No, stick with what you've got, a knuckle at the base of the stack isn't the best idea. Check your distances on that shower connection, although it does look like its well above 450mm from the bottom of the stack.
Yes, ideally you need a chamber somewhere on that corner. Appreciate the gas pipe is in the way, but what I'd do is put a 45° bend initially, then the chamber, then another 45 to turn the rest. Ultimately its up to you, I can only advise how I'd do it, based on my experience. Appreciate you didn't put a lot of this in yourself, but whoever planned it/thought it was acceptable really should stick to what they're good at. (It isn't drainage....)
Yes, ideally you need a chamber somewhere on that corner. Appreciate the gas pipe is in the way, but what I'd do is put a 45° bend initially, then the chamber, then another 45 to turn the rest. Ultimately its up to you, I can only advise how I'd do it, based on my experience. Appreciate you didn't put a lot of this in yourself, but whoever planned it/thought it was acceptable really should stick to what they're good at. (It isn't drainage....)
