A lot of the information is all there already.
His system was installed incorretly by a HETAS registered installer and is incapable of correcting his errors.
This is where the term "qualified" becomes a joke.
I don't recall him being Hetas registered, but yes it is a joke. You can have as many letters after your name as you like, it don't make you practical in the field, in fact I would go as far as saying completely the opposite as they can't think outside the box.
And whilst I'm going on, a flapper valve will not stop gravity circulation going the right way, provided it has a long straight vertical run.
Instead of fluffing about with 3d images a simple line drawing with all the information would have been 10 x better.