yes I did some of the diy myself - a few rads etc etc.
Then the pros came in and did the real install inc. the boiler. When it was all done (and working fine) I found:-
Inside the boiler gubbins was much brick dust and plaster chunks from the holes in the ceiling above. I notice the boiler has a small linear actuator inside but fortunately it is facing donwards so no brick dust got to its grease lubricated shaft. I cleaned up as much as I could - that brick dust is sheer hell when it gets on something. Am sure you folk here already know that - I've seen it ruin screw threads and cause binding etc But really, so unprofessional I thought. Especially when the thing came in a substantial plastic cover that could have been used to cover the top.
Under the carpets I found a plentiful supply of sawdust and wood chips.
Am too ****** off to write more - oh, I will mention that they charged for Sentinel X100 (£30) but actually used "Trade inhibitor".