On a previous thread @Nickfromwales gave me this info:
If you tick the boxes, so.....
1) incoming mains into propery
2) stoptap of whatever guise
3) double check NRV
4) drain off cock
So first question is, can 2 and 3 be swapped around? and secondly is there any advantage to using a 28mm double check valve instead of a low loss 22mm DCV wrt flow rates.