Christian McArdle wrote:
Would I be better off sticking in the Y-piece to connect cold water
to both inlets?

There's probably little in it. If you've got it working one way,
stick with it.

Also, it will only draw hot on 60C+ washes. If you only do 40C
washes, then it is academic.

Our machine draws hot and cold on all washes, but only hot on 60 or
above.