alt Hacker Newsi installed mine myself and probably illegaly. But its super easy and those people who install it do a shit job sometimes. I watched professionell people flushing those pipes with compressed air....
And the fine is nonexistent so everyone should do it themself.
I also don't think it's that hard, at least by looking at the YouTube videos.
Do you risk to lose house insurance in case of issues?
This is one of the reasons why sometimes I am even afraid of thinking about such DIY projects.