand & cement to fill the gap, so to stop mice!

 

[Bunker]

and if plastic pipe has been used there's no protection from damage

Plastic shouldnt be used within 1 metre of the boiler iirc.