I worked on one in Derbyshire which was aired a couple of months ago tbh the cast and crew are all ok I thought they would be a little bit "luvvie" but weren't at all the finish standard is pretty good considering the timescale I've also been back since the build and everything seems to be still...
is house built by wilcon by any chance?
if so almost certainly blocked on 10mm branch of tee from 22mm flow/return
they had a habit of using non barrier pipe for heating around my area with similar system set-up and can be a nightmare to sort out
chemicals/powerflushing tends to be waste of...