So to today's questions on our ASHP install.

[Nickfromwales]

1 hour ago, SimonD said:

 

Pls see @MikeSharp01 comment below which clearly says it better than I ever could. Thankfully he woke up this morning with a clear head, unlike you and me that get into discussions late at night when we should probably be getting some sleep, or at least I know I should've been! 😁

 

 

He uses his words well lol. 

[Nickfromwales]

5 hours ago, MikeSharp01 said:

Yes that makes sense. So "b. be a separate branch pipe with no sanitary appliances connected to it;" means (not implies) the D2 pipe is a branch pipe itself? Hope that helps @Nickfromwales  

I only ever do a pair of D1 max into one D2 and that goes to one trap on one branch off the stack where practicable. 
 

Theres no problem if its a 40mm pipe coming off that picks up more than one trap, and the other traps collect water from appliances.

 

See here where D2 is on a 40mm run that picks up both discharges from the softener that sits in that chair. 
 

 

Nowt wrong with this setup.