I applaud you for trying to help your colleague but there are many other considerations to take into account when deciding if this installation is safe. Since the installation cowboys have made such fundamental errors you can't have any confidence in their abilities to correct the faults.
The boiler manufacturers instructions only tell you half the story...there's a raft of other regulations to comply with.
Since Lee will not do the sensible thing and have the lot inspected I advise you to give up....he's a lost cause, otherwise it will all come back to you...end of friendship.
You learn in this game that some people are a waste of space....and no amount of persuasion will convince them...so bale out now.
I hear what your saying... I think the problem with lee is he just don't understand.
when I initially told him about the problem and the danger his reponce was the waters still hot...
I feel I cant leave it, I know these guys have actually fitted the same system next door... chances are they have done the same thing.
the building used to be a single guest house 2 into 1, its now been split up again, the the heating and electric always remained separate and never crossed.
Before the building were split the boilers were installed... one was replaced then just weeks later the boiler in the other building broke down and it was decided to just "upgrade"
without going into detail this was due to marriage breakup (splitting building back up)... so not exactly on speaking terms to warn of the possible danger just lerking next door. (she wont even answer door to us!)